Preface

QCVN 18: 2014/BXD is compiled by the Institute of Construction Science and Technology, submitted by the Department of Science, Technology and Environment, appraised by the Ministry of Science and Technology, and promulgated by the Ministry of Construction in accordance with Circular No. 14/2014/TT-BXD dated September 5, 2014 by the Minister of Construction.

1 GENERAL PROVISIONS

1.1 Scope

This code specifies technical safety requirements in the construction of civil, industrial and urban infrastructure works (hereinafter referred to as construction works).

Requirements for safety equipment for workers and safety inspection of on-site machinery shall comply with current regulations of the Ministry of Labor, Invalids and Social Affairs.

1.2 Subjects of application

This code applies to organizations and individuals involved in construction activities.

1.3 Referenced documents

The following referenced documents are indispensable for the application of this code. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

QCVN 01: 2008/BCT, National technical regulation on electrical safety;

QCVN 02: 2008/BCT, National technical regulation on safety in storage, transportation, use and disposal of industrial explosives;

QCVN QTĐ-5: 2009/BCT, National technical regulation on electrical engineering, Part 5 – Inspection of electrical system equipment;

QCVN QTĐ-06: 2009/BCT, National technical regulation on electrical engineering, Part 6 – Operation and repair of electrical system equipment;

QCVN QTĐ-07: 2009/BCT, National technical regulation on electrical engineering, Part 7 – Construction of electrical works;

QCVN 02: 2011/BLĐTBXH, National technical regulation on occupational safety for electric elevators;

QCVN 03: 2011/BLĐTBXH National technical regulation on occupational safety for electric welding machines and electric welding work;

QCVN 07: 2012/BLĐTBXH National technical regulation on occupational safety for lifting equipment.

1.4 Terms and definitions

The following terms are used in this Code:

1.4.1 Competent authority: a state agency with construction authority to promulgate regulations on construction activities; inspect and examine construction in accordance with the law.

1.4.2 Worker: a person currently working at a construction site or production facility of the Construction sector.

1.4.3 Construction machinery: mechanical transport vehicles and equipment serving construction and installation at construction works.

2 TECHNICAL PROVISIONS

2.1 General requirements

2.1.1 Construction is not permitted when there are insufficient technical and organizational documents on construction measures, which must specify technical measures to ensure occupational safety and fire and explosion prevention.

2.1.2 Workers working at height and in deep tunnels must have tool bags. It is not allowed to drop or throw materials, tools, and equipment from above.

2.1.3 Only workers who are trained and meet swimming requirements are allowed to work on rivers and water; they must be fully equipped with boats, life jackets and other necessary first aid equipment in accordance with regulations. For divers, they must fully comply with regulations on working conditions, allowances and health protection. All boats, life jackets and other first aid equipment must be inspected to ensure quality before use.

2.1.4 Workers on construction sites must use proper and sufficient personal protective equipment as prescribed.

NOTE: Some specific examples: Regarding requirements for electric welders, according to 3.4.2 of QCVN 3: 2011/BLĐTBXH; Regarding requirements for safe management and use of lifting equipment, according to 3.6 of QCVN 7: 2012/BLĐTBXH…

2.1.5 When working at height (from 2 m or more) or not yet reaching that height, but there are dangerous obstacles below the workplace, workers must be equipped with safety belts or protective nets. If it is not possible to make a safe working platform with handrails, workers are not allowed to work without wearing safety belts.

2.1.6 It is not allowed to construct simultaneously on two or more floors on a vertical line, if there is no safety protection equipment for workers below.

2.1.7 It is not allowed to work on scaffolding, chimneys, water towers, power poles, pillars or bridge beams, roofs of two or more stories during heavy rain, thunder, storms or winds of level 5 or higher.

2.1.8 After each period of heavy rain, strong winds or after many days of construction suspension, safety conditions must be rechecked before continuing construction.

2.1.9 There must be sufficient ventilation measures and means to prevent toxic gases or collapse when working in deep wells, underground tunnels or sealed tanks. Before and during work, there must be a strict inspection regime and a person on duty outside to ensure regular communication between inside and outside and timely first aid in case of accidents.

2.1.10 At the construction site, a system of sufficient lighting must be arranged on traffic routes and areas under construction at night. Working in unlit places is not allowed. Lighting at the workplace is from 100 to 300 lux, general lighting is from 30 to 80 lux.

2.1.11 There must be a lightning protection system to protect the entire construction site during construction.

2.1.12 When there is a risk of radiation exposure at the construction site or at construction sites containing natural radiation sources, it is necessary to comply with the current state regulations on radiation safety and control.

2.1.13 The construction site must have an occupational safety log book and fully record the situation of incidents, accidents, remedial and handling measures during construction.

2.1.14 At the construction site, all work positions must be kept neat and tidy. Equipment and tools must always be placed in the designated place. Waste and excess materials must be cleaned up regularly.

2.2 Organization of construction site

2.2.1 General requirements

2.2.1.1 The surrounding area of the construction site must be fenced off and guard stations must be arranged to prevent unauthorized persons from entering the site. In case there is a public traffic road passing through the site, another road must be opened or there must be signs at both ends of the road section passing through the site for vehicles to reduce speed.

2.2.1.2 On the construction site and construction areas, there must be a drainage system to ensure that the construction ground is dry and clean. Water must not be allowed to stagnate on the road surface or flow into the foundation pit of the works. Construction sites near the sea, rivers, or streams must have plans to prevent floods and landslides.

2.2.1.3 Auxiliary works generating toxic factors must be located downwind, ensuring a safe distance to the living quarters of cadres and workers on the construction site and local residents or have measures to prevent toxicity in accordance with current state regulations.

2.2.1.4 Wells, tunnels, pits on the ground and holes on the building floors must be securely covered to ensure the safety of passers-by or surrounded by solid fences with a minimum height of 1 m. For trenches and foundation pits located near traffic roads, there must be fences over 1 m high, and at night there must be warning lights.

2.2.1.5 There must be solutions to transfer excess materials and waste from high places (over 3 m). It is not allowed to dump excess materials and waste from above when the area below has not been fenced off, no warning signs have been placed and there are no lookouts.

2.2.1.6 There must be measures to ensure the safety of people and objects (such as fences, warning signs, or canopies, etc.) in dangerous areas where objects may fall freely from above. The limits of this dangerous area are determined according to Table 1.

Table 1 – Limits of dangerous areas for construction works

2.2.1.7 Areas where formwork and scaffolding are being dismantled, old structures are being demolished; where structural components of the works are assembled, where large machinery and equipment are assembled; areas with toxic gases; intersections of traffic roads must have fences or signs, and at night there must be warning lights.

2.2.2 Walkways and transportation routes

2.2.2.1 At traffic hubs on the construction site, there must be clear diagrams indicating each route for mechanical and manual transport vehicles. On the routes of the construction site, a traffic sign system must be installed in accordance with current traffic safety regulations.

2.2.2.2 When using manual or mechanical means to transport across ditches, planks, bridges, or culverts must be arranged to ensure safety for people and vehicles. The dimensions and structure of planks, bridges, and culverts are determined according to current standards.

2.2.2.3 The minimum width of a one-way road is 3.5 m and 6 m for a two-way road. The minimum turning radius is 10 m.

2.2.2.4 Traffic roads for motor vehicles, intersections with railways, the regime of placing warning signs and guard stations must comply with the regulations of the Ministry of Transport.

2.2.2.5 When it is necessary to arrange transportation routes passing under positions or structures with construction parts above or machinery and equipment operating above, protective floors must be made below.

2.2.2.6 Roads or bridges for workers to transport materials to high places must not be steeper than 30° and must be stepped. At high and dangerous positions, there must be protective handrails to ensure safety.

2.2.2.7 The entrances to buildings or works under construction on upper floors must be closed corridors and have cross-sectional dimensions suitable for the density of people, equipment and construction tools when moving through the corridors.

2.2.2.8 Rubber-insulated electrical wires passing through transportation roads must be suspended high or put into protective pipes buried at least 40 cm deep below the ground. Water pipes must be buried at least 30 cm deep below the ground.

2.2.3 Arrangement of materials, fuels, components and equipment

2.2.3.1 Storage yards for arranging and preserving materials, components, and equipment must be pre-determined on the construction site with sufficient quantities to serve construction. The locations of these areas must be convenient for transportation, loading/unloading and preservation. Materials must not be arranged on any unstable or unsecured parts of the structure.

2.2.3.2 In storage yards containing materials, fuels, components, and equipment, there must be transportation routes. The width of the routes must be suitable for the dimensions of the transport vehicles and loading/unloading equipment. Between material stacks, walkways for people must be at least 1 m wide.

2.2.3.3 Materials, fuels, components, and equipment must be placed at least 2 m away from motor vehicle roads, railways, and crane roads, measured from the nearest road edge to the outermost edge of the material (on the road side).

2.2.3.4 When loose materials (sand, crushed stone, gravel, slag, etc.) are dumped into yards, there must be technical measures to prevent sliding to ensure safety for people and equipment.

2.2.3.5 Powdered materials (cement, gypsum, lime powder…) must be packaged in bags or contained in sealed containers, silos, bunkers…, and there must be measures to prevent dust during loading/unloading.

Large containers for powdered materials must have lids or protective nets. The inside of the container must be fully illuminated. Workers are only allowed to enter silos, bunkers, and storage when guided and supervised by a construction technical officer. There must be specialized equipment to ensure worker safety (winches, safety belts…).

2.2.3.6 Liquid and flammable materials (gasoline, oil, grease…) must be stored in separate warehouses in accordance with current fire prevention and fighting regulations.

2.2.3.7 Acids must be contained in sealed porcelain or acid-resistant glass bottles and must be placed in separate well-ventilated rooms. Acid containers must not be stacked on top of each other. Each bottle must have a label clearly stating the type of acid and date of manufacture.

2.2.3.8 Toxic substances, explosives, and pressurized equipment must be stored, transported and used in accordance with current state regulations on chemical safety, explosives and pressure equipment.

2.2.3.9 When arranging materials on the banks of trenches and deep pits, calculations must be made to ensure construction safety as prescribed in 2.12.

2.2.3.10 Rubble, paving bricks, and tiles must be stacked in compartments not exceeding 1 m in height. Flat-stacked bricks must not exceed 25 courses high.

2.2.3.11 Floor slabs and roof slabs stacked must not exceed 2.5 m in height (including the thickness of the cushioning layers). Wall panels must be placed between support frames to stand upright or on A-frame racks. Partition panels are only allowed in an upright position in rack frames.

2.2.3.12 Foundation blocks, tunnel wall blocks, sanitary and ventilation blocks and slabs, garbage chute blocks stacked must not exceed 2.5 m in height (including the thickness of the cushioning layers).

2.2.3.13 Long prefabricated components stacked must not exceed 2 m in height (including cushioning layers).

2.2.3.14 Component blocks and slabs stacked must not exceed 2.5 m in height (including cushioning layers).

2.2.3.15 Insulation materials stacked must not exceed 1.2 m and must be stored in a sealed, dry warehouse.

2.2.3.16 Steel pipes with a diameter of less than 300 mm must be stacked in layers and not exceed 2.5 m. Steel pipes with a diameter of 300 mm or more, cast iron pipes stacked in layers, must not exceed 1.2 m and must have firm bracing measures.

2.2.3.17 Steel plates and sections stacked must not exceed 1.5 m in height. Small sizes are stacked on racks with similar heights; the load of steel stacked on racks must be less than or equal to the allowable load of the supporting rack.

2.2.3.18 Timber logs stacked, with underlayment, must have stakes on both sides and must not exceed 1.5 m in height. Sawn timber stacked must not exceed 1/2 the width of that stack; if stacked alternating between horizontal and vertical layers, it must not exceed the width of that stack, including the thickness of the cushioning layers.

2.2.3.19 Glass must be crated and placed in upright frames. Only one layer is stacked, not on top of each other.

2.2.3.20 Machinery and technical equipment of the works are only allowed to be stacked in one layer.

2.3 Installation and use of electricity in construction

2.3.1 When installing, using, repairing electrical equipment and construction power grids on the construction site, in addition to the provisions in this Code, it is also necessary to comply with the provisions in QCVN QTĐ-5: 2009/BCT, QCVN QTĐ-06: 2009/BCT, QCVN QTĐ-07: 2009/BCT, QCVN 01: 2008/BCT and other current regulations on electrical engineering and electrical safety.

2.3.2 Electricians as well as workers operating electrical equipment must be trained and certified to meet the requirements of electrical safety techniques. Electricians working in any area on the construction site must have a thorough grasp of the power supply diagram of that area. Electricians on duty at electrical equipment with voltages up to 1,000 V must have level 4 or higher electrical safety qualifications.

2.3.3 At the construction site, there must be a power grid diagram, with a general switch and sectional switches to be able to cut off the power to the entire or each area of the works when necessary. There must be two separate systems for power and lighting.

2.3.4 Exposed conductive parts of electrical equipment (wires, busbars, contacts of switches, fuses, terminals of electrical machines and equipment…) must be completely covered with insulating materials or placed at a safe height that is convenient for operation. The ends of exposed wires and cables must be insulated, covered, or suspended high. For conductive parts that are exposed according to design requirements or due to structural requirements, they must be suspended high, must have fences and warning signs.

2.3.5 Wires serving construction in each area of the works must be insulated wires; must be mounted on poles or firm supports; must be at least 2.5 m high for construction ground and 5.0 m high for areas with vehicle traffic. Electrical wires less than 2.5 m from the ground or working floor must use rubber insulated cables. Electrical cables used for mobile construction machinery must be wound on drums or slid on cable troughs. Electrical cables must not be allowed to rub on the ground or be run over by vehicles or pressed on by other structures.

2.3.6 Lighting fixtures with voltages greater than 36 V must be suspended at least 2.5 m from the working floor.

2.3.7 Electrical grids, distribution mechanisms, switchboards and their branches that are in the process of being installed must not be used to replace temporary electrical networks and equipment used on the construction site. Construction electrical wires and welding wires must not be allowed to come into contact with conductive parts of the structures of the works.

2.3.8 Electrical equipment, cables, electrical consumers… on the construction site (excluding in warehouses) must all be considered as voltage, regardless of whether they have been connected to the power grid or not.

2.3.9 Electrical switching devices used to switch the integrated common power grid and branch lines supplying power to each area of the works must be strictly managed so that unauthorized persons cannot automatically switch power. Switches supplying power to each device or group of devices must have secure locks. Electrical switching devices, switches… must be placed in sealed boxes, placed in dry, safe and convenient places for operation and troubleshooting. When cutting off power, it must be ensured that the switches or other power cutoff devices cannot self-close the circuit. In case of power loss, the switch must be cut off to prevent electric motors from starting unexpectedly when power is restored. Multiple electrical devices must not be simultaneously powered on by the same switching device.

2.3.10 Sockets used for mobile electrical equipment must be clearly marked with their maximum current. The construction of these sockets and plugs must have contacts so that the pole of the protective wire (ground or neutral) makes contact before the phase wire when closing and vice versa, while eliminating the possibility of mis-plugging the contacts. The electrical switch on mobile devices (except mobile lights) must be able to cut all phases and be mounted directly on the device’s housing. Switches must not be placed on mobile wires.

2.3.11 All electrical equipment must be protected against short circuits and overloads. Protective devices (fuses, relays, circuit breakers…) must be compatible with the voltage and current of the equipment or group of electrical equipment they protect.

2.3.12 All metal parts of electrical equipment, electrical switching devices, protective devices that may be energized when the insulating part is damaged and that a person may touch must be grounded or neutralized in accordance with current regulations on grounding and neutralizing electrical equipment. If an independent backup power source is used to supply power to the electrical equipment when the common power grid fails, the neutral mode of the backup source and the protective measures must be compatible with the neutral mode and protective measures when using the common power grid.

2.3.13 When moving large objects under power lines, there must be measures to ensure safety. Power must be cut off if the moving object has the ability to touch the power line or if electricity from the power line may arc through the moving object to the ground.

2.3.14 Only assigned electrical workers are allowed to repair, connect or disconnect electrical equipment from the power grid. Only after power has been cut off can the protective parts be removed, wires disconnected from the electrical equipment, and conductive parts repaired. It is not allowed to repair, remove, connect wires and perform work related to overhead power lines while power is on.

2.3.15 Switching power on and off to repair the main line and branch lines supplying power to 2 or more electrical devices must be notified to the person in charge of the equipment. These lines are only allowed to be re-energized after a thorough inspection and a written report from the person in charge of machine repair. After disconnecting the switch to repair individual electrical equipment, the switch must be locked and a sign prohibiting power on must be hung or a person must be on duty to avoid the situation of power being turned on while someone is repairing.

2.3.16 Fuse wires in fuse holders are only allowed to be replaced when power has been cut off. In cases where power cannot be cut off, this work is only allowed with tube or cap type fuses, but a load must be installed. When replacing tube fuses while energized, protective glasses, rubber gloves, insulated tools must be used and one must stand on a mat or wear insulated shoes. Blade type fuses must not be replaced while energized. When using a ladder to replace fuses at height while energized, there must be a person on duty below.

2.3.17 Light bulbs must not be removed and installed without cutting power. In case power cannot be cut off, the worker doing that work must wear insulating gloves and protective glasses.

2.3.18 Fixed lighting fixtures must not be used as handheld lights. In places with electrical hazards, lights with voltages not exceeding 36 V must be used. Handheld lighting fixtures must have a metal mesh protecting the light bulb, the wire must be rubber insulated, power taken through a socket. Sockets and plugs used for voltages not exceeding 36 V must have a structure and paint color that distinguishes them from sockets and plugs used for higher voltages. Workplace lighting fixtures must be placed at appropriate heights and angles to avoid glare from direct light from the bulbs.

2.3.19 The use of power sources to make protective fences for the construction site is not allowed.

2.3.20 Handheld electrical tools (power tools, mobile lights, safety step-down transformers, frequency converters…) must be inspected at least every 3 months for ground fault on the machine housing, the condition of the protective ground wire; must be inspected at least every month for the insulation of the wire, power source and exposed electrical parts. For mobile transformers, in addition to the above points, the short circuit of the high voltage winding and the low voltage winding must also be checked.

2.3.21 Autotransformers must not be used as a power source for lighting fixtures and handheld power tools with voltages not exceeding 36 V.

2.3.22 Electric motors, power tools, lighting fixtures and other devices are only allowed to be connected to the power grid using prescribed accessories. Electrical wires must not be twisted or spliced.

2.4 Loading, unloading and transportation

2.4.1 General requirements

2.4.1.1 When transporting materials and products for construction, in addition to the requirements of this section, the site regulations must also be complied with.

2.4.1.2 The maximum allowable load for each worker over 18 years old when loading, unloading, and carrying with a distance not exceeding 60 m is as follows: 50 kg for men, 30 kg for women.

2.4.1.3 Loading and unloading yards must be flat; routes for people and loading and unloading vehicles to move conveniently and safely must be specified.

2.4.1.4 Before loading, unloading and transporting, it is necessary to carefully consider the symbols, dimensions, weight and transport distance to determine and equip transport means to ensure safety for people and goods.

2.4.1.5 When transporting items with large dimensions and weights, specialized means must be used or a transport and unloading plan must be approved to ensure safety for people and equipment.

2.4.1.6 When transporting explosives, radioactive substances, toxic substances, pressurized equipment and flammable substances, transport means suitable to current state regulations must be used.

2.4.1.7 Loading and unloading at night or when there is insufficient natural light must be fully illuminated. When loading and unloading flammable and explosive materials, specialized explosion-proof lights must be used; open flame torches must not be used for lighting.

2.4.1.8 When loading and unloading round or rolled heavy materials (drums, cables, coils…), if taking advantage of inclined planes to roll or slide from top to bottom, ropes must be used to anchor from above, not allowing goods to roll down freely. Persons involved in loading and unloading are only allowed to stand above and on both sides of the inclined plane.

2.4.1.9 When transporting liquids contained in bottles, jars, specialized means must be used; wedging must be used to avoid spilling and breaking.

2.4.1.10 Ethylene gasoline must not be transported together with other goods.

2.4.1.11 Workers loading and unloading loose materials such as cement, lime, powder, gypsum, must be fully equipped with protective equipment according to current regulations.

2.4.1.12 Loading, unloading and transporting corrosive chemicals, toxic chemicals, compressed gas cylinders, and liquefied gas cylinders must be done carefully and gently, avoiding strong impacts and spills. Persons with oil and grease on them are not allowed to load, unload and move oxygen and compressed gas cylinders.

2.4.1.13 Using hoses to suck gasoline and oil by mouth or using tools to scoop gasoline and oil directly by hand is not allowed, specialized tools must be used. When scooping and pouring acid, it must be done slowly and carefully to avoid splashing acid on people, water must not be poured into acid but only acid poured into water when mixing. Workers performing this work must be fully equipped with personal protective equipment.

2.4.1.14 Loading goods onto railway wagons and truck beds must not exceed the load and size limits; must be firmly wedged and tied to avoid dropping, spilling, and shifting during transportation.

2.4.2 Transportation by rudimentary means

2.4.2.1 Before loading and unloading, it is necessary to: Check the means of transportation such as yokes, carrying poles and vehicle parts (shafts, wheels, vehicle beds, guard boards, tow ropes…) to ensure there are no broken ropes, broken shafts… during transportation; Check the transport route and the loading and unloading place to ensure safety for workers during work.

2.4.2.2 When carrying heavy objects requiring two or more people, one person must be assigned the responsibility to direct and give unified orders.

2.4.2.3 Before loading goods onto modified carts and tricycles, the wheels must be chocked and the shafts must be firmly supported.

2.4.2.4 When loading goods on vehicles:

• For loose goods: bricks, stones, sand, gravel… must be loaded 2 cm lower than the vehicle bed and have guard boards at both ends;
• For goods contained in soft bags such as cement, lime powder… can be stacked higher than the vehicle sides but not more than 2 bags and must be firmly tied;
• For bulky goods, they must not be stacked higher than 1.5 m from the road surface the vehicle is traveling on (for human-pulled or pushed carts) and must be firmly tied with ropes;
• For steel plates, angle steel, concrete components longer than the vehicle bed, they must be tied with steel wires.

2.4.2.5 Workers pushing tricycles and modified carts up slopes must walk on either side of the vehicle and must not lean on the goods to push. When parking on slopes, the wheels must be firmly chocked. When going down slopes greater than 15°, the vehicle shafts must be turned backwards and the puller must hold the vehicle to allow it to roll down slowly.

2.4.2.6 When using animal-drawn vehicles, the driver must walk on the left side of the animal, not next to the vehicle bed or sit on the vehicle bed. The vehicle must be equipped with a braking system, and have signal lights when transporting at night.

2.4.3 Transportation by car and tractor

2.4.3.1 When loading goods onto vehicles, depending on the type of goods, there must be measures to arrange them to ensure safety during transportation.

2.4.3.2 When taking materials from the discharge openings of bunkers, silos… the vehicle must be parked so that the center of the vehicle bed aligns with the center of the material flow from the discharge opening of the bunker, silo…

2.4.3.3 When transporting loose goods such as bricks, tiles, sand, gravel… they must be stacked or poured 10 cm lower than the vehicle sides. If stacking higher, the vehicle sides must be extended, the joints must be firm, but the load must not exceed the allowable load of the vehicle.

2.4.3.4 For light, bulky goods, they are allowed to be stacked higher than the vehicle sides but must not be wider than the allowable size of the vehicle, and must be firmly tied.

2.4.3.5 When transporting long, bulky goods such as: trusses, columns, floor slabs, wall panels, machinery and equipment… there must be chocks and firm ties. If the goods are longer than 1.5 times the length of the vehicle bed, a trailer must be attached, the trailer bed must be at the same height as the vehicle bed. The connection between the trailer and the vehicle must be ensured to be firm, to avoid breaking and free rotation when the vehicle moves. Dump trucks must not be used to transport goods longer than the vehicle bed or to attach trailers.

2.4.3.6 It is not allowed to transport people on cars, cranes, cargo vehicles, on dump truck beds, on trailers, semi-trailers, tankers and walled trucks (types not equipped to carry people). It is not allowed to carry people in vehicle beds containing toxic, explosive, flammable substances, compressed gas cylinders or bulky goods. It is not allowed to let people stand on the steps, the connection between the trailer, semi-trailer and the vehicle, on the hood, on the vehicle roof, or sit or stand in the empty space between the vehicle bed and the cabin.

2.4.3.7 Before driving off, the driver must:

• Check the entire braking system;
• Check the steering system, shift levers and linkages, brake nuts, safety pins;
• Check the lighting system, signal lights, horn;
• Check the connection parts between the trailer, semi-trailer and the tractor truck;
• Re-check the tie-down system on the vehicle.

2.4.3.8 For dump trucks, in addition to checking the parts as specified in 2.4.3.7, the following parts must also be checked:

• The locking pins preventing the dump bed from tilting;
• The ability to tightly clamp the dump bed and the lifting mechanism;
• The quality of the locking pins at the rear of the vehicle bed.

2.4.3.9 Within the construction site: Vehicles must not travel at speeds exceeding 10 km/h; when turning or rounding curves, they must travel at speeds not exceeding 5 km/h. The distance between vehicles traveling in the same direction must not be less than 20 m.

2.4.3.10 The driver must have a license corresponding to the type of vehicle being driven. Before leaving the vehicle, the driver must turn off the engine, engage the parking brake, remove the key and lock the cab door. When stopping the vehicle (engine still running), the driver must not leave the driving position to go elsewhere. Unauthorized persons are not allowed to enter the cab.

2.4.3.11 Vehicles must not park on slopes. In special cases where parking is necessary, the wheels must be firmly chocked.

2.4.3.12 The position of cars standing to dump materials into excavated pits is taken according to 2.6.1.15 and chocks must be placed to prevent the vehicle from backing up beyond the prescribed position. When vehicles park on overhead bridges to dump materials into foundation pits, the overhead bridges must be equipped with insurance barriers.

2.4.3.13 When turning around or reversing, the horn must be sounded and careful observation must be made to avoid people or vehicles passing by.

2.4.3.14 Tractors must not be used to pull loads up slopes exceeding 30° or down slopes exceeding 15°.

2.4.3.15 If using lifting equipment to load goods, when the goods have not been lowered, no one is allowed to stand in the vehicle bed, wagon bed or sit in the cab; workers must stand outside the vehicle bed or wagon bed to adjust the goods using hooks or ropes.

2.4.4 Transportation by train and mining cart

2.4.4.1 Railways and mining cart tracks must be constructed in compliance with current railway traffic regulations. The slope of railways and mining cart tracks used for hand-pushed wagons or carts must not exceed 2%.

2.4.4.2 The construction site must organize strict inspections of the routes, switches, and curve sections.

2.4.4.3 Overhead bridges on the routes must have protective handrails on both sides. The distance from the wagon side to the handrail must not be less than 1 m. The bridge surface must be covered with tight planks, on the plank surface on sloped sections there must be transverse wooden bars to prevent slipping for workers pushing carts back and forth.

2.4.4.4 The distance between hand-pushed mining carts traveling in the same direction on one route must not be less than 20 m for level roads; not less than 30 m for sloped sections. Mining carts must have good foot brakes and locking pins. Mining carts must not be braked by chocking the wheels or by any other means. Before putting carts into operation, the operator must check the braking devices.

2.4.4.5 For hand-pushed carts, there must always be an operator. It is not allowed to stand on the cart while it is moving or to let the cart run free.

2.4.4.6 When pulling carts up slopes using cables, there must be measures to prevent people from passing through the area at the foot of the slope and on both sides of the cable route.

2.4.4.7 The speed of pushing carts must not exceed 6 km/h. When approaching a siding or turntable, the speed must be reduced to allow the cart to slowly run. When carts are moving, a horn must be sounded to signal everyone to stay away from the cart tracks. If an incident occurs (cart tipping over, derailing…), a signal must be given for the carts behind to stop. When running carts at night or through tunnels, there must be adequate lighting.

2.4.4.8 Before loading or unloading goods onto or from carts, the brakes must be applied and the wheels chocked. Carts with tipping beds must have locking pins engaged. Goods loaded on carts must be firmly tied. If they are loose goods, they must be loaded 5 cm lower than the cart sides.

2.4.5 Transportation by waterway

2.4.5.1 Before loading and unloading goods onto or from ships, boats… they must be firmly anchored. Loading and unloading must be guided and supervised by the captain or a person authorized by the captain.

2.4.5.2 The gangway to and from ships and boats must not exceed a slope of 30° and must have transverse cleats. The width of the gangway surface must not be less than 0.3 m for one-way traffic; not less than 1 m for two-way traffic. One end of the gangway must have a hook to secure to the ship or boat, the other end must be firmly supported on the shore. When the gangway is longer than 3 m, it must have a mid-span support.

2.4.5.3 When transporting goods that are easily penetrated by water such as soil, sand, cement, lime… there must be tarpaulins or roofs to protect against rain.

2.4.5.4 Before loading and unloading goods, the loading and unloading tools, lifting and transferring equipment, and protective equipment must be inspected and repaired.

2.4.5.5 Goods must not be loaded onto ships and boats higher than the ship’s deck or the boat’s sides. Light, bulky goods can be loaded higher than the height of the boat, but must be firmly tied, and capsizing must be guarded against.

2.4.5.6 When there are winds of level 5 or higher, ships and boats must be brought to a safe shelter.

2.5 Use of hand tools and equipment

2.5.1 General requirements

2.5.1.1 Hand tools and equipment must be safe and convenient, moving parts must be maximally guarded, have a mechanism to immediately turn off and not accidentally turn back on, not operate beyond the safe speed marked on the tool and only start from the lowest speed.

2.5.1.2 Tools and equipment with a weight of 10 kg or more must be equipped with a mechanism for lifting and suspending when working.

2.5.1.3 Hand tools and equipment used for striking and chiseling must ensure:

• The tip is not cracked, chipped, or has any other damage;
• The handle is not cracked, broken, has no sharp edges and must have an appropriate length to ensure safe operation.

2.5.1.4 Tools and equipment provided to workers must be of the same set, accompanied by easy-to-understand and easy-to-implement instructions for use.

2.5.1.5 Power supply cables and compressed air hoses must be buried underground or suspended high, must not be pulled taut, twisted or folded during operation. Electric cables, welding power cables as well as steam pipes must not be placed on top of each other.

2.5.1.6 Only trained and designated persons are allowed to use electrical and compressed air equipment. When working, workers must use tools and tool parts according to their designed functions; must be in good health, alert and wear full necessary protective equipment (clothing, hat, glasses, mask, gloves, shoes, boots, safety belt…). When working at height, workers must be equipped with a container for small items; tools and the container for small items must be tied to avoid falling and causing accidents.

2.5.1.7 When not in use, hand tools and equipment must be turned off and packaged, stored neatly and carefully, avoiding breakage, avoiding injury from sharp parts. The sharp parts of tools and equipment must be covered when moving.

2.5.1.8 Before use, all safe working conditions of the tools must be checked, trial run without load to detect errors, parts that are or are about to be damaged need to be repaired immediately.

2.5.1.9 During work, workers must stand in a safe, stable position on 2 feet, use both hands to control the tool, and must not stand on extended ladder rungs. When drilling or tightening bolts, it must be ensured that the material being drilled or bolted has been firmly clamped. Absolutely do not use hands to clean metal chips, grasp rotating machine parts or place hands or feet near moving machine parts.

2.5.1.10 The power source must be immediately disconnected when abnormalities are noticed, when there is a power outage, loss of steam, when moving tools or when stopping work. Hand tools that are still being supplied with electricity or compressed air must not be left unattended.

2.5.1.11 Around areas with exposed electrical circuits, steel tape measures, aluminum rulers, metal-reinforced rulers with magnetic conductivity, screwdrivers and other conductive tools must not be used. Only insulated tools or those made from non-conductive materials are allowed to be used near places where electric current passes through and there is a risk of electric shock. Only tools that do not emit sparks are allowed to work near places with flammable and explosive dust and vapors.

2.5.1.12 During construction, there must be measures to prevent the possibility of puncturing structures, causing concrete, brick, stone and other material fragments to be ejected into surrounding people.

2.5.2 Mechanical hand tools

2.5.2.1 Wooden handles and bamboo handles of hand tools made from various types of bamboo and wood must be hard, flexible, not cracked, chipped, worm-eaten, rotten; must be smooth and firmly wedged.

2.5.2.2 Wrenches must be selected according to the correct size of the nut. The wrench jaws must not be skewed, the centerline of the wrench must be perpendicular to the longitudinal centerline of the nut. Nuts must not be tightened with wrenches larger than the nut by inserting a steel shim and holding the edge of the nut into the wrench jaws. Wrenches must not be extended with other wrenches or with steel pipe sections (except for specially assembled wrenches).

2.5.2.3 When chiseling metal or concrete with hand tools, workers must wear protective glasses. In narrow and crowded workplaces, there must be a protective screen.

2.5.3 Electric hand tools and equipment

2.5.3.1 Do not let water fall into sockets or plugs. Do not use electric hand tools and equipment in the rain.

2.5.3.2 Electrical tools and equipment must be grounded, except for double-insulated tools that have been tested and have a distinguishing mark.

2.5.3.3 When using electric hand tools and equipment in places with electrical hazards, voltages not exceeding 36 V must be used. In places with less electrical hazard, 110 V or 220 V voltages can be used, workers must wear boots or shoes and insulating gloves. When using electric hand tools and equipment inside metal tanks and wells, a person must be assigned to monitor from the outside.

2.5.4 Compressed air hand tools and equipment

2.5.4.1 The trigger of compressed air hand tools and equipment must be convenient for use and have a mechanism so that when there is no longer pressing force, the compressed air supply automatically cuts off.

2.5.4.2 Compressed air hoses must not be connected directly to the main pipelines but only through valves in the compressed air distribution box, or branch pipes.

2.5.4.3 Before connecting compressed air hoses, the hose must be checked for clearance. The branch hose is only allowed to be connected to or disconnected from the main hose when the compressed air supply has been stopped. Compressed air is only supplied after the tools and equipment have been placed in the predetermined position.

2.5.4.4 All compressed air hose connections must be tightened with iron bands. Compressed air hoses must not be tied or suspended with steel wire.

2.6 Use of construction machinery

2.6.1 General requirements

2.6.1.1 All construction machinery must have complete technical documents, which must include basic technical specifications, instructions for installation, transportation, storage, use and repair, have a shift handover book, a technical condition monitoring book.

2.6.1.2 Lifting equipment used in construction must have valid operating permits and lifting equipment inspection certificates. The equipment must be managed and used in accordance with QCVN 02: 2011/BLĐTBXH, QCVN 07: 2012/BLĐTBXH, current standards on lifting equipment and the provisions in this section.

For tower cranes:

• A construction method design must be established, clearly specifying the installation location, operating procedures, dismantling measures and measures to ensure occupational safety on the construction site;
• Proactive measures to prevent falling objects must be applied;
• When the operating range of the crane extends beyond the construction site, there must be measures to protect the safety of people and vehicles underneath in accordance with the provisions in Table 1;
• The tower crane must stop operating when wind speeds are level 5 or higher or according to the manufacturer’s regulations.

2.6.1.3 Lifting equipment must be clearly marked with the load capacity corresponding to each lifting radius and working conditions at each load level so that the operator can always see and strictly comply. Lifting equipment must have a firm base, the ground where the lifting equipment operates must be geologically surveyed and reinforced beforehand to ensure safe load-bearing. Before lifting, the weight of the goods must be known, the hooks and load cables must be checked, and the load balance must be checked at a height of 20 cm before lifting. A person must always be assigned to signal and monitor the lifting condition. Workers standing on the ground must not approach the lifting position and must wear protective helmets. Before lowering the load into trenches, pits, wells… the unloaded hook must be lowered to the lowest position, if the number of cable turns remaining on the drum is greater than 1.5 r, then the load may be lifted and lowered. Cable hooking and tying must be assigned to trained and experienced persons, not to women and children. The lifting and moving process must be commanded by an experienced person and must comply with unified signals.

2.6.1.4 Lifting equipment must not be used to lift people (except in emergency situations) and to drag loads; Loads must not be lifted over people’s heads, when loads must be lifted near crowded areas, there must be measures to shield the lifting area, if not possible, the route must be temporarily blocked or the direction of people’s travel must be changed during the lifting time; the distance between the crane jib or the lifted object to other stationary objects must be kept at a minimum of 50 cm.

2.6.1.5 Machinery that is pressurized equipment or has pressurized equipment must comply with the provisions in current standards on pressure vessels and the provisions in this section.

2.6.1.6 Construction machinery with electric motors must be: Insulated or covered for exposed live parts; Protective grounding for non-live metal parts of the machinery.

2.6.1.7 For fuel-powered machinery, smoking or bringing open flames near the fuel tank is strictly prohibited, and the fuel tank cap must not be opened by using metal objects to strike it. If a fire occurs and there is no fire extinguisher, the fire must be extinguished with soil, sand or covered with a tarp or felt, water must never be poured onto burning fuel.

2.6.1.8 Moving parts of machinery and areas where liquids or solids may be ejected when the machinery is operating and may endanger workers must be shielded or equipped with protective devices. In cases where shielding or equipping with other protective devices is not possible, signaling devices must be equipped. Particularly for cable drums, they must be left exposed to monitor the cable winding process and cable condition.

2.6.1.9 The operating mechanism of the machinery must ensure that when the machinery is in an abnormal working mode, there must be a warning signal, and in necessary cases, there must be a device to stop and automatically turn off the machinery.

2.6.1.10 Construction machinery must be equipped with audio and light signaling devices, must emit a signal before moving, when traveling on the road must comply with current traffic laws and the working parts must be retracted to a safe position. When operating on the construction site, there must be signs.

2.6.1.11 The control mechanism must eliminate the possibility of automatically or accidentally opening or closing the machinery.

2.6.1.12 Machinery must be installed according to the manufacturer’s instructions and must comply with the provisions in current standards on machinery safety.

2.6.1.13 The installation location of machinery must ensure safety for the equipment and workers throughout the use process. The ground where construction equipment moves and operates must have sufficient load-bearing capacity for the equipment and other loads throughout the construction process. If the ground does not have sufficient load-bearing capacity, ground reinforcement measures must be applied to ensure safety for people and equipment.

2.6.1.14 Machinery working or moving near power transmission lines must ensure the distance from the edge of the machine or load to the nearest power line is not less than the values in Table 2.

Table 2 – Distance from the edge of the machine or load to the nearest power line

Voltage of power transmission line, kV11 ÷ 2035 ÷ 110154 ÷ 220300500 ÷ 700Horizontal distance, m1.524569

2.6.1.15 Machinery working near trenches and pits must ensure the distance from the nearest support point of the machine to the trench or pit is not less than the values in Table 3.

Table 3 – Distance from the nearest support point of the machine to the trench or pit

Depth of pit mSoil typeSandSandy soilClay soilClayHorizontal distance from the nearest support point of the machine to the foot of the slope of the trench or pit (m)11.51.2511232.421.5343.63.251.75454.443.0565.34.753.5

In case the site conditions do not allow meeting the above requirements, there must be measures to reinforce against trench and pit collapses, when the load is at its maximum.

2.6.1.16 When moving machinery under operating power transmission lines, the distance from the highest point of the machine to the lowest point of the power line must be ensured to be not less than the values given in Table 4.

Table 4 – Distance from the highest point of the machine to the lowest point of the power line

2.6.1.17 Machinery must not be used when:

• The usage period stated in the usage permit and inspection sheet for lifting equipment and pressurized equipment has expired;
• Safety devices are damaged or missing;
• Important parts are damaged or missing;
• Weather conditions cause a loss of safety;
• The voltage of the drive power source drops by more than 15%.

2.6.1.18 When machinery is operating, the operator is not allowed to leave and go elsewhere or let others operate or be present in the cabin.

2.6.1.19 For hoists:

• They must be inspected after manufacture, after each installation or major repair, and periodically as prescribed;
• The steel structure of the hoist must be grounded;
• There must be a mechanism to automatically stop movement when loading and unloading goods and when the entrance and exit doors have not been closed by the operator. On the hoist, there must be a “Stop” button to stop movement in case of an incident. If the hoist is stopped due to an incident, everyone must wait for the rescue force, and must not climb out on their own;
• When stopping work, the hoist must be lowered to the lowest position, the drive power source must be disconnected, and the entrance and exit doors must be locked;
• Hoist operators and users must wear neat protective clothing, must not use scarves, and women must wrap their hair neatly under their hats.

2.6.1.20 The danger zone below an operating hoist must be fenced off and have signs prohibiting people from passing through.

2.6.1.21 If using iron hooks to drag and unload goods, the hook must have a length of not less than 1.8 m. The hook end on the worker’s hand side must be flat, smooth, and not bent.

2.6.1.22 The hoist must be safely shielded from all sides. The shielding height for hoists transporting people must not be less than 1.1 m, for hoists not transporting people must not be less than 0.5 m and must be at least 0.1 m higher than loose material goods.

2.6.1.23 Goods loaded on the hoist must be neat, must not exceed the dimensions of the hoist and must be firmly tied, the parts of the hoist must be braked to not shift during transport. Hot molten bitumen transported on the hoist must be contained in containers.

2.6.1.24 Machinery operators must meet the prescribed standards. When using machinery, they must fully comply with the provisions in the machinery safe operating procedures.

2.6.2 Inspection and maintenance

2.6.2.1 Before putting machinery into operation, the technical condition of the machinery, the condition of the construction ground and the operator’s field of vision must be checked. Machinery is only used when the technical condition of the equipment and the construction ground conditions meet requirements.

2.6.2.2 Construction machinery must be technically maintained and repaired periodically in accordance with the provisions in the technical documents.

2.6.2.3 Machinery technical maintenance, adjustment and repair is only allowed to be carried out after the engine has been stopped, the pressure in the hydraulic and compressed air systems has been discharged, and the working parts have been placed in a safe position. Particularly for lifting equipment, it must be re-inspected after each incident or disassembly, repair, and replacement of important parts.

2.7 Drilling work

2.7.1 There must be measures to ensure the safety of workers such as: measures to raise and lower the drill string, equipping safety belts, shielding to prevent heavy objects from falling from above. Do not perform work overhead when it is heavily raining, thunderstorms or winds of level 5 or higher. When it is dark or at night, there must be lights to illuminate the workplace.

2.7.2 When raising, lowering or repairing the drilling tower, those who do not have duties must leave the working area, staying at a distance of at least 1.5 times the height of the tower from the drilling tower.

2.7.3 When moving the drilling machine, the drill string must be lowered, except when moving on a flat road surface, the travel distance does not exceed 100 m. Moving drilling towers taller than 12 m must use cables to secure from 4 sides and tie at a height of 2/3 to 3/4 of the tower height. The distance from the tower to the person operating the winch to pull the tower must be ensured to be at least equal to the height of the tower plus 5 m. When temporarily stopping the move, the guy ropes must be anchored.

2.7.4 The distance between the drilling machine and the wall of the drilling tower must not be less than 1 m. If that distance cannot be ensured, a protective shield must be made.

2.7.5 The distance between the drilling tower and other structures must be determined according to the technical construction method design. The distance between drilling towers placed close to each other must be at least equal to 1.5 times the height of the tallest drilling tower.

2.7.6 Around each drilling tower, there must be supports to prevent the drill string from falling over. There must be stairs for workers to go up and down the tower. The stairs and working platforms on the drilling tower must have protective handrails around them at a height of 1 m. If handrails cannot be made, workers must wear safety belts.

2.7.7 After installing the drilling tower, the guy ropes must be fixed. The guy ropes must be firmly fixed to the anchors according to the requirements in the technical construction design. Adjusting the drilling tower is only allowed when all the guy ropes have been fully arranged according to the above requirements.

2.7.8 Before proceeding with drilling, the tower and equipment must be checked according to the following requirements:

• The firmness of the anchors;
• The stability of the joints on the tower;
• The stability of the platforms and supports;
• The eccentricity of the drilling tower;
• When the support posts or tower columns are deformed (dented, bent, warped, cracked…) or the anchors and clamps are damaged, they must be repaired to ensure safety before drilling can proceed;
• Before starting formal drilling, a trial drilling must be conducted and a report confirming the technical condition of the drilling machine must be made.

2.7.9 In addition to periodically checking the technical condition of the equipment, the drilling tower must be checked in the following cases:

• Before and after moving the drilling tower;
• Before and after troubleshooting;
• After stopping work due to thunderstorms and winds of level 5 or higher;
• After drilling into an air pocket.

2.7.10 Workers must not be on the drilling tower when the drill string is being raised or lowered. Only when there is a signal from the commander can the drill string be raised or lowered. The signals must be uniformly defined and disseminated to everyone before construction.

2.7.11 Drilling towers must have a lightning protection system. Electrical equipment must be protectively grounded.

2.7.12 When stopping work, the drill hole must be securely covered. On the cover or fence, signs and signal lights must be hung.

2.8 Scaffolding, supports and ladders

2.8.1 General requirements

2.8.1.1 All types of scaffolding and supports must be designed, constructed, installed, accepted and maintained to ensure safety. Pay attention to the instructions, regulations, and technical requirements written or accompanied with the manufacturer’s certificate of specialized scaffolding.

2.8.1.2 Scaffolding, supports, and ladders must not be used for purposes other than their intended use. Scaffolding and supports that are installed in combination from different types and forms or using multiple types without a separate design must not be used.

2.8.1.3 Scaffolding must not be supported on inclined planes when there are no technical measures to prevent the support posts from slipping.

2.8.1.4 Scaffolding and supports must not be used when:

• The scaffolding and supports are made of materials that do not meet the technical requirements according to the applicable standards;
• They do not meet the technical requirements and occupational safety conditions stated in the design or in their manufacturer’s certificate; especially when lacking hooks, anchoring ropes or they are anchored to unstable structural parts such as handrails, eaves, balconies… as well as to positions that have not been calculated to withstand the anchoring force;
• They are deformed, cracked, worn, rusted or missing parts;
• The gap between the working platforms and the building or structure walls is greater than 5 cm when building and greater than 20 cm when finishing;
• The distance from the edge of the scaffolding or support’s working limit to the adjacent edge of the transport vehicle is less than 60 cm;
• The scaffold posts and support frames are placed on unstable foundations, with the possibility of slipping or collapsing, or placed on building or structure parts without being fully considered and calculated to ensure stable load-bearing for that part or structure itself and for the scaffold post or support frame.

2.8.1.5 Loads must not be placed on scaffolding and supports outside the prescribed positions (where there is a sign clearly stating the allowable load above) or exceed the load according to the design or manufacturer’s certificate. Any type of load must not be placed or stored on the scaffolding ladders or working platforms.

2.8.1.6 When the scaffolding is higher than 6 m, at least two working platforms must be made, including the working platform above and the protective platform below. When working simultaneously on two platforms, the position between these two platforms must have a protective platform or net. Working simultaneously on two working platforms in the same bay without safety measures is not allowed.

2.8.1.7 When the scaffolding is higher than 12 m, stairs must be made in a scaffold bay. The slope of the stairs must not be greater than 60°. The opening on the working platform for going up and down must have safety handrails on all three sides.

2.8.1.8 The width of the scaffolding working platform must not be less than 1 m. When transporting materials on the working platform by hand carts, the platform width must not be less than 1.5 m. The wheel travel path must be planked; the plank ends must be tight and firmly attached to the working platform.

2.8.1.9 Wooden planks for working platforms must not be rotten, worm-eaten or cracked and must be designed to ensure load-bearing capacity and stability.

2.8.1.10 When working platforms must be made according to the provisions of 2.2.2.6, there must be handrails at least 1 m high and at least 2 horizontal bars capable of preventing people from falling.

2.8.1.11 Passageways underneath scaffolding and supports must have protective shielding above.

2.8.1.12 Scaffolding and supports near excavation pits, walkways, near the operating range of cranes must have measures to prevent the pit walls from collapsing or transport vehicles from colliding, causing the scaffolding and supports to fall or break.

2.8.1.13 When installing and using scaffolding and supports near power transmission lines (under 5 m, including low-voltage lines), very strict measures must be taken to ensure electrical safety for workers.

2.8.1.14 On scaffolding and supports with lighting and power-consuming equipment installed and used, the provisions of 2.3 and 2.5 must be strictly followed.

2.8.1.15 Scaffolding and supports with a height of up to 4 m are only allowed to be put into use after being accepted by a technical officer and recorded in the construction diary; those higher than 4 m are only allowed to be used after being accepted according to the regulations on quality management.

For slip formwork, working platforms, protective handrails, ladders and wind barriers must be firmly attached to the formwork system. The steel rods supporting the jacks must be designed and calculated, and the rod part above the concrete block must be braced to ensure stability. Jacks and lifting equipment must be equipped with pins or automatic braking devices to prevent slipping.

2.8.1.16 Every day, before working, the technical officer must re-check the condition of all structural parts of the scaffolding and supports. During work, any worker who detects a dangerous damage condition of the scaffolding or supports must stop working and report it to the technical officer for repair and supplementation.

2.8.1.17 After stopping construction on the scaffolding and supports for a long time (over one month), if wanting to continue construction, re-acceptance must be carried out according to the provisions of 2.8.1.15.

2.8.1.18 Dismantling scaffolding and supports must be carried out according to the instructions in the design or manufacturer’s certificate. The area being dismantled must have fences, signs prohibiting people and vehicles from passing through. Scaffolding and supports must not be dismantled by pulling them down.

2.8.1.19 Installing, dismantling or working on scaffolding and supports when it is heavily raining, thunderstorms or winds of level 5 or higher is not allowed. When the rain stops, before returning to work, the scaffolding and supports must be checked according to the provisions of 2.8.1.16 and there must be anti-slip measures.

2.8.2 Bamboo scaffolding, wooden scaffolding

2.8.2.1 Bamboo used for structures and scaffolding must be mature bamboo that is not rotten, worm-eaten or crushed, and must meet the technical requirements of current regulations.

2.8.2.2 Wood used for scaffolding must be from wood group 5 or higher according to current regulations, not warped, rotten, worm-eaten, cracked or broken.

2.8.2.3 Wooden scaffolding with a height greater than 4 m or bearing heavy loads must use bolt connections. Bamboo scaffolding must be tied with durable, slow-rotting ropes. Nails must not be used to connect bamboo scaffolding.

2.8.2.4 The feet of bamboo scaffold posts must be buried 0.5 m deep and firmly compacted.

2.8.2.5 After erecting bamboo and wooden scaffolding, the following must be checked: The anchoring ability of the joints, the material quality, the structural parts (handrails, stairs, platform planks…).

2.8.3 Steel scaffolding

2.8.3.1 The steel pipes used for scaffolding and the types of connecting steel bands must not be bent, flattened, dented, cracked, punctured or have other defects. The steel scaffolding structure must meet the technical requirements according to current regulations.

2.8.3.2 The feet of the scaffold posts must be inserted into the base and stably and firmly supported.

2.8.3.3 The scaffolding must be firmly anchored to the structure during installation. The position of the anchor hooks must be designed. When the position of the anchor hooks coincides with the wall holes, an internal bracing system must be made for anchoring, the steel bands must be firmly connected to prevent the girders from sliding on the vertical posts.

2.8.3.4 When installing and dismantling steel scaffolding near power lines (under 5 m), the provisions of 2.8.1.13 must be followed.

2.8.3.5 When erecting scaffolding higher than 4 m, a lightning protection system must be made according to the design instructions. Except for the case where the scaffolding is erected within the scope protected by an existing lightning protection system.

2.8.4 Suspended scaffolding, suspended baskets

2.8.4.1 The cross-section of the suspension ropes must follow the design instructions and must ensure a safety factor of not less than 6.

Suspended scaffolding must use steel suspension ropes.

2.8.4.2 Suspended scaffolding and suspended baskets must be installed at a minimum distance of 10 cm from the projecting parts of the structure.

2.8.4.3 Consoles must be fixed to firm structural parts of the structure. They must not be supported on eaves or roof edges.

2.8.4.4 Suspended scaffolding must be firmly anchored to the structure.

2.8.4.5 When going up and down suspended scaffolding, workers must use rope ladders firmly fixed to the consoles or through wall openings.

2.8.4.6 Before using suspended scaffolding, it must be retested with a static load with a value greater than 25% of the calculated load. For suspended baskets, before use, in addition to testing with a static load as above, they must also be tested with the following types of loads:

a) The load of the suspended basket when lifting and lowering with a value greater than 10% of the calculated load.

b) The suspended load and hook with a value greater than 2 times the calculated load and the test suspension time on the rope is at least 15 min.

2.8.4.7 When raising and lowering suspended baskets, a winch with automatic brakes must be used. Free falling is not allowed. When stopping work, the suspended basket must be lowered.

2.8.5 Mobile lifting towers

2.8.5.1 The path of travel for mobile lifting towers must be level both longitudinally and laterally.

2.8.5.2 Once positioned, mobile lifting towers must have their wheels chocked and brakes securely engaged. Mobile lifting towers must be equipped with lightning protection systems as specified in the design.

2.8.5.3 Mobile lifting towers must be moved smoothly without jerking. Mobile lifting towers must not be moved in winds of level 5 or higher, or when there are people or materials on the working platform.

2.8.6 Cantilever scaffold supports

2.8.6.1 The frames of scaffold supports must be placed on a flat and stable foundation. When the floor structure has not yet been completed, temporary planks must be placed on the beams to support the scaffold frames; the scaffold frames must not be placed directly on the floor beams.

2.8.6.2 Scaffolds supports can only be stacked up to two frames high. If stacking three frames high is desired, the load on the working platform must be limited or reinforcement measures must be implemented. In both cases, the load-bearing capacity of the scaffold support must be recalculated and verified. The frames on the upper level must be anchored to solid structural components of the building.

2.8.6.3 When ascending or descending the working platform of the scaffold support, workers must use a leaning ladder and must not hold onto the frame to climb up or down.

2.8.6.4 Cantilevers must be securely connected to the structural components of the building.

2.8.6.5 When transferring materials to the working platform, a material hoist or other lifting devices must be used. Lifting devices must not be connected to the cantilevers. When ascending or descending the cantilever working platform, workers must go from inside the building through wall openings.

2.8.7 Ladders

2.8.7.1 Ladders must be placed on a flat, stable surface and securely chocked. Ladders must not lean at an angle greater than 60° or less than 45° from the horizontal plane. If a ladder is placed contrary to this regulation, someone must hold the ladder and the ladder base must be securely chocked.

2.8.7.2 When extending a ladder, it must be securely tied with ropes; the top of the ladder must be anchored to the structure.

2.8.7.3 Before working on a folding ladder, ropes must be tied to prevent the ladder from splaying out.

2.8.7.4 Before using a ladder, its overall safety condition must be inspected. For new ladders or ladders that have been unused for a long time, they must be tested with a load of 120 daN before use.

2.8.7.5 Before allowing people to climb a ladder, the ladder chocks and support points must be rechecked.

2.8.7.6 Heavy objects exceeding the allowable load must not be suspended from the ladder while someone is working on it. Folding ladders must not be used as scaffolding or supports.

2.9 Welding work

2.9.1 General requirements

2.9.1.1 Before each work shift, welders must inspect all equipment, tools, welding materials, and firefighting equipment to ensure that the tools and equipment are in good working order, the joints are tight, and the materials are of the correct type.

2.9.1.2 On floors where electric or gas welding is being performed, as well as the floors below (when there is no fire-resistant protective flooring), combustible and explosive materials within a radius of not less than 5 m must be cleared away, and materials and equipment with explosive potential must be moved elsewhere.

2.9.1.3 Measures must be taken to prevent collapse when cutting structural components.

2.9.1.4 Flame cutting of pressurized equipment or equipment containing flammable, explosive, or toxic substances is not permitted.

2.9.1.5 When electric or gas welding inside closed tanks or rooms, proper ventilation must be provided; the wind speed must be between 0.3 m/s and 1.5 m/s; an outside observer must be stationed to promptly handle any dangers. When welding using liquefied gases (propane, butane, and carbon monoxide), the intake of the ventilation system must be located at the bottom. Fume extraction ducts, blowers, or masks must be used to avoid inhaling welding fumes.

2.9.1.6 Before welding or cutting equipment that previously contained flammable liquids or acids, it must be thoroughly washed, dried, and then inspected to ensure that their concentrations are lower than hazardous levels before proceeding with the work.

2.9.1.7 Before welding in areas with flammable, explosive, or toxic vapors or gases, the concentrations of those vapors and gases must be checked, and measures must be taken to ensure fire and explosion safety in accordance with current regulations. If necessary, ventilation must be carried out to ensure there is no risk of fire, explosion, or toxicity before starting work.

2.9.1.8 Gas and electric welding must not be performed simultaneously inside closed tanks.

2.9.1.9 When welding inside closed tanks, the lighting must be placed outside or portable hand-held lamps with a voltage not exceeding 12 V must be used. An isolation transformer must be used for lighting and placed outside. Auto-transformers must not be used for voltage reduction.

2.9.1.10 Gas and electric welders, including welding assistants, must be equipped with masks or shields with appropriate welding lenses. Before welding, welders must check all safety conditions.

2.9.1.11 Welding at heights is only allowed after fire prevention measures and safety measures for materials, equipment, and people working and moving below have been implemented.

2.9.1.12 Welding or cutting electrical components or near operating electrical equipment requires measures to prevent electric shock.

2.9.2 Electric welding

2.9.2.1 Electrical connections from the power grid to the welding machine must go through a switch and fuse. The welding machine must have an electrical on/off device. When not in use, the power supply to the welding machine must be cut off. The use of electric welding machines and electric welding work must comply with QCVN 03: 2011/BLĐTBXH.

2.9.2.2 The metal parts of electric welding equipment (alternating current welding machine housing, direct current welding machine, etc.) as well as the welded structures and products must be grounded for protection.

2.9.2.3 To transmit welding current to the electric welding clamp or torch, flexible insulated cables with a cross-section suitable for the maximum current of the welding equipment and the extended duration of a welding cycle must be used.

2.9.2.4 Connections between electrical cables must be made by welding and insulated. The connection of electric cables to the welding equipment must be made with copper lugs, bolted, and soldered tightly to the welding equipment.

2.9.2.5 When moving or placing welding cables, care must be taken to avoid damaging the insulation sheath. Electrical cables must not come into contact with water, oil, steel cables, or high-temperature pipelines. The distance from welding cables to high-temperature pipelines, oxygen cylinders, acetylene gas cylinders, or other flammable gas cylinders must not be less than 5 m. The length of the cable from the power source to the welding machine must not exceed 15 m.

2.9.2.6 The minimum cross-section of the return conductor must ensure safety according to the heating conditions caused by the welding current passing through it. The connection between the parts used as the return conductor must be secure by clamping, bolting, or welding. When welding in rooms with a risk of fire or explosion, the return conductor must be insulated like the main cable.

2.9.2.7 The handle of the welding clamp must be made of insulating and heat-resistant materials. The welding clamp must firmly grip the welding rod. For welding currents with an intensity of 600 A or more, welding clamps with cables running through the handle must not be used.

2.9.2.8 The voltage at the terminals of direct current welding machines and alternating current welding machines during arc generation must not exceed 110 V for direct current machines and 70 V for alternating current transformer machines.

2.9.2.9 Fixed contact welding machines must use single-phase transformers and be connected to a 50 Hz alternating current grid with a voltage not exceeding 50 V. The no-load voltage must not exceed 36 V.

2.9.2.10 Arc power must only be taken from alternating current welding machines, direct current welding machines, or rectifiers. It must not be taken directly from the power grid.

2.9.2.11 Cables must not be connected or disconnected at the output of the welding machine when it is still energized.

2.9.2.12 When welding inside metal closed tanks, the welding machine must be placed outside; the welder must be equipped with a rubber helmet, insulated shoes or mats, and rubber gloves.

2.9.2.13 Welding machines placed outdoors must have a rain cover. Welding must not be performed outdoors during rain or storms.

2.9.2.14 Welding in areas with many people working together or in areas with high foot traffic must have shielding screens made of non-combustible materials to isolate and protect the surrounding people.

2.9.2.15 Contact welding machines of the welding joint type must be equipped with transparent glass shielding plates for workers to observe the welding process.

2.9.2.16 Cleaning of electrodes on electric welding machines and seam welding machines is only allowed after the power has been cut off.

2.9.2.17 Seam welding machines that use water to cool the rollers must have a trough to collect the water. When working, workers must stand on a platform with an insulating rubber mat.

2.9.2.18 Electric welding machines and seam welding machines must have glass plates installed to shield the electrodes on the side where the welder stands to work.

2.9.2.19 Only trained welders are allowed to perform underwater welding.

2.9.2.20 Before carrying out underwater welding work, the structure to be welded must be thoroughly surveyed; a construction plan must be prepared and carefully approved.

2.9.2.21 When welding underwater, there must be a person well-versed in safety techniques on the water surface to supervise and communicate with the person welding underwater via telephone. The telephone, switch, and power cutoff switch must be placed in a convenient position for prompt handling of incidents.

2.9.2.22 If there is an oil or grease film on the water surface in the welding area, the welder must not be allowed to go underwater to work.

2.9.3 Gas welding

2.9.3.1 In addition to the provisions in this section, gas welding and cutting must also comply with the requirements of the technical standards selected for application to the project.

2.9.3.2 Calcium carbide must be stored in sealed containers; kept in a dry, cool, and well-ventilated place; and protected from fire. When opening a calcium carbide container, specialized tools must be used.

2.9.3.3 When using an acetylene gas generator, it is not allowed to:

– Allow the gas pressure to exceed the permitted limit;

– Remove automatic control devices, safety valves, or pressure gauges;

– Use damaged or inaccurate safety devices;

– Open the calcium carbide compartment cover without completely releasing the remaining gas in the generator;

– Place the generator in walkways, near stairs, in basements, or in crowded areas without protective measures in case of explosion.

2.9.3.4 Acetylene gas generators must have a flame arrester. The water level in the flame arrester must be checked before each use and at least twice per work shift.

2.9.3.5 Before cleaning an acetylene gas generator, all openings (nozzles, doors, etc.) must be opened for ventilation.

2.9.3.6 When grinding calcium carbide, goggles and a mask must be worn. When removing the remaining calcium carbide from the gas generator, rubber gloves must be worn.

2.9.3.7 Gas cylinders must be sorted and stored separately from empty cylinders. Gas cylinders must be stored upright in racks and secured with chains, hooks, or locking straps.

2.9.3.8 Only cylinders with all protective components can be accepted, stored, and delivered to consumers.

2.9.3.9 Acetylene gas cylinders are painted white, with the word “ACETYLENE” written on the cylinder in red. Oxygen cylinders are painted sky blue, with the word “OXYGEN” written on the cylinder in black.

2.9.3.10 Oxygen and acetylene cylinders used for welding must be placed in a cool, dry, well-ventilated area with a roof to protect against rain and sun, away from exposed electrical wires or heated objects. When moving, they must be placed on specialized cylinder carts. The distance between oxygen and acetylene cylinders (or acetylene gas generators), as well as the distance between them and the welding area, open flames, or areas prone to sparks, must be at least 10 m.

2.9.3.11 When transporting and using oxygen cylinders:

– They must not be carried on the shoulder or rolled on the ground;

– Transport vehicles with shock-absorbing components must be used;

– For long-distance transportation, cylinders must be placed horizontally in the vehicle, and each cylinder must have 2 rubber or fiber cushioning rings with a diameter of 25 mm;

– Oil and grease must not be applied to the threaded fittings. Hands with oil or grease must not touch the cylinders.

2.9.3.12 When in use, depending on the ambient temperature, a minimum pressure must be maintained in the cylinder:

– 50 kPa for oxygen cylinders;

– 330 kPa for acetylene gas cylinders.

2.9.3.13 Specialized tools must be used to open acetylene generator valves, oxygen cylinder valves, and install pressure regulators on the cylinders. Pressure regulators without pressure gauges or with inaccurate gauges must not be used. Gauges must be calibrated as prescribed.

2.9.3.14 Before welding or cutting with gas, welders must check the gas hoses, torches, gas cylinders, gauges, and gas generators.

2.9.3.15 When igniting the torch, the oxygen valve must be opened first, then the acetylene valve. When stopping welding, the acetylene valve must be closed first, then the oxygen valve.

2.9.3.16 Welding in buildings under construction or in rooms where equipment is being installed requires local ventilation.

2.9.3.17 If the welding torch becomes clogged during welding, a copper wire must be used to clear it; hard steel wire must not be used.

2.9.3.18 Acetylene hoses, oxygen hoses, or nuts on cylinders under pressure must not be repaired or tightened when the pressure gauge has not been set to 0.

2.10 Workshop layout and machine usage

2.10.1 Sparks must not be generated in areas prone to fire. These areas must have “No Fire” signs.

2.10.2 Acid and alkaline solutions must not be discharged into public pipelines; these solutions must be discharged through separate pipelines.

2.10.3 Wooden platforms must be provided at frequently wet work locations.

2.10.4 Walkways between internal workshop areas must be at least 0.8 m wide. No objects should obstruct the walkways.

2.10.5 Adequate lighting must be provided in walkways, stairs, and work locations when it is dark. Lights must be arranged so that they do not shine directly into workers’ eyes, are not too bright, do not flicker, and do not have light intensity changes that may affect workers’ operations.

2.10.6 All machine controls must be placed in safe and easily accessible positions.

2.10.7 Machines must be positioned so that during disassembly or repair, they do not affect adjacent machines or workers’ operations.

2.10.8 All machine safety mechanisms must be fully installed and ensured to function properly. Machine tools must not be tested or operated without all safety mechanisms installed.

2.10.9 Before repairing belt-driven machines, the belt must be removed from the pulley.

2.10.10 For high-mounted moving parts that require regular monitoring and adjustment, an operating platform at least 0.9 m wide with a 1 m high protective railing must be provided.

2.10.11 Machines using electric motors or equipped with lighting must have protective grounding.

2.10.12 Machines must not be lubricated while in operation.

2.10.13 Power to machines must be cut off in the following cases:

– When stopping work, even for a short time;

– When there is a power outage;

– When cleaning the machine or lubricating it.

2.10.14 Machines must be stopped in the following cases:

– When removing a workpiece from the machine if it is not equipped with an automatic ejection mechanism while the machine is running;

– When changing tools or equipment.

2.10.15 When machining, if there are metal chips or sparks flying out, a protective screen must be provided. If a protective screen cannot be installed, workers must be fully equipped with personal protective equipment in accordance with current regulations.

2.10.16 At work locations with dust generation, dust extraction equipment must be provided to ensure that the dust concentration does not exceed permissible limits.

2.10.17 If abnormal phenomena are detected while a machine is running, it must be stopped.

2.10.18 When electrical equipment is damaged, the power must be cut off and an electrician must be immediately notified for repairs; unauthorized repairs must not be attempted.

2.10.19 When work is finished, the machine must be turned off and can only be left after it has been thoroughly cleaned and carefully inspected.

2.11 Use of bitumen, mastic, and insulation layers

2.11.1 Bitumen, mastic

2.11.1.1 Preparation

2.11.1.1.1 Areas for preparing and heating bitumen and mastic must be located at least 50 m away from flammable structures and must be fully equipped with firefighting equipment.

2.11.1.1.2 Tools and equipment for preparing and heating bitumen and mastic must meet the following requirements:

– Heating tanks must have lids made of non-combustible materials and be tightly covered. Bitumen or mastic must not be filled beyond 3/4 of the tank’s capacity;

– Tanks with leaks must not be used for heating.

2.11.1.1.3 Before removing bitumen from a drum for heating, the drum must be tilted to allow any water to drain out completely.

2.11.1.1.4 Bitumen added to the heating tank must be dry; during the preparation and heating of bitumen and mastic, water must not be allowed to drip into the heating tank.

2.11.1.1.5 Wet bitumen must not be added to a tank of hot molten bitumen.

2.11.1.1.6 When using liquid fuels (kerosene, mazut oil, etc.) to heat bitumen for roof waterproofing, the heating furnace may be placed on the roof if there is no risk of igniting the structure.

2.11.1.1.7 When bitumen needs to be mixed with gasoline or oil, the following requirements must be met:

– During mixing, workers must stand upwind and slowly pour the bitumen into the gasoline or oil while gently stirring with a wooden rod. Gasoline or oil must not be poured into hot molten bitumen;

– The temperature of the bitumen during the mixing of the solution must be at least 30°C lower than the auto-ignition temperature of the mixing solvent;

– The bitumen mixing area must be well-ventilated and at least 20 m away from open flames.

2.11.1.2 Transportation

2.11.1.2.1 Tools for scooping and containing hot molten bitumen and mastic must be dry and sturdy. A long-handled ladle must be used to scoop hot molten bitumen and mastic.

2.11.1.2.2 When transporting hot molten bitumen and mastic, the following requirements must be met:

– Hot molten bitumen and mastic must be transported to the construction site using mechanical means in metal containers with tightly closed lids; they must not be filled beyond 3/4 of the container’s capacity;

– Hot molten bitumen and mastic containers can only be transported by manual means when mechanical means cannot be used.

2.11.1.2.3 Mechanical means must be used to transport hot bitumen containers to elevated locations.

2.11.2 Insulation layers

2.11.2.1 When spreading bitumen, workers must walk backwards against the wind direction. Workers must wear full personal protective equipment: masks, gloves, and rubber boots. Unauthorized personnel must not approach the bitumen spreading area.

2.11.2.2 When spreading bitumen on roofs, measures must be taken to prevent hot molten bitumen from falling onto people below.

2.11.2.3 Before starting to install insulation layers for technological equipment, the electric motors of that equipment must be completely disconnected, and the steam supply and technological solution inlets must be securely plugged. Signs indicating that work is in progress must be placed at these locations.

2.11.2.4 The installation of insulation layers for technological equipment and pipelines must be carried out directly on the ground before their installation or after they have been fixed in place according to the design.

2.11.2.5 When applying insulation layers using paint or hot molten bitumen in confined spaces, wells, trenches, etc., workers must use masks, protective goggles, and apply special oil or ointment to exposed parts of the body.

2.11.2.6 After temporarily stopping or completing the above work, signs must be placed prohibiting people from approaching these areas. Entry for further work is only allowed when authorized by a responsible person and when the concentration of toxic substances in the air has decreased to at least the permissible limit.

2.11.2.7 When installing insulation layers using mineral wool, fiberglass, or similar materials, workers must use protective goggles, gloves, and masks. Work clothes must have collars and sleeves securely fastened.

2.11.2.8 When installing fiberglass insulation near operating power lines, the power must be cut off.

2.12 Earthwork

2.12.1 General requirements

2.12.1.1 The provisions of this section apply to excavation work for foundation pits and open trenches in construction projects.

2.12.1.2 Excavation of foundation pits and trenches is only permitted according to the approved construction method design documents.

2.12.1.3 When excavating in areas with underground utilities (underground cables, water pipes, steam pipes, etc.), written approval from the management agency of those utilities must be obtained, along with a diagram indicating the location and depth of the utilities. The construction unit must place appropriate signs and signals in the area with underground utilities and must assign a technical supervisor during the entire excavation process.

2.12.1.4 Machines and tools that cause strong impacts, such as crowbars, pickaxes, chisels, and compressed air equipment, must not be used to excavate near underground utilities. If unfamiliar underground utilities or objects not matching the guidance diagram are discovered, or if obstacles such as bombs, bullets, or mines are encountered, work must be immediately stopped for examination and appropriate handling measures. Work can only be resumed after safety measures have been implemented.

2.12.1.5 When excavating near operating underground power cables, if power cannot be cut off, measures must be taken to ensure electrical safety for workers (using insulated tools, wearing insulated protective equipment), and direct supervision by the underground power cable management agency must be provided during excavation.

2.12.1.6 If vapors or toxic gases are detected during excavation, work must be immediately stopped, and workers must leave the hazardous area until measures are taken to eliminate the toxic vapors and gases.

2.12.1.7 Excavation of foundation pits, trenches, etc., near walkways, traffic routes, or in residential areas must have fences and warning signs, and red lights must be used at night. Fences must be placed at least 1 m away from the outer edge of the roadside.

2.12.1.8 In areas under excavation, measures must be taken to drain stagnant water (including during heavy rain) to prevent water from flowing into the excavation pit and causing the pit walls to collapse.

– During excavation, water in foundation pits and trenches must be completely pumped out to prevent soil collapse.

– When the groundwater level is higher than the foundation pit bottom elevation, measures must be taken to stabilize the excavation pit and prevent soil uplift at the pit bottom (lowering the groundwater level, installing support systems, etc.).

2.12.1.9 In areas with low soil moisture and no groundwater, excavation of foundation pits and trenches with vertical walls (without wall support) can be carried out to a depth of:

– No more than 1 m for soft soil that can be excavated with a shovel;

– No more than 2 m for hard soil that requires excavation with crowbars, pickaxes, or chisels.

2.12.1.10 In all excavation conditions other than those specified in 2.12.1.9, excavation must be carried out with sloped walls or wall support.

2.12.1.11 If natural conditions or external factors change the soil condition during excavation, such as prolonged rain soaking the foundation, excessively moist or saturated soil, etc., the construction unit must recheck the excavation pit walls and slopes. If safety is not ensured, measures must be taken to reinforce and prevent sudden slippage, soil collapse, or wall collapse (reducing slope inclination, temporarily stopping soil transportation, reinforcing support members, etc.).

2.12.1.12 When excavating foundation pits or trenches with sloped walls or wall support, it is not allowed to place loads in the wrong location, area, or type specified in the technical construction design, such as stacking materials, dumping excavated soil, placing machines, rails, or tracks, moving vehicles, erecting power poles, etc., in the wrong place or position specified in the design.

2.12.1.13 Excavation using the “frog mouth” method is not allowed. If underground objects are discovered, work must be stopped immediately, and workers must move to a safe location. Work can only resume after the “frog mouth” or underground object has been removed.

2.12.1.14 The condition of excavation pit walls and slopes must be regularly inspected. If cracks are detected along the foundation pit walls or slopes, work must be stopped immediately. Personnel, as well as machinery and equipment, must be moved to a safe location. Work can only resume after appropriate remedial measures have been taken.

2.12.1.15 When excavating foundation pits or trenches within the range of influence of machines and equipment causing strong vibrations, measures must be taken to prevent damage to the slopes.

2.12.1.16 In excavation areas with trees, measures must be taken to safely cut trees and remove stumps. Before cutting trees, an audible warning signal must be given to alert the hazardous area. When using machines to remove tree stumps, measures must be taken to prevent the pulling cable from breaking.

2.12.1.17 The use of explosives to remove rock masses, old building foundations, or loosen excessively hard soil masses must comply with the provisions of QCVN 02: 2008/BCT.

2.12.1.18 Steps for accessing foundation pits must be at least 0.7 m long and 0.4 m wide. When the excavation pit is narrow and deep, a leaning ladder must be used. Grabbing the wall support members or placing hands on the edge of the excavation pit for entry and exit is not allowed.

2.12.1.19 When lifting soil using buckets, containers, etc., from foundation pits or trenches, a sturdy protective roof or net must be provided to ensure the safety of workers. When raising or lowering buckets, containers, etc., appropriate signals (sound, light, etc.) must be used to avoid accidents.

2.12.2 Excavation with sloping sides

2.12.2.1 Excavation of foundation pits and trenches different from the provisions in 2.12.1.8 and 2.12.1.9 must create slopes (if not shoring the walls) with angles not greater than the values in Table 5.

Table 5 – Slope angles for unshored excavations

2.12.2.2 Excavation of saturated sand or sandy loam without a shoring system is not allowed.

2.12.2.3 For slopes longer than 3 m with a gradient greater than 1:1 or slopes with a gradient greater than 1:2 but moist or wet, workers on them must wear safety harnesses tied to securely anchored stakes.

2.12.3 Excavation with shoring

2.12.3.1 When excavating foundation pits or trenches without creating slopes as prescribed in 2.12.2.1, a shoring system must be installed according to the provisions in Table 6.

Table 6 – Shoring systems

2.12.3.2 For wide foundation pits, the shoring system must be designed and calculated.

2.12.3.3 When excavating foundation pits or trenches in wet places or sandy soil prone to collapse, tightly joined sheet piles driven at least 0.75 m into the excavation bottom must be used.

2.12.3.4 Excavation of foundation pits or trenches in flowing sand areas must have specially designed sheet shoring, which includes measures to reinforce the shoring walls and lower the groundwater level.

2.12.3.5 Excavation of foundation pits or trenches adjacent to old backfilled pits where the backfill is not yet stable must have measures to firmly reinforce the shoring walls and the shoring conditions must be regularly monitored during excavation.

2.12.3.6 If retrieving shoring struts in areas prone to collapse or adjacent to old structures that may destabilize the excavation walls or those structures, the struts must be removed in stages or the entire shoring system left in place.

2.12.3.7 When excavating soil by machine, a shoring system without struts must be used, or if not shoring the walls, slopes must be created as prescribed in 2.12.2.1.

2.12.4 Manual excavation

2.12.4.1 Using hoes, shovels or any other hand tools must comply with the provisions in 2.5. Particular attention should be paid to the provision in 2.12.1.5.

2.12.4.2 Soil excavated from the bottom of foundation pits or trenches must be dumped in areas and locations specified in the construction design, but at least 0.5 m away from the pit edge. Soil dumped at the pit edge must have a slope not exceeding 45o to the horizontal plane. When excavating soil on hillsides or mountainsides, measures must be taken to prevent sudden rolling of soil and rocks down the slope.

2.12.4.3 Drainage, inspection of sloped excavation walls, and the construction of access steps must comply with the provisions in 2.12.1.8, 2.12.1.11, and 2.12.1.18.

2.12.4.4 When excavating foundation pits or trenches deeper than 2 m, at least 2 workers must work together but stand far enough apart to be able to provide prompt rescue in case of sudden accidents.

2.12.4.5 Workers must not be assigned to work at the foundation pit edge while others are working below in the same compartment where soil or rock can fall or collapse onto those below.

2.12.4.6 Resting at the edge of excavations or on embankments is not allowed.

2.12.5 Machine excavation

2.12.5.1 Excavation by excavators

2.12.5.1.1 During machine operation, all people are prohibited from walking on natural slopes as well as within the operating radius of the machine. This area must have warning signs.

2.12.5.1.2 The machine base must be stable and level. If the ground is weak, sleepers must be laid and the machine must have secure chocks.

2.12.5.1.3 When operating and moving excavators, all general provisions in 2.6 must be fully implemented (checking machine condition, machine positioning, safety devices, brakes, signals, sounds, running the machine unloaded, handing over machine condition after each work shift, moving machines under high-voltage power lines).

2.12.5.1.4 The inclination of the excavator must not be changed while the bucket is carrying a load.

2.12.5.1.5 Brakes must not be adjusted while the bucket is carrying a load or swinging. Sudden braking is not allowed.

2.12.5.1.6 Excavators must not be operated while manually securing cables. Hands must not be used to straighten cables while using a cable winch.

2.12.5.1.7 The condition of cables must be regularly checked. Spliced cables must not be used.

2.12.5.1.8 When stopping work, the excavator must be moved away from the face and the bucket lowered to the ground. The bucket may only be cleaned when it has been lowered to the ground.

2.12.5.1.9 Excavators may only be allowed to work at night or in foggy conditions when adequate lighting is ensured.

2.12.5.1.10 In any case, the distance between the single-bucket excavator cabin and the excavation wall must not be less than 1 m.

2.12.5.1.11 When moving excavators on road sections with slopes greater than 15o, support from a tractor or winch is required. When moving, the bucket must not carry a load; the bucket must be positioned along the direction of machine movement, while lowering the boom from 0.5 m to 0.9 m above the ground.

2.12.5.1.12 When controlling the bucket to dump soil into a truck bed, the bucket must be swung over the back of the truck bed and stopped in the middle of the truck bed. Then the bucket is slowly lowered to dump the soil. The bucket must not be maneuvered over the cab. The driver must not sit in the cab while the excavator is dumping soil into the truck bed.

2.12.5.2 Excavation by bulldozers

2.12.5.2.1 When excavating soil with bulldozers, the machines’ operating range must be defined. All people are prohibited from walking or working on the machines’ travel paths, even when the machines are temporarily stopped.

2.12.5.2.2 Bulldozers must not be used for construction on slopes greater than 30o. The blade must not protrude beyond the edge of foundation pits or trenches (when dumping soil).

2.12.5.2.3 Machine operators must always comply with the following provisions:

– When the machine is moving, look ahead;

– Do not work at night or in the dark without adequate lighting;

– When stopping work, lower the blade onto the ground.

2.12.5.2.4 The minimum distance between two bulldozers (measured from the nearest edge between the two machines) working on the same surface is 2 m.

2.12.5.3 Excavation by scrapers

2.12.5.3.1 Excavation by scrapers must be at least 0.5 m away from foundation pits or trenches, or at least 1 m away from slopes.

2.12.5.3.2 Scrapers must not be used for construction on slopes greater than 30o.

2.12.5.3.3 Soil in the machine bowl must not be dumped while the machine is moving.

2.12.5.3.4 When the machine is moving, people must not stand between the machine bowl and tractor, or pass through the connection between the machine bowl and tractor.

2.12.5.3.5 When moving scrapers, the bowl must be lowered to at least 0.35 m above the ground.

2.12.5.3.6 Repairs or lubrication of any machine part is not allowed while the machine is operating.

2.12.5.3.7 The machine bowl must be detached from the tractor when workers repair parts under the machine bowl.

2.12.5.3.8 When using soil excavation machines such as excavators, bulldozers, scrapers, etc., in addition to the above provisions, the provisions in 2.6 must be followed.

2.12.6 Excavation of wells and test pits

2.12.6.1 Excavation of wells and test pits in conditions different from those specified in 2.12.1.9 must have shoring walls.

2.12.6.2 When excavating wells and test pits, the following provisions must be followed:

– Above the pit opening, there must be a steel mesh guard to prevent soil and rocks from falling into the pit from the opening;

– Buckets for transferring soil and rock from below must be securely tied to the end of the pull rope. When transferring rock blocks from the pit below, workers must exit the pit;

– Materials must not be loaded to overfill the bucket;

– Workers must exit the pit when transferring soil and rock from below if there is no protective roof;

– When working in wells and test pits, there must be at least 02 people or more to promptly prevent and handle incidents.

2.12.6.3 When there are people working in the pit, any work that may generate sparks in the pit is not allowed.

2.12.6.4 Workers descending into deep pits must use ladders or lifting buckets. The pull rope must be taken with a safety factor of 9 times the actual load, the reserve length of the pull rope must not be less than 6 winch drum turns, and the rotating winch must be securely fixed.

2.12.6.5 Before allowing workers to descend into the pit, it must be checked to ensure there are no toxic gases at the bottom. If there are toxic gases, workers must not be allowed to descend into the pit and measures must be taken to completely eliminate those toxic gases.

2.12.6.6 When using lifting buckets to raise and lower workers in wells or test pits, only hand winches may be used and the travel speed must not exceed 1 m/s, while being supervised by the technical construction manager in charge. The winch must have full automatic braking devices. The winch must be checked before each work shift and at least 2 times within a shift.

2.12.7 Hydraulic excavation

2.12.7.1 Water jet guns may only be connected to the water supply system after checking that the locking devices at the water supply source are working well.

2.12.7.2 Water jet guns must not be allowed to operate unattended.

2.12.7.3 When temporarily stopping work, the water nozzle must be directed diagonally downward and turned to a direction with no passing people.

2.12.7.4 The distance between the water jet gun placement and the face must not be less than the height of the face.

2.12.7.5 The condition of the water pipes from the pumping station to the water jet gun placement must be regularly inspected.

2.12.7.6 The water jet gun area must have fences and prohibition signs.

2.12.7.7 Before operating the water jet gun, the condition of the valves must be checked. On the water pipes within a range of no more than 10 m from the working position of the worker controlling the water jet gun, there must be a valve to stop the water supply in case of incidents.

2.12.7.8 Walking on water pipes is not allowed. Separate walkways must be built.

2.12.7.9 Nozzle replacement, tightening of joints, or repairs of water jet gun damage may only be done after turning off the engine.

2.12.7.10 At night, the operating range of the water jet gun must be adequately illuminated.

2.12.7.11 Workers controlling the water jet gun and workers at the pumping station must communicate with each other by sound or light signals.

2.12.7.12 Within the operating range of the water jet gun, if there are high-voltage power lines passing through, precautions must be taken against water streams or jets touching the wires or power poles.

2.12.7.13 Water pipes must not be placed on supports near high-voltage power lines.

2.12.7.14 Sludge chutes placed on supports must ensure strength and stability; both sides of the chute must have 0.7 m wide operating platforms and 1.0 m high protective railings. Sludge collecting funnels may only be cleaned when the water jet gun and sludge suction machine are turned off.

2.12.7.15 People and vehicles must not pass under sludge chutes and water pipes.

2.12.7.16 Sludge ditches and sludge storage pits must have firm protective walls. Walking on the protective walls is not allowed.

2.12.7.17 After stopping work, it is necessary to: signal to shut down the pumping station; close the valve at the water jet gun; suck all the sludge into the storage area.

Translating the provided technical content from Vietnamese to English, using formal language and correct terminology suitable for regulatory documents in the construction industry:

2.13 Foundation Works and Sinking Shafts

2.13.1 Shallow Foundation Construction

2.13.1.1 Materials (bricks, rocks, etc.) must not be dropped or thrown from the foundation pit edge into the pit. Mechanical means or chutes must be used to bring materials into the foundation pit; the lower end of the chute must be placed no more than 0.5 m from the foundation pit bottom.

2.13.1.2 Walkways and material transport routes must be located outside the potential collapse zone of the foundation pit.

2.13.1.3 The stability of the foundation pit walls must be checked before construction. During foundation construction, if there is a risk of pit wall collapse, people must quickly evacuate the danger zone.

2.13.1.4 Dedicated ladders must be used for entering and exiting foundation pits. Swinging, jumping, or using the strut system for access is not allowed.

2.13.1.5 Foundation materials must be placed 1 m away from the pit edge and must have a stop board.

2.13.2 Pile Foundation Construction

2.13.2.1 Wire ropes used for mechanical pile pulling must have a safety factor of not less than 6, and not less than 4 when pulling manually.

2.13.2.2 Before erecting piles, their quality must be checked to eliminate unsafe piles. People not assigned to the task must stand outside the pile erection area at a distance of at least the tower height plus 2 m.

2.13.2.3 Piles may only be pulled by wire ropes threaded through directional pulleys when these pulleys are vertically fixed to the machine base and the piles are within the operator’s line of sight.

2.13.2.4 When piles need to be readjusted, the hammer must be stopped and lowered close to the pile top. When adjusting the pile top, the hammer must be raised no more than 0.3 m from the pile top, while securing the hammer with ropes or pins.

2.13.2.5 When cutting off excess tops of concrete piles, safety measures must be taken to prevent concrete fragments from flying or the pile top from falling onto people.

2.13.2.6 When constructing cast-in-place piles:

• Construction and concreting of piles are not allowed in winds above level 5;
• Hole covers must be used when drilling is stopped;
• In cases where pile holes need to be dug manually: it is only allowed in stable soil, without groundwater, and the hole walls must be continuously supported;
• People are only allowed to work in drill holes with sufficient operating space and a diameter of at least 1.0 m;
• Hazardous locations must have warning signs and guards.

2.13.2.7 When constructing driven piles:

• For equipment using heavy objects as counterweights, safety measures must be established for installing, dismantling, and transferring counterweights;
• The hydraulic system operator must be in a position to observe all pile assembly, pile welding, guide pile installation, and other auxiliary works;
• Pile segments must be lifted onto the pile driver frame by lifting devices and must be anchored throughout the construction process.

2.13.2.8 When constructing sand wells and filter wells:

• The leveling layer must have sufficient capacity to bear the load of the construction equipment. When necessary, the foundation should be load-tested with a fully loaded excavator or dump truck;
• In cases where multiple pieces of equipment are working on the same surface, they should be spaced apart by a distance greater than the total height of the equipment.

2.13.3 Sinking Shafts

2.13.3.1 When adding additional loads to the shaft walls, the safety of people working below the shaft must be ensured. Excavation below the shaft rim must not exceed 1 m.

2.13.3.2 Means must be provided to ensure the safety of people entering and exiting the shaft. Measures must be in place for quick evacuation in case of sudden soil collapse. There must be 2 power sources for water drainage pumps in the shafts (one in use and one backup).

2.13.3.3 People must not be allowed under the shaft when the bucket is scooping soil out of the shaft. In cases where a signaler is required under the shaft, that person must stand outside the bucket’s operating range and must have protective covers above.

2.13.3.4 When using a crane to lift soil out of the shaft, the bucket must be placed in a mobile barrier pipe system and light signals must be used.

2.13.3.5 The shaft area where people are working below must have covers above and comply with the provisions in 2.1.

2.13.3.6 Trestles, scaffolds, supports, and connection components for grout pipes must be constructed in accordance with the provisions in 2.8 and 2.17.

2.14 Construction of Underground Structures

2.14.1 General Requirements

2.14.1.1 When constructing underground structures, in addition to implementing the provisions in this section, the current regulations on safety in mine tunnels must also be followed.

2.14.1.2 Before constructing underground structures, the following documents must be available: design, technical construction design, topographic maps, geological and hydrological data, diagrams of existing structures in the construction area, and acceptance documents for safety conditions.

2.14.1.3 When carrying out underground structure construction, there must be a technical construction method design including:

• Technical construction process guiding the construction sequence and safe support and installation measures;
• Measures to control groundwater;
• Measures to protect various pipelines, communication lines, other tunnels that have been or are being constructed, as well as other structures on the ground near the construction site;
• Plans for preventing and handling emergencies in underground structures;
• Measures for ventilation, lighting, monitoring of toxic gases, and ensuring environmental sanitation throughout the construction process.

2.14.1.4 When constructing underground structures under or near other structures, precautionary measures and close monitoring of the stability of those structures must be in place before and during construction.

2.14.1.5 People working in underground structures must be equipped with personal protective equipment in accordance with current regulations.

2.14.1.6 All machines, equipment, and vehicles serving the construction of underground structures, in addition to complying with the provisions in 2.6, must also comply with specific regulations suitable for safety conditions during the construction of underground structures.

2.14.1.7 A dedicated (or semi-dedicated) mine rescue team must be established, fully equipped with means to rescue people from poisoning, collapse, and fire, in order to provide timely rescue in case of unexpected incidents.

2.14.2 Safety during Construction

2.14.2.1 When entering to work in underground structures, there must be at least 2 people or more, and strict control of the number of people entering and exiting before and after each shift must be organized. At each shift change, the number of workers and the safety conditions of the workplace must be carefully checked and fully recorded in the shift handover log.

2.14.2.2 Before working, everyone must fully prepare the necessary materials and tools for a work shift. Supports from the tunnel portal to the tunnel face under construction must be checked, along with safety devices and technical safety conditions. All rocks in the work area must be cleared to ensure safety before construction can begin.

2.14.2.3 When signs of danger that may cause occupational accidents or incidents are detected, work must be stopped and promptly handled.

2.14.2.4 When there are changes in geological or hydrological conditions, the technical construction method design must be reviewed and revised accordingly.

2.14.2.5 Before constructing near underground power lines or pressurized pipelines, the power must be cut off or the pipeline valves must be locked.

2.14.2.6 When constructing underground beneath a railway line, the condition of the railway foundation must be regularly observed. If deformation of the railway foundation is observed, work must be immediately stopped and promptly handled.

2.14.2.7 During the construction of underground structures, if the generation or suspicion of methane, carbon dioxide, or other toxic gases arises, measurements must be taken to specifically determine the gas concentrations, and measures must be taken to reduce the concentrations to permissible regulated levels, while also implementing measures to prevent and combat poisoning and gas fires and explosions.

2.14.2.8 Drilling and blasting in underground structures must comply with QCVN 02: 2008/BCT.

2.14.2.9 When excavating tunnel faces, attention must be paid to observing the phenomenon of face collapse. If it occurs, work must be immediately stopped and promptly handled.

2.14.2.10 When there are deformations in support struts, additional new struts must be reinforced.

2.14.2.11 When support struts are found to be damaged, they may only be removed one at a time. Before removal, the struts in front of and behind the damaged strut must be securely reinforced. In dead-end tunnels, when replacing struts or expanding a compressed tunnel section, support must be carried out following the face, and people must not be allowed to enter and work inside (from the expanded section to the face). At junctions with a dead-end branch tunnel, when supporting at a distance of 5 m from the junction, all work in the dead-end branch must be immediately stopped. Repairs of tunnels with a slope above 25o must be done from top to bottom.

2.14.2.12 When excavating and supporting vertical shafts, attention should be paid to:

• In the range from the shaft face to the permanent support, there must be temporary supports. In cases of hard, stable rock, temporary supports must not be more than 1 m away from the shaft face;
• There must be a protective platform to block falling objects from above, with the platform no more than 4.0 m from the shaft bottom;
• The distance from the edge of the protective platform to the shaft support wall must not exceed 0.5 m;
• When moving the platform, workers at the face must all go up to the ground surface;
• Construction technical staff must supervise on-site the movement of the protective platform and other mechanical equipment suspended in the shaft;
• When using a suspended platform, a roof must be built above to protect the people working on the platform;
• Before blasting, the suspended platform must be pulled up to a distance of at least 15 m to 30 m from the face;
• If using a suspended bucket to transport soil and rock, the shaft opening gate must only be opened when the bucket passes through. The gate must be sealed.

2.14.2.13 When lining shafts with stone, brick, or concrete, the gap between the pit wall and the shaft wall must be tightly filled.

2.14.2.14 Around the shaft opening, there must be a fence with a minimum height of 2.5 m, with an iron gate at the entrance. When work is stopped, those gates must be carefully locked. All level openings in the shaft must also have iron gates or iron bar barriers.

2.14.2.15 Excavation of tunnels using a tunneling shield:

– Accessory mechanisms of the tunneling shield must be lowered into the construction position and installed under the direct supervision of construction technical staff and must follow unified commands;

– Soil excavation is only allowed within the limits of the shield’s overhanging roof;

– The tunneling shield must not be moved a distance greater than the length of the supported vault section.

2.14.2.16 Excavation of tunnels using the horizontal pipe jacking method:

– Workers are allowed to work inside the pipe when the inside diameter of the pipe is equal to or greater than 1.2 m;

– Pipes longer than 7 m must be forcibly ventilated with a clean air volume calculated for the respiration of one person not less than 4 m³/min;

– Soil excavation by manual methods inside the pipe is only allowed when gas and water have been eliminated from the face;

– Two-way communication must be provided with workers working inside the pipe;

– Soil excavation beyond the edge of the pipe is not allowed.

2.14.3 Movement and transportation in underground works

2.14.3.1 At each entrance and exit of an underground work, there must be rules regulating safe movement and transportation in the tunnel. In addition to the provisions in this Regulation, it is necessary to comply with current regulations on safety requirements in the exploitation of mining tunnels for ore and non-ore minerals. The reinforcing structures at the shaft mouth leading down to the underground work must be at least 0.5 m higher than the shaft mouth. The shaft door must have a sturdy cover, and no objects may be placed on the cover or around the shaft mouth within a radius of less than 0.5 m.

2.14.3.2 Intersections in underground works must have signs and arrows with specific instructions.

2.14.3.3 Tunnel sections that are no longer in use or temporarily not in use must be securely fenced off and marked with signs or red lights. Deep pits and trenches on surfaces with people passing through must be carefully covered or fenced off.

2.14.3.4 When passing through tunnels with winch transportation, the consent of the operator must be obtained. Passage is only allowed after the transport vehicle has exited the winch track and the barrier at the winch head has been closed.

2.14.3.5 Paths for ascending and descending underground works through vertical shafts or inclined shafts must have specific regulations and ladders arranged according to the tunnel’s inclination.

– Inclinations below 45° must have sturdy handrails;

– Inclinations above 45° must use cage ladders, ladders with protective railings, or elevators;

– In vertical shafts, the ladder inclination must not exceed 80°, and rest platforms must be provided every 8 m in height.

2.14.3.6 When moving on ladders, work tools such as hammers, pliers, etc., must be kept in securely attached bags.

2.14.3.7 In tunnels with transport vehicles, separate walkways must be provided with a width of:

– At least 0.7 m (measured from the outer edge of the vehicle to the outer edge of the support arch) for tunnels with trolley transportation;

– At least 1.5 m for tunnels with automobile transportation.

2.14.3.8 It is not allowed to pass between two closely parked vehicles, climb over a train of vehicles, or stand on the buffers of trolleys.

2.14.3.9 No vehicles are allowed to be transported in underground works without adequate lighting as prescribed.

2.14.3.10 Simultaneous transportation of people and other materials in the same elevator is not allowed. Transportation of people by skip cars or other self-unloading devices is not allowed.

2.14.3.11 Transportation by trolley tracks must follow the provisions in 2.4 and the following requirements:

– The inclination of trolley tracks must not exceed 7%;

– The speed of hand-pushed trolleys must not exceed 4.0 km/h;

– The speed of cable-pulled trolleys must not exceed 3.6 km/h;

– When pushing trolleys, lighting must be provided so that everyone can see;

– Standing in front to brake or pull trolleys is not allowed.

2.14.3.12 Winches used for pulling must be placed on a frame and securely linked. Signal communication must be provided when the winch is in operation. Movement and work along both sides of the winch cable are not allowed when the winch is in operation.

2.14.3.13 Cable hooks must not be detached until the train of vehicles has completely stopped. Heads must not be inserted between two rail cars to detach or connect them.

2.14.3.14 In addition to complying with the provisions in 2.4, transportation in underground works by automobile must also comply with the following provisions:

– Vehicle speed must not exceed 5 km/h;

– People are not allowed on the truck bed or outside the vehicle cab;

– Brakes, horns, headlights, signal lights, etc., of the vehicle must be adequate and function properly;

– Vehicles must not be parked for rest inside the tunnel;

– Gasoline-powered vehicles must not be used in underground works.

2.14.4 Use of electrical equipment and lighting

2.14.4.1 In addition to implementing the provisions in this section, the installation and use of electrical equipment in underground works must also comply with the provisions in 2.3 and current regulations on safety grounding and bonding of electrical equipment.

2.14.4.2 Electrical equipment must have automatic relays that disconnect in case of failure. The insulation condition of parts prone to current leakage and the operation of leakage relays must be periodically checked.

2.14.4.3 There must be an electrical network diagram clearly indicating the power network, lighting network, locations and capacities of electrical equipment, distribution devices, signaling devices, and telephones. When there are changes, those changes must be clearly recorded in the diagram.

2.14.4.4 Underground works with hazards of vapors, gases, dust, or explosions must use appropriate explosion-proof safety electrical equipment.

2.14.4.5 Electrical switches and circuit breakers must be placed in convenient and safe locations for use. Each device must have a clear instruction label.

2.14.4.6 Spotlights used in underground works must be installed with frosted glass.

2.14.4.7 Walkways and stairs for ascending and descending must be regularly illuminated.

2.14.4.8 Electrical stations in underground works must have adequate and appropriate firefighting equipment.

2.14.4.9 Electrical cables in underground works:

– Must use cables with rubber insulation sheathing and outer protective metal sheathing if they are fixed cables;

– If they are mobile cables, flexible cables with rubber insulation sheathing must be used;

– Electrical cables must be suspended high to avoid damaging impacts.

2.14.4.10 Lighting in underground works must only use power lines with a voltage not exceeding 127 V. If fixed fluorescent lamps are used, power lines with a voltage not exceeding 220 V are allowed.

2.14.4.11 Control circuits used for fixed and mobile machines are allowed to use a voltage not exceeding 36 V if insulated sheathed wires are used and 12 V if bare wires are used. In underground works without methane gas or explosive dust hazards, a voltage of 24 V is allowed on bare wires.

2.14.4.12 Open control transformers must not be used in underground works.

2.14.5 Ventilation

2.14.5.1 Underground works must ensure ventilation using appropriate ventilation equipment. Single-entry tunnels deeper than 10 m must be forcibly ventilated.

2.14.5.2 Ventilation in underground works must always ensure:

– The oxygen content in the air is not less than 20% by volume;

– The content of other harmful gases is below the permissible limit;

– The amount of air needed for the respiration of one person is not less than 4 m³/min;

– The maximum temperature does not exceed 30°C.

2.14.5.3 The power supply for the main ventilation fan must be provided from two independent sources (one operating source and one backup source).

2.14.5.4 The main ventilation fan:

– Must have a mechanism to reverse the air direction within 10 minutes in case of failure and ensure 60% of the air volume compared to the standard air volume during normal operation;

– Must have a backup motor, and if methane gas is present, a backup fan must also be provided.

2.14.5.5 If there is a possibility of toxic gases or methane gas, workers must be fully equipped with protective equipment and tools in accordance with prescribed regulations and other testing devices.

2.14.5.6 If a large amount of toxic gas appears or the ventilation system fails during work, work must be immediately stopped, and everyone must evacuate to a safe location. Work can only be resumed after the situation has been handled and safety is ensured.

2.14.5.7 Rock drilling must be carried out with wet drilling or other dust control measures.

2.14.5.8 Welding in underground works requires specific ventilation calculations to ensure that the concentration of toxic fumes is below the permissible level.

2.14.5.9 The entrance to underground works must be regularly cleared of waste and excess materials, as well as unused support structures, scaffolding, and equipment.

2.14.5.10 The drainage system in underground works must be regularly maintained to ensure good water drainage.

2.15 Production of mortar and concrete

2.15.1 General requirements

2.15.1.1 When working in warehouses storing materials prone to dust generation (cement, lime, gypsum, etc.) and at locations with crushing machines, grinding machines, and screening machines for raw materials and semi-finished products, requirements for ventilation and dust control must be met.

2.15.1.2 Screw conveyors must have protective wire mesh covers. When transporting dusty materials, they must have tight-fitting covers.

2.15.2 Lime pits and lime slaking

2.15.2.1 When slaking lime, lime lumps must not be submerged more than 1/3 of the height of the slaking pit or tank. A safety fence must be installed around the lime slaking pit; warning signs must be posted; in areas with people passing through at night, signal lights must be provided. The fence must be 50 cm away from the pit mouth, at least 80 cm high, and have two horizontal bars capable of preventing people from falling. Fence posts must be deeply and securely buried.

2.15.2.2 Lime pits must not be made near roads with heavy foot or vehicle traffic.

2.15.2.3 When removing lime from the pit, specialized tools must be used. Lime must not be removed directly by hand; entering the lime pit is not allowed.

2.15.3 Mixing mortar and concrete

2.15.3.1 When the mixing drum is in operation or under repair, the hopper must be lowered to a safe position.

2.15.3.2 Shovels or other hand tools must not be used to remove mortar and concrete from the mixing drum while it is in operation.

2.15.3.3 When using additives in the mortar mixture, measures must be taken to prevent burns and injuries, and the manufacturer’s regulations (or instructions) must be followed.

2.15.4 Transportation of mortar and concrete

2.15.4.1 When transporting mortar and concrete using hand carts, cranes, or lifting machines, the provisions in 2.4 and 2.6 must be strictly followed.

2.15.4.2 Working bridges for concrete-carrying trucks to pour into foundation pits must have a barrier at the end. The speed of trucks running on the bridge must be less than or equal to 3 km/h. Both sides of the working bridge must have walkways at least 1.2 m wide, and the outer side must have railings 1 m high.

2.15.4.3 Mortar and concrete must be released slowly only after the hopper has completely stopped. The distance from the bottom of the hopper to the surface of the structure where pouring is needed or the working platform must not exceed 1 m. If it exceeds 1 m, a chute or concrete pouring pipe must be used.

2.15.4.4 When using mortar pumps, the provisions in 2.6 must be followed.

2.15.4.5 Buckets or hoppers must not be used to transport mortar or concrete if their lids do not close tightly or their hanging and hooking components are not secure.

2.15.4.6 When using cranes to transfer buckets or hoppers containing mortar or concrete, the provisions in 2.6 must be followed, and workers must stand far away from the hazardous area of the load.

2.16 Masonry work

2.16.1 Foundation masonry

2.16.1.1 The condition of the foundation pit walls must be regularly supervised and inspected. During the rainy season, attention must be paid to slope slippage or damage to the retaining walls.

2.16.1.2 Workers ascending and descending foundation pits must use leaning ladders or steps. When it rains, measures must be taken to prevent slipping and falling.

2.16.1.3 Materials must be lowered into foundation pits using mechanical methods or improved tools such as chutes, troughs with inclined planes, or buckets. Materials contained in buckets must be at least 0.1 m lower than the bucket rim. Standing close to the foundation pit mouth to pour materials into the pit is not allowed.

2.16.1.4 People must not be allowed to work or transport materials at the foundation pit mouth when there are people working below in the pit, unless safety measures are in place.

2.16.1.5 During construction, if the foundation pit is flooded with water, the water must be completely pumped out before work can continue. People must not stay in the foundation pit during rest breaks.

2.16.1.6 When constructing foundation pits deeper than 2 m or building foundations at the foot of hills or mountains during heavy rain, work must be immediately stopped.

2.16.2 Wall construction

2.16.2.1 The condition of the foundation or the previously built wall section, as well as the condition of the scaffolding and supports, must be examined before construction.

2.16.2.2 When building walls up to a height of 1.5 m from the ground or floor level, scaffolding or supports must be installed according to the provisions in 2.8.

2.16.2.3 Transporting materials to working platforms at heights above 2 m must be done using lifting devices. Brick lifting tables must have barriers to ensure that bricks do not fall or spill during lifting.

2.16.2.4 When making working platforms inside a building for wall construction, a fence or warning sign must be placed outside the building, 1.5 m away from the wall base if building at a height not exceeding 7 m, or 2 m away from the wall base if building at a height exceeding 7 m.

2.16.2.5 It is not allowed to: Stand on the wall edge to build; Walk on the wall edge; Stand on eaves to build; Lean ladders against newly built walls for ascending and descending; Place tools or building materials on the wall edge being built.

2.16.2.6 Walls must not be built more than two stories when the lower story does not yet have floor beams or temporary flooring.

2.16.2.7 When building walls, if there is heavy rain, thunderstorms, or winds of level 6 or higher, the masonry must be covered and supported to avoid erosion or collapse.

2.16.2.8 When building independent columns or gable walls, a roof cover must be immediately installed during the rainy season.

2.16.2.9 When building and simultaneously fixing cladding panels, construction should only be stopped when the masonry has exceeded the height of the upper edge of those cladding panels.

2.16.2.10 Building eaves that protrude more than 20 cm from the wall requires cantilever supports. The width of the cantilever supports must be 30 cm larger than the width of the eaves. Cantilever supports can only be removed when the eaves structure has reached its design strength.

2.16.2.11 Building door arches or thin shells requires a separate technical construction design. Removing arch formwork must comply with the provisions in 2.19.

2.16.2.12 Stone masonry processing must be carried out in a designated fenced area. Unauthorized personnel are not allowed to enter this area. If the distance between the working positions of stone masons is less than 3 m, protective partitions must be installed between those positions.

2.16.3 Chimney construction

2.16.3.1 At the area where a chimney is being constructed, within a radius of 10 m from the base of the chimney in all directions, fences and warning signs must be installed. The entrance and exit to this area must have a roof cover and warning signs.

2.16.3.2 When extending the support shafts of lifting machines, it must be based on the level of chimney body construction. The use of lifting machines in chimney construction must comply with the provisions in 2.6.

2.16.3.3 When workers ascend and descend, they must use scaffolding, ladders of the construction equipment, or iron ladders embedded at least 25 cm into the chimney body, or use other specialized devices. Lifting tables must not be used to transport workers up and down.

2.16.3.4 Around the chimney body from a height of 3 m, protective flooring or netting 2 to 3 m wide must be installed. If wooden planks are used for protective flooring, the wood must be at least 4 cm thick. If protective netting is used, it must be woven with 3 mm diameter steel wire with a mesh size of 20 x 20 mm. The flooring (or netting) must be inclined towards the chimney body at a minimum angle of 15°.

2.16.3.5 When using electric lighting inside the chimney body, safety regulations for electrical use must be followed.

2.16.3.6 At the work location, on the working platform, as well as on the protective shields, excess materials and debris must be regularly cleaned up.

2.16.4 Furnace construction

2.16.4.1 When building furnaces, suspended scaffolding or suspended frame scaffolding specified in 2.8 must be used. The scaffolding must be erected at a minimum distance of 5 cm from the masonry.

2.16.4.2 When bringing materials to working platforms at heights greater than 2 m, lifting machines placed outside the masonry must be used. Workers on the working platform responsible for loading and unloading at the lifting table and workers operating the lifting machine below must communicate with each other using sound or light signals.

2.16.4.3 When working in locations where harmful gases may be generated (near blast furnaces, scrubbing towers, etc.), there must be personnel on standby for emergency rescue in case of sudden accidents. Valves, locks, and regulating doors of gas pipelines must not be opened without authorization. Prohibition signs must be posted on the above-mentioned components.

2.16.4.4 Using brick grinding machines must follow the provisions in 2.6.

2.16.4.5 Lighting at narrow and dark construction locations must follow the provisions in 2.15.2.2.

2.16.4.6 When working on furnace gas pipelines or gas filtering components, there must be measures for prompt response in case of sudden accidents. When working near furnace gas pipelines, all doors on one side must be closed to avoid drafts.

2.17 Formwork, reinforcement, and concrete work

2.17.1 Fabrication and installation of formwork

2.17.1.1 Formwork used to support concrete structures must be fabricated and installed in accordance with the requirements in the approved construction method design.

2.17.1.2 Formwork for the upper floor can only be placed after the formwork for the lower floor has been secured.

2.17.1.3 For installing formwork at heights not exceeding 6 m, support stands can be used for operation; at heights above 6 m, working platforms must be used. Installing suspended formwork or self-supporting formwork at heights above 8 m must be assigned to experienced workers.

2.17.1.4 Installing formwork for vault and thin shell structures requires working platforms and protective railings. The distance from the formwork to the working platform must not exceed 1.5 m. At inclined formwork positions, the working platform must be made in steps with a width of at least 40 cm.

2.17.1.5 Suspended formwork must be securely connected. Suspended formwork can only be placed on the frame after the frame components have been securely connected.

2.17.1.6 Equipment, materials (not included in the design), and people not directly involved in concrete pouring must not be allowed to stand on the formwork.

2.17.1.7 Formwork panels and formwork components must not be placed or stacked on staircase landings, balconies, sloping surfaces, walkways near openings or outer edges of the structure, in vertical or inclined positions when they are not braced.

2.17.1.8 Before pouring concrete, the formwork must be inspected; if there is any damage, it must be repaired immediately. The repair area must have fences and warning signs.

2.17.2 Large-panel formwork

2.17.2.1 Climbing up and down formwork stacks with a height greater than 1.5 m must be done using specialized ladders.

2.17.2.2 When using large-panel formwork together with lifting equipment, the lifting equipment must have audible signal devices.

2.17.2.3 Large-panel formwork components, specialized cantilevers, scaffolding working platforms, etc., can only be used after being inspected by construction technical staff.

2.17.2.4 Simultaneously lifting and moving two or more components of large-panel formwork by crane is not allowed, except in cases where pre-assembled components are permitted in the design.

2.17.2.5 Openings for installing staircase panels and landings must be fenced with railings.

2.17.2.6 Lifting and moving wall panels of large-panel formwork with a surface area less than or equal to 12 m² is not allowed when the wind speed is 10 m/s, and for panels with an area greater than 12 m² when the wind speed is 7.5 m/s.

2.17.2.7 During the assembly of large-panel formwork components, unauthorized personnel are not allowed to enter the hazardous area of the load during lifting, moving, and lowering of the formwork.

2.17.2.8 Walking and working on the assembled wall panels of large-panel formwork is not allowed when they do not have working platforms and protective railings.

2.17.3 Sliding formwork, climbing formwork

2.17.3.1 The construction area using sliding formwork or climbing formwork must have fences and warning signs.

2.17.3.2 The assembly of sliding formwork, climbing formwork, and suspended scaffolding components must follow the design and provisions in 2.8.

2.17.3.3 When moving sliding formwork or climbing formwork, the fastening devices (for reciprocating sliding) and lifting devices (for continuous sliding) must be checked.

2.17.3.4 Workers working at heights and workers working below must communicate with each other using sound or light signals.

2.17.3.5 The maximum allowable load must be marked on the working platform, and materials can only be stacked on the working platform at predetermined locations specified in the design.

2.17.3.6 Sliding formwork components must be stored in dry, flat, and covered storage yards.

2.17.3.7 Lifting devices and equipment used for sliding formwork construction must have an audible signaling system and can only slide after being inspected and receiving orders from the construction technical staff in charge.

2.17.3.8 During sliding, unauthorized personnel are not allowed to climb onto the working platform. Workers must not gather on the working platforms of the sliding formwork. Passage is only allowed for one person at a time. To move between the working platform of the outer ring formwork and the working platform on the sliding formwork, a crossing bridge with a width of not less than 0.8 m must be used. Moving between the two platforms must be done through a dedicated opening using a special ladder. After ascending or descending, the opening must be covered.

2.17.3.9 When constructing hollow bridge piers using sliding formwork, the openings on the horizontal reinforcement platforms for workers to ascend and descend must be staggered; if arranged on the same vertical axis, they must have covers.

Translating the provided content from Vietnamese to English, maintaining the original formatting and using appropriate technical terminology for the construction industry:

2.17.4 Reinforcement Processing and Installation

2.17.4.1 Preparation of blanks and processing of reinforcement must be carried out in a separate area, with fences and warning signs around.

2.17.4.2 Cutting, bending, and pulling reinforcement must use machines or specialized equipment. Use of reinforcement processing machines must comply with the provisions in 2.10. Measures must be taken to prevent steel from flying when cutting reinforcement.

2.17.4.3 Reinforcement processing tables must be securely fixed, especially when processing steel with diameters larger than 20 mm. If the reinforcement processing table has workers working on both sides, there must be a protective steel mesh in the middle at least 1 m high.

2.17.4.4 When straightening round coiled reinforcement with a machine, it is necessary to: Cover the safety shield on the coil shaft before starting the machine; Brake the motor when inserting the reinforcement end into the coil shaft; Fence off both sides of the steel wire running from the coil shaft to the machine drum.

2.17.4.5 The coil shaft of steel coils must be placed 1.5 m to 2 m from the machine drum and no higher than 0.5 m above the floor, with fences around. Between the coil shaft and the machine drum, there must be a device to limit the displacement of the steel wire being unwound. The steel wire may only be connected to the machine when the machine has stopped operating.

2.17.4.6 Straightening reinforcement with an electric winch or hand-cranked winch must have measures to prevent the steel wire from slipping and flying into people. The end of the winch cable is connected to the steel that needs straightening by specialized devices. Do not connect by tying. The cable and steel wire during pulling must be in a shielded groove. The reinforcement end may only be detached from or attached to the winch cable when the winch has stopped operating.

2.17.4.7 Transmission machines must not be used to cut steel segments shorter than 80 cm if there are no safety devices.

2.17.4.8 The position of bent reinforcement on the machine table may only be shifted when the rotating disc has stopped operating.

2.17.4.9 Do not straighten steel segments by stretching them at unguarded and unsafe locations on the construction site.

2.17.4.10 Do not use hand shears when cutting steel bars with lengths less than 30 cm.

2.17.4.11 Reinforcement cages must be carefully placed, not turned over or dropped, before installing formwork for them.

2.17.4.12 Installation of reinforcement for independent frames, beams, joists, columns, walls, and other similar structures must use working platforms with widths greater than or equal to 1 m.

2.17.4.13 Before transferring reinforcement mesh panels to the installation location, welds and ties must be checked. When cutting off excess steel parts at height, workers must wear safety harnesses and there must be warning signs below.

2.17.4.14 Walkways on reinforcement frames must have planks with widths not less than 40 cm.

2.17.4.15 Welding of reinforcement to frames and meshes, welding of starter bars, etc. must comply with the provisions in 2.9.

2.17.4.16 Reinforcement must not be stacked on work platforms or formwork in excess of the permissible load in the design.

2.17.4.17 When placing reinforcement near power lines, the power must be cut off. In cases where the power cannot be cut off, measures must be taken to prevent the reinforcement from touching the power lines.

2.17.5 Prestressed Reinforcement

2.17.5.1 Before starting to tension bars or bundles of reinforcement for prestressed concrete structures, the condition of the hydraulic jacks and other related equipment must be checked. The tensioned reinforcement bars must not have defects such as cuts, bends, twists, or breaks.

2.17.5.2 When tensioning reinforcement, there must be fences at least 1.5 m high at both ends of the tensioning bed and between the tensioning devices, except in cases where the reinforcement is placed in steel ducts. When tensioning reinforcement, there must be sound or red light signals.

2.17.6 Concreting and Vibration

2.17.6.1 Before concreting, the installation of formwork, reinforcement, scaffolding, working platforms, and transport routes must be checked.

2.17.6.2 When concreting structural parts with inclinations of 30o or more, there must be anchor ropes to securely tie the equipment. Workers must wear safety harnesses.

2.17.6.3 When concreting in deep pits or tunnels, workers must stand on working platforms.

2.17.6.4 Using vibrators to compact concrete mortar requires: Grounding the vibrator casing; Using insulated wire to connect from the distribution board to the vibrator’s electric motor. Stopping the vibrator for 5 to 7 minutes after each continuous operation of 30 to 35 minutes. Machine operators must be equipped with insulated rubber boots and other personal protective equipment.

2.17.6.5 When concreting at depths greater than 1.5 m, chutes or trunks must be used, securely fixed to the formwork parts or working platforms.

2.17.6.6 Using vibrating trunks to pour concrete mortar requires: Securely fixing the shaking machine to the trunk; Not standing under the trunk when pouring concrete.

2.17.6.7 Passageways below the area where concrete is being poured must have fences and prohibition signs. In cases where people must pass through, there must be cover plates above those passageways.

2.17.6.8 People not assigned to the task are not allowed to stand on the concrete pouring platform. Workers assigned to guide, adjust, and unhook the concrete bucket must have gloves and boots.

2.17.7 Concrete Curing

2.17.7.1 When curing concrete, scaffolding or supports must be used. Do not stand on supporting columns or the edges of formwork. Do not use ladders leaning against concrete structural parts being cured.

2.17.7.2 Curing concrete at night or on obscured structural parts must have illumination.

2.17.8 Formwork Removal

2.17.8.1 Formwork may only be removed when the concrete has reached the specified strength.

2.17.8.2 When removing formwork, it must follow a reasonable sequence, and measures must be taken to prevent the formwork or the structure from collapsing unexpectedly. The formwork removal area must have fences and warning signs.

2.17.8.3 Before removing formwork, all excess materials and equipment placed on the structural parts about to have formwork removed must be cleaned up.

2.17.8.4 When removing formwork, the condition of the structural parts must be regularly observed. If deformation is observed, removal must be stopped and the construction technical staff must be immediately notified.

2.17.8.5 After removing formwork, openings in the structure must be covered. Removed formwork must not be left on the work platform or thrown from a height. After removal, formwork must have nails removed, be maintained or repaired and reinforced, and stored in a designated location.

2.17.8.6 Removal of formwork for large-span reinforced concrete compartments must fully implement the requirements stated in the design regarding temporary support.

2.18 Assembly Works

2.18.1 General Requirements

2.18.1.1 Use of cranes and other equipment in the assembly of structural components must comply with the provisions in 2.6 and the current regulations on safety techniques for lifting equipment.

2.18.1.2 Use of electric tools, compressed air or cutting gas, drilling, welding, etc. during high-altitude assembly must have scaffolding in accordance with the provisions in 2.8.

2.18.1.3 Ladders must not be leaned against components being assembled for any work.

2.18.1.4 During assembly, scaffolding or supports specified in the construction design must be used. In cases where the design provisions are deviated from, permission must be obtained from the construction technical staff in charge.

2.18.1.5 Structures and components must be arranged reasonably to ensure ease of hook tying and to prevent collapse or sliding during loading and unloading.

2.18.1.6 Specialized lifting eyes for hooking structures and components must be secure and must not break or deform during lifting.

2.18.1.7 Structures and components without specialized hooking parts must have their positions and hanging methods calculated and determined to ensure that they do not slip or fall during the entire lifting and moving process.

2.18.1.8 Structures and components that may overturn during lifting and moving must be securely lashed and soft ropes must be used for restraint.

2.18.1.9 For structures and components that may deform during crane assembly, generating secondary stresses, they must be securely reinforced before being lifted.

2.18.1.10 Crane assembly must be stopped in winds of level 5 or higher, or when it is dark.

2.18.1.11 During crane assembly, people must not be allowed to stand or cling onto structures or components. At the same time, structures and components must not be allowed to pass over people’s heads.

2.18.1.12 After hook tying, the load must be lifted to a height of 20 cm, then stopped to check the balance and stability of the load. If the suspended load is not balanced, it must be lowered to the ground for adjustment. Load adjustment is not allowed when the load is in a suspended state.

2.18.1.13 The person receiving the lifted object at height must stand on the working platform of the scaffolding or support and must wear a safety harness. The safety harness must be hooked to stable structural parts of the construction or to a truss wire that has been stretched and securely fixed to stable structural parts of the construction.

2.18.1.14 Do not stand on assembled structures or components that have not been securely stabilized. Do not reach out to catch, pull, or rotate the lifted object while it is still suspended.

2.18.1.15 The lifting hook may only be detached from the structure or component after they have been anchored according to the design requirements (permanently or temporarily fixed). Do not displace installed structures or components after detaching the lifting hook, except in cases where the construction design has specified.

2.18.1.16 Work must not be stopped when structures or components have not been installed in a stable position.

2.18.1.17 Lifted objects must not be stacked or temporarily placed on floor slabs, working platforms, or other structural parts in excess of the design load-bearing capacity of those structures.

2.18.1.18 Upper parts may only be installed after the lower parts have been fixed according to the design requirements.

2.18.1.19 When it is necessary to have people working below equipment or structures being assembled (including above them), special measures must be taken to ensure the safety of the workers.

2.18.1.20 When crane assembling near operating power lines, safe distances must be maintained in accordance with the provisions in 2.6.

2.18.2 Assembly of Precast Concrete Components

2.18.2.1 When installing columns, guide frames must be used. In cases where there are none, columns must be fixed by lashing wires and wedges. Welding and concreting works to connect positioned reinforced concrete structures must be carried out from working platforms or specialized mobile scaffolding with guardrails, or from suspended platforms.

2.18.2.2 Floor slabs or roof slabs may only be installed after the beams or trusses have been securely fixed and safe working platforms have been built.

2.18.2.3 Walls and upper floor slabs may only be installed after the lower floor slabs have been completely installed. Openings on floor slabs must be securely covered or fenced; appropriate warning signs must be provided.

2.18.2.4 Stair flights and landings must be assembled simultaneously with the assembly of the building or structure.

2.18.2.5 After installing stair flights, if the permanent handrails have not yet been installed, temporary handrails must be made for workers to safely go up and down. Each landing must be installed together with the stair flights before installing the next level.

2.18.2.6 When installing wall panels, sufficient anchor wires or braces specified in the design must be provided.

2.18.2.7 When installing balcony slabs or cantilever slabs, braces must be provided before permanent fixing. When fixing balcony slabs or cantilever slabs and installing balcony railings, workers must wear safety harnesses.

2.18.3 Installation of Steel Structures

2.18.3.1 Large steel structures must be reinforced with temporary bracing devices to ensure stability during crane installation.

2.18.3.2 Walkways from one truss to another must be boarded and have protective handrails. Walking on wind bracing, diagonal members, or purlins and on the upper chords of trusses is prohibited. Walking on the lower chord of a truss is only allowed when there is a cable stretched along the truss for attaching a safety harness. Walkways on the roof or upper chord of a steel truss must be at least 0.5 m wide and have a 1.0 m high protective handrail.

2.18.3.3 Before lifting a steel structure, the hook attachment points must be thoroughly checked and the cables must be evenly tensioned. Attaching hooks to bracing members or gusset plates is prohibited.

2.18.3.4 Installing skylights together with trusses is prohibited. When installing skylights, workers must stand on a working platform and wear safety harnesses. The installation work must follow the design-specified sequence.

2.18.3.5 Crane hooks may only be detached from an installed structure after ensuring the connections meet the following requirements:

• For columns, there must be at least 4 anchor bolts on each side or it must be secured by a guiding frame and tie rods;
• For trusses, after installing all purlins and bracing members with the previously installed and fixed trusses;
• For crane beams, after tightening at least 50% of the bolts or rivets specified in the design;
• For welded structures, temporarily bolt all bolt holes. If there are no bolt holes, specialized jigs must be used for tightening;
• For thin plate riveted structures, after bolting at least 20% of the holes along the perimeter;
• For ducts, after installing all joint bolts or welding 20% of the weld length specified in the design;
• For roof structures, it must be implemented according to the provisions in 2.8.

2.18.3.6 Assembling structures such as tanks and steam pipes at heights of 2 m or more must have working platforms.

2.18.3.7 The erection of steel structures may only be carried out when the concrete foundations and pedestals have attained the necessary strength to bear the load of the steel structure.

2.19 Working at Heights and on Roofs

2.19.1 General Requirements

2.19.1.1 At high positions of the structure or steeply sloped roofs, measures must be taken to ensure the safety of personnel, tools and materials in accordance with current regulations.

2.19.1.2 When working in high areas including rooftops with a height of more than 2 m, protective measures must be taken around the open edges with guardrails as prescribed. In places where safety rails cannot be used, other protective safety measures must be implemented.

2.19.1.3 When working at heights, the use of stairs, ramps or leaning ladders must comply with current regulations.

2.19.1.4 When working at heights and on roofs, if safety solutions using guardrails cannot be used, workers must be protected by safety nets or safety harnesses.

2.19.2 Roofing Work

2.19.2.1 The condition of the roof’s load-bearing structures and safety equipment must be thoroughly checked to ensure safety before performing work on the roof.

2.19.2.2 When working on roofs with a slope greater than 25°, workers must wear safety harnesses and attach them to a fixed point.

2.19.2.3 Workers operating on roofs with a slope greater than 25° must have a folding ladder placed across the ridge for safe access. The ladder must be securely fixed to the structure, have a width of not less than 30 cm, and have evenly spaced rungs at 40 cm intervals.

2.19.2.4 Materials may only be placed on the roof at positions specified in the technical construction design. Large roof panels must be transferred to the roof one at a time and immediately placed into position and temporarily fixed according to design requirements. In case multiple panels need to be transferred to the roof at once, specialized equipment must be used and the placement locations on the roof must be arranged to ensure safety.

2.19.2.5 When placing materials and tools on the roof, measures must be taken to prevent them from rolling or sliding down the sloped roof, including in case of wind impact.

2.19.2.6 Installing eaves, gutters, chimneys, roof parapets, skylights, roof edges, vents, drainpipes, etc. must have scaffolding or supports as specified in 2.8.

2.19.2.7 Within the area where people are working at heights and on roofs, barriers and warning signs must be placed below to prevent materials and tools from falling onto passersby. The barriers must extend 2 m beyond the roof edge projection when the roof height does not exceed 7 m, and 3 m when the roof height is greater than 7 m. In special cases, follow the construction design specifications.

2.19.2.8 Roofing work using bitumen must comply with the provisions in 2.11.

2.19.2.9 Work at heights and on roofs may only be stopped after securing all roofing sheets and cleaning up all materials and tools.

2.19.2.10 Roofing and work at heights must not be carried out when the weather is wet or rainy.

2.19.2.11 Openings on the roof must be covered and securely fixed.

2.19.3 Working on Chimneys

2.19.3.1 When installing and repairing chimneys at heights, suitable scaffolding must be used. Safety nets must be placed under the scaffolding at an appropriate distance.

2.19.3.2 The scaffold platform must be placed at least 65 cm from the top of the chimney.

2.19.3.3 A scaffold platform must be left just below the working platform to ensure safety during construction.

2.19.3.4 The distance between the inner edge of the scaffold and the outer wall of the chimney must not exceed 20 cm at any point.

2.19.3.5 Protective platforms must be placed at: chimney entrance; walkways and work areas to protect against falling objects.

2.19.3.6 When workers use an external ladder to climb the chimney, safety harnesses must be used as prescribed.

2.19.3.7 When working on independent chimneys, protective barriers must be placed at a safe distance.

2.19.3.8 Workers constructing, repairing, or maintaining chimneys are prohibited from: working outside the chimney without a safety harness; placing tools between protective clothing and their body or in non-specialized pockets; manually pulling heavy materials and equipment; anchoring pulleys or scaffolding to the climbing ladder without checking their stability; working alone; climbing the chimney without using a ladder or safety harness.

2.20 Finishing Works

2.20.1 General Requirements

2.20.1.1 Stacking, storing, loading, unloading and transporting materials using machinery, working platforms, scaffolding, ladders for finishing works such as plastering, painting, carpentry, glazing, tiling, etc. must strictly comply with the provisions in 2.4, 2.6 and 2.8.

2.20.1.2 Using ladders for finishing works at heights is prohibited, except for work in enclosed rooms with a height not exceeding 3.5 m.

2.20.1.3 Performing finishing works simultaneously on two or more floors along the same vertical line is prohibited if there is no protective covering platform between the floors.

2.20.1.4 Complete power disconnection must be ensured before plastering, painting, wallpapering or cladding surfaces of the electrical system. Lighting for the above finishing works (if any) must use a voltage not exceeding 36 V.

2.20.2 Plastering

2.20.2.1 Plastering inside and outside of buildings as well as other structural details must use scaffolding and supports as specified in 2.8.

2.20.2.2 When lifting mortar to a working platform height not exceeding 5 m, small mechanical equipment or improved tools must be used. For working platforms higher than 5 m, hoists or other lifting means must be used. Manually lifting mortar buckets to working platforms higher than 2 m is prohibited.

2.20.2.3 Buckets, pails containing mortar as well as other tools must be placed in secure positions to prevent them from falling, slipping, or spilling.

2.20.2.4 Machine plastering must comply with the provisions in 2.6. Workers operating plastering machines must wear boots, gloves and protective goggles.

2.20.2.5 Electricity used for plastering in tanks and confined spaces must have a voltage not exceeding 36 V.

2.20.2.6 When mixing mortar with chemicals, the manufacturer’s usage instructions must be followed. Areas for mixing mortar containing chlorine must be arranged in well-ventilated places and at least 0.5 km away from populated areas (if the above requirement cannot be met, an approved safety solution must be in place). Plastering with chlorine-mixed mortar in unventilated rooms, basements, or trenches is prohibited. Workers in contact with chlorine-mixed mortar must be fully equipped with personal protective equipment in accordance with current regulations.

2.20.3 Whitewashing, Painting

2.20.3.1 Whitewashing, painting and decorating the exterior of buildings must use scaffolding as specified in 2.8.

2.20.3.2 Painting skylight frames must use specialized scaffolding and workers must wear safety harnesses. Walking on the skylight frames is prohibited.

2.20.3.3 Leaning ladders may only be used for whitewashing and painting small areas at a height not exceeding 5 m from the floor or platform. At heights above 5 m, if using leaning ladders, the top of the ladder must be fixed to stable structural components of the building. Leaning ladders against window frames is prohibited.

2.20.3.4 Using whitewashing and oil painting machines must comply with the provisions in 2.6.

2.20.3.5 When painting indoors or using paints containing harmful substances, workers must be equipped with gas masks.

2.20.3.6 When painting indoors with paints containing harmful substances, all doors and ventilation devices in the room must be opened at least 1 hour before starting work.

2.20.3.7 Smoking and performing any work using fire or generating sparks is prohibited in areas using nitro paint. Power must be disconnected if there are live electrical wires or operating electrical equipment in the room.

2.20.3.8 Allowing people to enter rooms that have been whitewashed or painted with mixtures containing toxic substances that are not yet dry and not well ventilated without protective equipment is prohibited.

2.20.3.9 Paint preparation rooms must be well ventilated. Lighting and equipment in paint preparation rooms must ensure fire and explosion safety. Paint containers must have labels clearly stating the material name, code, solvent type, product number, production date and weight.

2.20.3.10 When using oil for preparation, measures must be taken to prevent oil from splashing out. Do not fill the cooking pot with more than 1/4 of its capacity. The oil heating area must be separately arranged and must comply with current fire prevention and firefighting regulations.

2.20.3.11 When removing old paint layers with chemicals, workers must wear rubber gloves and use a long-handled scoop. Waste solution after paint removal must be collected into a separate container for treatment in accordance with current environmental protection regulations.

2.20.4 Gluing Polyisobutylene and Other Waterproofing Materials

2.20.4.1 Rooms for washing, removing polyisobutylene and preparing adhesive paste must be separated from other production rooms; must have ventilation, lighting and explosion-proof measures.

2.20.4.2 Using ethylene gasoline to clean surfaces is prohibited. Ethylene gasoline storage in the workshop must not exceed the amount used for one day.

2.20.4.3 Containers for gasoline and adhesive paste must be sealed and placed in steel or wood drums with secure straps, locks, and rubber-lined edges.

2.20.4.4 When transferring adhesive paste or gasoline, aluminum, plastic or galvanized cans with tight lids must be used. When scooping adhesive paste, an aluminum scoop with a handle must be used.

2.20.4.5 When gluing polyisobutylene to outdoor equipment, the equipment must be grounded for protection; there must be a ventilation system, explosion-proofing, and a handheld electric light with a voltage not exceeding 12 V must be used.

2.20.4.6 Performing any work that may generate sparks within a radius of 25 m from the polyisobutylene gluing area is prohibited.

2.20.4.7 When someone is gluing polyisobutylene inside equipment, there must be a person on standby outside. The area where polyisobutylene is being glued must have barriers and warning signs.

2.20.4.8 For other waterproofing materials, the manufacturer’s usage instructions must be followed.

2.20.5 Use of sulfur cement and as-de-mit paint

2.20.5.1 The sulfur cement cooking kettle must be arranged at least 25 m away from the construction area. If the cooking kettle is placed indoors, an exhaust hood must be installed above it. When placing the cooking kettle outdoors, it must have a roof.

2.20.5.2 To heat the materials in the cooking kettle evenly and prevent the sulfur from burning locally, a sand cushion must be used to separate the materials into layers.

2.20.5.3 Before putting sulfur cement into the cooking kettle, the kettle must be dried. It is not allowed to fill the sulfur cement more than 3/4 of the kettle’s capacity.

2.20.5.4 When pouring sulfur cement into the joints of the furnace lining layer, workers must use gas masks.

2.20.5.5 As-de-mit powder must be stored in a container with a tight-fitting lid and kept in a separate room.

2.20.5.6 When mixing as-de-mit powder, workers must use gas masks and rubber gloves.

2.20.6 Surface cladding

2.20.6.1 The stone processing area must have fences and prohibition signs.

2.20.6.2 Stone carving workers must sit at least 3 m apart from each other; if the above distance cannot be ensured, there must be a shield in between. Workers must not be arranged to sit and work facing each other. Stone cutting and carving workers must have protective glasses and masks.

2.20.6.3 When processing large and heavy stone blocks, they must be firmly supported and secured.

2.20.6.4 The stone cutting area must have a wooden floor and good drainage channels. The floor must always be kept clean and measures must be taken to prevent slipping.

2.20.6.5 Stone processing rooms with dust generation must be well ventilated and workers must wear protective masks.

2.20.6.6 When using hand-held electric tools to process stone, the provisions in 2.5 must be followed.

2.20.6.7 When arranging processed stone materials in warehouses and yards, the provisions in 2.2 must be followed.

2.20.6.8 When cladding stone pieces onto the surface of structures, they must be ensured to be firm. When cladding large-sized pieces, support measures must be taken. The cladding must be done in order from bottom to top.

2.20.7 Glass

2.20.7.1 When lifting, moving, and installing glass panes at heights, protective floor covers must be made for positions directly below, or fences and prohibition signs must be placed in that area.

2.20.7.2 Installing glass for skylights and fixed window frames at heights must use scaffolding work platforms.

2.20.7.3 Ladders must not be leaned against glass surfaces or window frames with installed glass.

2.20.7.4 When moving large glass panes, it must be carried out by at least two workers, using canvas gloves, ropes with rubber pads, or other specialized tools. During movement, the glass pane must be placed in a vertical orientation.

2.20.7.5 When decorating glass surfaces by sand blasting or using acid, workers must be equipped with protective glasses, gloves, etc. according to current regulations.

2.20.8 Carpentry

Installation of windows and balcony doors must be done from inside the room.

2.21 Installation of technological equipment and pipelines

2.21.1 General requirements

2.21.1.1 All work involving the use of electrical equipment and lifting equipment must comply with the provisions in 2.5 and 2.6 and current regulations on safety techniques for using lifting equipment.

2.21.1.2 Trenches and pits at equipment foundations and places where workers pass through must be covered tightly; appropriate warning signs must be provided.

2.21.1.3 When cleaning the protective layers on technological equipment and pipelines, non-toxic alkaline solutions must be used. Before lifting the equipment to a height, dirt, sand, and other impurities adhering to the equipment must be cleaned off.

2.21.1.4 When construction work must be carried out under equipment being installed, or equipment that is still temporarily supported by jacks or suspended on cables, it must be secured by placing supports under the equipment that have been calculated to withstand the load of the equipment.

2.21.1.5 Static balancing of turbine compressor rotors, pumps, etc. must be performed on supports firmly attached to solid bases. The lifting capacity of the base and support shafts must not be less than 1.5 times the rotor weight. These supports must be of equal height and have guards to prevent the rotor from rolling or drifting unexpectedly.

2.21.1.6 When assembling cylindrical equipment and tanks made of multiple segments, chocks must be used to prevent the equipment from rolling unexpectedly.

2.21.1.7 When assembling equipment and pipelines by extending or elevating them, they must be securely fixed and not left in a suspended state.

2.21.1.8 For vertically installed equipment, if the equipment frame is not stable enough, it must be secured correctly according to the construction method and have at least 3 guy wires. The wires can only be removed when the equipment has been securely fixed.

2.21.1.9 It is not allowed to assemble parts and joints of equipment and pipelines onto similar equipment or pipelines that are in operation.

2.21.1.10 Necessary measures must be taken to protect workers from the effects of electric current when installing equipment and pipelines near power transmission lines.

2.21.1.11 When conducting inspection, assembly, repair, or dismantling of equipment and pipelines in an environment with toxic vapors or gases, or equipment and pipelines that have contained toxic vapors or gases, safe construction measures must be taken; it must be ensured that the equipment or pipeline section has been cleaned of toxic substances.

2.21.1.12 Assembly of equipment and pipelines under conditions with fire and explosion hazards must ensure:

• Use of non-ferrous metal tools or copper-plated tools that do not have the ability to generate sparks. Warming up the machine (if necessary) is only allowed using hot water or steam;
• Oil-soaked rags must not be used to clean the equipment. Oil-stained rags must be collected and placed in an iron barrel, and taken out of the room when the work is finished;
• Throwing metal machine parts or objects that can generate sparks is not allowed;
• Wearing shoes with nailed soles or metal cleats is not allowed.

2.21.1.13 When assembling oxygen equipment, rags or wedges with oil or grease must not be used.

2.21.1.14 When dismantling equipment and pipelines, the stability of the remaining equipment clusters must be ensured. The stability of those equipment clusters must be regularly monitored. Dismantling can only begin after the equipment or pipeline section to be dismantled has been completely separated from external circuits and other junctions. The dismantled parts can only be lifted and lowered when it is ensured that they will not get caught.

2.21.2 Assembly of technological equipment

2.21.2.1 Assembly of lifting equipment must strictly comply with the provisions in 2.6 and other current regulations on safety techniques for lifting equipment.

2.21.2.2 Assembly of thermal power equipment must comply with current regulations on safety techniques for boilers.

2.21.2.3 Installation of technological equipment is only allowed when there are technical documents, assembly and operation instructions, and construction and safety measures available.

2.21.2.4 All measures must be taken to prevent electric motors from reactivating when installing technological equipment with electric drives.

2.21.3 Testing of technological equipment

2.21.3.1 Before testing (no-load and load testing), the following must be done:

• Disseminate to test participants the requirements, work sequence, and approved labor safety measures;
• Notify people working in areas near the test site of the start and end times of the test;
• Fence off or set up protective guard positions to prevent unauthorized persons from entering the test area;
• Re-check the connections between the equipment and the machine base, the insulation condition and grounding of the electrical part, and the equipment. Re-check the starting, braking, measuring, and protection systems;
• Ensure adequate lighting for work positions; Clean and remove foreign objects from the equipment; Check the signal system;
• If necessary, set up an emergency alarm system and a rescue team.

2.21.3.2 The pressure in the equipment to be tested must be increased slowly and evenly and must not exceed the specified level. The readings of the measuring instruments and the operation of the entire system of equipment under test must be regularly checked.

2.21.3.3 All pressurized pipes and fittings must be tested by the hydraulic method before connection.

2.21.3.4 Before running a full test of the equipment, the motor must be run without load and run in parts.

• The first test run of the equipment must be without load, and then a comprehensive inspection must be performed when the equipment has come to a complete stop;
• The equipment can only be run with load after it has been tested without load; the manufacturer’s instructions must be followed.

2.21.3.5 After stopping the mechanical test, during breaks, or when inspecting the moving parts of the equipment, the energy supply must be cut off.

2.21.3.6 When testing technological equipment, it is not allowed to:

• Let people stand in front of doors, lids, and flange connections of pressurized equipment;
• Remove protective guards;
• Start the equipment without the permission of the test commander and without prior notification to other participants;
• Open doors, lids, clean, and lubricate the equipment; Lean or rest against moving parts; Perform work above and below the equipment.

2.21.3.7 Repair of errors detected after testing can only be carried out after the equipment has been completely stopped and the power supply has been cut off.

2.21.4 Installation of pipelines

2.21.4.1 Installation of pipelines

2.21.4.1.1 Loading, unloading, and transporting pipelines must comply with the provisions in 2.4, pipes stacked on transport vehicles must be securely fixed and not allowed to shift in both directions.

2.21.4.1.2 Pipes transported to the construction route must be placed at least 1.5 m away from the edge of the trench. Welded pipe sections need to be placed on specialized supports or directly on the ground, with cushions to prevent rolling or slipping.

2.21.4.1.3 When processing pipes at the processing facility, the following conditions must be ensured:

• When repairing, processing pipes, or doing other preparatory work, the pipes must be firmly supported at both ends;
• The rotating part of the pipe welding jig must be equipped with reliable braking devices;
• Rotating pipes on the jig must use specialized wrenches. Do not stand on the pipeline to roll it;
• When cleaning pipe ends or removing welding rust and when bending pipes by thermal methods, workers must wear protective glasses;
• Long pipe sections must have supports. When needing to spray water to cool the pipes, a long-handled scoop must be used.

2.21.4.1.4 When installing pipelines on overhead bridges, there must be supports or ladders for workers to go up and down, and they must not go up and down using the structures of the overhead bridge.

2.21.4.1.5 When installing pipelines near operating power lines, if the longest pipe section can come into contact with the conductors, the power must be cut off.

2.21.4.1.6 Scaffolding, supports, as well as machines and equipment must not be anchored to the pipes.

2.21.4.1.7 Pipes must not be installed and welded in a suspended state if adequate safety devices are not arranged below the work area.

2.21.4.1.8 When welding, cleaning, and sealing pipeline joints, there must be a roof to protect from rain and sun. The welder’s work area must be shielded, not allowing sunlight to shine in when the air temperature is above 30oC and not allowing rain or cold wind to blow in.

2.21.4.1.9 When scraping and washing pipes, there must be support platforms. The number of platforms and the arrangement depend on the technical characteristics, pipe diameter, and scraping and washing machines.

2.21.4.1.10 When doing pipe painting work as well as work related to bitumen, gasoline, and mastic, the provisions in 2.11 and 2.20 must be followed.

2.21.4.1.11 Sheds used as places for washing pipes with chemical solutions must have a good ventilation system and be far from where people work, only authorized persons with full personal protective equipment are allowed to enter.

2.21.4.1.12 Pipe sections and pipe fittings can only be lowered into the trench after everyone has left that section of the trench. Sticks or crowbars must not be used to freely roll pipes into the trench. Trench wall support bars must not be used as pipe supports. If the soil collapses while lowering the pipe, the soil can only be cleared after the pipe has been firmly supported. The support beam must protrude at least 1 m beyond the edge of the trench.

2.21.4.1.13 Before starting to lower the pipe into the trench, it is necessary to check the equipment and tools to ensure sufficient quantity and quality in accordance with the construction method. Cables, ropes, pulleys, etc. must be load tested in advance. The strength of the rope must have a safety factor of 6 times.

2.21.4.1.14 Pipe laying machines moving along the pipeline route must travel outside the limit of the natural soil collapse prism, but must be at least 2 m away from the edge of the trench.

2.21.4.1.15 Pipe laying machines in trenches, if standing in a position with a slope greater than 10o (hillside, mound, ditch side, etc.), must have their stability checked.

2.21.4.1.16 When placing support beams and pads to roll or slide pipes, it must be ensured to be firm and keep the trench wall stable.

2.21.4.1.17 When working inside a well or tank, there must be a person on duty at the well opening or tank entrance.

2.21.4.1.18 Construction of underwater underground pipelines must be equipped with rescue equipment according to the provisions in 2.1.3. Underground routes crossing river areas with boat traffic must be equipped with signaling devices during construction.

2.21.4.1.19 Means of transportation used for construction on rivers must have radio, signal, or loudspeaker communication with the shore. Unauthorized persons are not allowed on these means of transportation.

2.21.4.1.20 Work on floating vehicles and for divers to go underwater is only allowed when the waves do not exceed level 3. Boats passing through the area where divers are working underwater must reduce speed and must stay at least 50 m away from the diving boat.

2.21.4.1.21 Before pulling pipes to lay on the river or lake bottom, the pipe-carrying railcar must be braked and firmly secured. The pipe-pulling winch must have a firmly anchored cable.

2.21.4.1.22 During pipe pulling, there must be signals; the command vehicle must ensure continuous communication between the work supervisor and the workers directly performing each separate task.

2.21.4.1.23 No floating vessel is allowed to pass through the area where pipes are being pulled.

2.21.4.1.24 When laying the second pipeline parallel to the first operating pipeline, the construction design must include measures to properly protect the operating pipeline.

2.21.4.1.25 Laying pipelines across traffic routes must have fences and warning signs; at night, there must be red warning lights.

2.21.4.1.26 Laying pipelines across railways, people must be arranged to promptly notify everyone when the train is about to arrive.

2.21.4.1.27 Placing insulation for pipelines in trenches using pipe laying machines to temporarily lift the entire continuous long pipeline, measures must be taken to prevent the pipeline from shifting to the sides.

2.21.4.1.28 It is not allowed to stand and move on overhead pipeline sections.

2.21.4.2 Installation of technological pipelines

2.21.4.2.1 Fixed connection devices (such as supports, consoles, reinforced concrete or metal structures, wall pillars, suspension frames, etc.) must be placed before starting to assemble technological pipelines.

2.21.4.2.2 When marking the positions for placing supports, consoles, suspension frames, as well as when assembling pipelines, scaffolding must be used and the provisions in 2.8 must be strictly followed.

2.21.4.2.3 When drilling holes in walls or floors for running pipes or fixing support points, workers must wear protective glasses. In necessary cases, there must be a protective shield around.

2.21.4.2.4 When assembling pipelines made of glass, ceramics, or Ferro-silica, measures must be taken to prevent breakage and injury to workers.

2.21.4.2.5 In an operating workshop, pipelines can only be dismantled after that pipeline has been completely disconnected from the operating machines and pipelines.

• Pipe sections and separate pipe assemblies can only be dismantled after the remaining pipe parts have been securely fixed.
• Pipelines at different heights in the same vertical direction must not be dismantled at the same time.

2.21.5 Pipeline testing

2.21.5.1 Hydrostatic testing of pipelines must ensure the following requirements:

• The pipeline connecting from the pump to the pipeline to be tested must also have undergone prior hydrostatic testing;
• At the sealing faces, lids, doors with lids, flange connections, etc. of the pipeline during the test period, appropriate signs and markings must be placed;
• Test participants must stand in safe positions, with shields to prevent lids from flying out when connections are destroyed;
• The pressure in the pipeline must not be increased while examining and detecting damage;
• Hydrostatic testing of multiple pipes placed on the same frame or overpass at the same time is only allowed when the above structures have been calculated to withstand the corresponding loads.

2.21.5.2 Compressed air testing of pipelines is only allowed if the hydrostatic testing method is not suitable.

2.21.5.3 Testing of pipelines with cast iron fittings (except forged cast iron fittings) using compressed air must only use a pressure not exceeding 400 kPa. Cast iron fittings must undergo preliminary hydrostatic testing to determine their strength beforehand.

2.21.5.4 Compressed air testing of pipelines must ensure the following requirements:

• The compressor, equipment, and measuring instruments used in the test must be placed at least 10 m away from the pipeline to be tested;
• The safety valves of the equipment must be calibrated to the corresponding pressure;
• Connecting and disconnecting the steam pipes from the compressor to the pipe section must only be done when the compressor has been stopped.

2.21.5.5 Compressed air must not be used to test pipelines in an operating workshop or pipelines located on the same support, overpass, or trench with other operating pipelines.

2.21.5.6 During hydrostatic and compressed air testing of load-bearing pipelines, it is not allowed to:

• Tighten the bolts of flange connections;
• Stand facing the sealed flanges of the test pipeline;
• Tap on the welds;
• Use unreliable pressure gauges;
• Allow people in the area of the test pipeline when air is being compressed.

2.21.5.7 Pipeline testing must be organized during the day. In case it must be carried out at night, lighting for the test pipe section must be ensured with an illuminance of not less than 50 lux.

2.21.5.8 Determination of the dangerous zone when testing pipelines according to Table 7.

Table 7 – Dangerous zone when testing pipelines

2.22 Installation of electrical equipment and electrical networks

2.22.1 General requirements

2.22.1.1 Moving, lifting, and installing electric motors, electric-powered machines, and electrical switching devices must only be carried out when they are in a de-energized state.

2.22.1.2 Moving and installing electrical equipment must use specialized tools for anchoring. Steel wires, chains, and cables must not be used to tie insulating parts and contacts of foundation holes. Measures must be taken to prevent and resist tipping over. When transporting by vehicle, full measures must be taken to prevent breakage, abrasion, impact, and deformation, and to protect against rain, sun, especially for precision equipment with measures against collision, shaking, and vibration.

2.22.1.3 When transporting and gathering electrical equipment to the installation location, measures must be taken to preserve and protect against rain, sun, moisture, heat, dust, steam, or harmful substances.

2.22.1.4 Before installation, the position and stability of the supports and structural parts of the work at the installation location must be checked. During installation, transformers must have their output terminals short-circuited and those wire ends must be protectively grounded.

2.22.1.5 When using a crane to assemble electrical equipment, overhead power cables, lighting and power electrical networks within the working area must be de-energized and fenced off.

2.22.1.6 Lamps for checking the simultaneous closing of contacts must use a voltage not exceeding 12 V.

2.22.1.7 Within the area where centrifugal oil purifiers are installed and at the location of oil pouring equipment, “No fire” signs must be hung.

2.22.1.8 Installation of single-pole circuit breakers must ensure firmness and adjust the simultaneous engagement of the circuit breaker contacts.

2.22.1.9 Adjustment of circuit breakers must have measures to prevent the circuit breaker’s transmission parts from unexpectedly energizing for any reason.

2.22.1.10 Fuses of electrical networks connected to the assembled equipment must be removed throughout the construction period. Fuses can only be placed into the electrical network to adjust the equipment after everyone is in a safe position.

2.22.1.11 Before energizing to test the electrical grid and electrical equipment, all related work must be stopped, and people in the distribution room must leave the dangerous area.

2.22.1.12 Before testing remote-controlled parts by operating current or compressed air, “Danger – Live” signs must be hung on those devices.

2.22.1.13 When carrying out work inside the air receiver, a lock must be used to tightly hold the air inlet valve and a “Do not energize” sign must be hung.

2.22.1.14 The safety valve on the air receiver must be adjusted and tested with a pressure not exceeding the allowable pressure by more than 10%.

2.22.1.15 Applying voltage to test relays, automatic circuit breakers, and other devices must be done according to work orders and the instructions of technical staff after those devices have been tested.

2.22.1.16 Exposed parts of distribution equipment must be shielded, when there are no slabs on the power supply trenches, temporary wooden covers must be used. Electrical construction wires must not be allowed to come into contact with the work’s electrical wire parts.

2.22.2 Installation of Electrical Machines and Transformers

2.22.2.1 When using oil or gasoline to clean equipment parts, ventilation and fire prevention measures must be organized, and protective equipment must be available in accordance with current regulations.

2.22.2.2 Before measuring the resistance of a machine with rotating parts, the power circuit must be disconnected. There must be at least two people performing the work and checking to ensure there is no voltage on the machine. After assembly, the output leads must be short-circuited and protective grounding must be applied.

2.22.2.3 When drying or heating to test transformers and electrical machines, non-combustible insulating materials must be used. Electric-powered air blowers used for drying transformers and electrical machines must have spark protection devices.

2.22.2.4 Before drying electrical machines and transformers with electric current, the machine housing and oil tank must be protectively grounded.

2.22.2.5 When drying transformers by the induction method, measures must be taken to prevent electric shock. The possibility of people coming into contact with the induction coils must be eliminated. Open flames must not be used to read thermometers.

2.22.2.6 Repairs may only be carried out when the power circuit is disconnected. Repairing parts inside operating equipment is prohibited.

2.22.3 Installing and Charging Batteries

2.22.3.1 Any activities that may generate sparks are prohibited in the battery room. The battery compartment must use lighting lamps with a voltage of 6 V or higher and have an outer glass shell. The glass shell must have a supporting steel layer. Electrical wires must run in metal conduits and must be regularly inspected to prevent short circuits.

2.22.3.2 The battery room must be well-ventilated, and in addition to continuous artificial ventilation throughout the work process, it must also be ventilated for at least 30 minutes before and after work.

2.22.3.3 Food, drinking water, and other foodstuffs must not be stored at the location where acid, alkali, as well as lead plates are straightened, installed, or welded.

2.22.3.4 No other work may be performed in the electrolyte preparation room. The battery room must have a water tap or water tank. The rinse water and neutralizing solution containers must be placed on a stand and painted in colors for easy identification. The stands for acid and alkaline batteries must be lined with rubber.

2.22.3.5 Acidic electrolytes must be prepared in specialized jars. Acid solutions must not be prepared in glass bowls. Spilled acid, electrolyte, or alkaline substances must be neutralized and rinsed with boric acid solutions if it is an alkaline solution. Electrolyte solutions must not be transferred by mouth suction through pipes.

2.22.3.6 The room for work such as scraping sulfate off lead plates and straightening lead plates must be well ventilated. When scraping sulfate off lead plates, brushes or rags must be used. Direct wiping with hands is prohibited.

2.22.3.7 Lifting, moving, jacking stands, as well as placing or replacing pads, tank bottoms, and containers filled with electrolyte is prohibited.

2.22.3.8 When inspecting the terminal clamps of a battery, insulated rubber gloves must be worn. When tightening the nuts to connect the batteries together, care must be taken to prevent the wrench from touching different poles of the machine.

2.22.4 Installing Electrical Networks

2.22.4.1 When straightening metal wires using winches and other tools, it must be done in a separate area with surrounding fences and ensuring a safe distance from operating electrical equipment and lines.

2.22.4.2 Standing on leaning or folding ladders to horizontally tension conductors with a cross-section larger than 4 mm is prohibited.

2.22.4.3 Connecting multiple fuses with a small rated current instead of one fuse with a large rated current is prohibited. Installing one or two blown fuses into a 3-phase network is prohibited.

2.22.4.4 Power and lighting network lines must run separately.

2.22.4.5 Parts of electrical machinery and equipment must all be grounded if those parts may become live when the insulation fails.

2.22.4.6 Before starting to rotate the cable pulling drum, all protruding nails on the drum must be removed and the protruding cable end must be tightly clamped.

2.22.4.7 When placing cables, drums and other tools and equipment on the trench edge, the provisions in 2.12 must be followed. At the location of placing the drum and cable releasing equipment, measures must be taken to prevent trench wall collapse.

2.22.4.8 When releasing the cable from the drum using a winch or machine, a cable drum brake must be used.

2.22.4.9 When laying cables, standing or using hands to hold the cable at bends is prohibited.

2.22.4.10 Releasing underground cables using a winch through pulleys in a cable well or cable room on floors may only be carried out when there is an audible or visual signal.

2.22.4.11 When installing cable junction boxes with paint or Ebonite mixture, fire prevention measures must be taken for those substances.

2.22.4.12 When sealing cable ends and funnels or using gasoline to clean sheaths or cables in a confined room, proper ventilation and fire prevention measures must be in place.

2.22.4.13 When lighting a welding torch to melt bitumen and solder, it must be done outdoors. Molten bitumen and solder must be placed in sealed boxes and lowered into the basement using specialized tools.

2.22.4.14 Constructing overhead power transmission lines must comply with current regulations on the construction of electrical works.

2.22.4.15 Anchoring, tying lifting equipment or similar work to power poles is prohibited. When installing equipment near live lines, the provisions in 2.6 must be followed.

2.22.4.16 When erecting complex power poles using lifting equipment and tools, guy wires must be used for adjustment. Erecting and lowering poles in complex conditions between two live lines must be supervised by a construction technician.

2.22.4.17 During wire pulling or removal, people or vehicles are prohibited from passing through the wire crossing area, and a prohibition sign must be posted at this location. In case normal traffic must be ensured, safety measures must be taken.

2.22.4.18 During wire pulling, climbing on corner poles to perform any work is prohibited.

2.22.4.19 When using lifting towers or mobile ladders, the provisions in 2.8 must be followed.

2.22.4.20 When removing and installing overhead power lines, the circuit must be disconnected and mobile grounding must be applied at both ends and the middle of the line, so that the distance between grounding devices does not exceed 3 km; the mobile grounding device may only be removed when there are no people on the pole top.

2.22.4.21 Electrical lines or lifting cable lines must be placed at a height of not less than 4.5 m and not less than 6 m where vehicles pass.

2.22.5 Working in Operating Power Substations

2.22.5.1 Repairing and assembling electrical equipment in an operating substation may only be carried out when there is a work permit and the power to that equipment and related equipment has been disconnected.

2.22.5.2 When repairing and installing transformers in a substation, the low-voltage side must be disconnected to avoid transformer heating.

2.22.5.3 At the connection points of enclosed and open distribution equipment with protective grounding wires, clamps must be made or the paint must be cleaned at those points to clamp the mobile protective grounding wire with pliers. When attaching the grounding wire, it must be connected to the grounding terminal first and then to the housing of the equipment to be grounded. When removing the grounding wire, the reverse procedure must be followed.

2.22.6 Testing, Handover and Commissioning of Power Substations

2.22.6.1 There must be complete equipment history records and installation technical assurance documents, as well as technical safety requirements before putting electrical equipment into testing.

2.22.6.2 When testing insulators and cables as well as testing and adjusting the operation of local rectifier devices of transformers and current transformers, current regulations on the operation techniques and safe use of electrical equipment in enterprises must be followed.

2.22.6.3 Before testing the energization of installed distribution equipment, the condition of locks on doors, protective parts, warning signs, fire protection equipment, lighting, communication telephones and protective grounding must be checked.

2.22.6.4 When testing and energizing electrical equipment, barriers and warning signs must be in place.

2.22.6.5 When adjusting new electrical equipment for handover, measures must be taken to ensure personnel safety. When observing, one must stand away from live parts, stop working on live parts, and at the same time, shielding and warning signs must be placed in that area.

2.23 Demolition, Repair, and Expansion of Buildings and Structures

2.23.1 General Requirements

2.23.1.1 Before demolishing, repairing, or expanding a building or structure, the following must be carried out:

• Survey and accurately assess the condition of the foundation, walls, columns, beams, floors, ceilings and other structures of the building or structure;
• Survey and assess the risks of fire, explosion, toxic chemicals and the consequences of demolition, renovation and repair on human health;
• Survey, assess and have inspection measures for adjacent structures, assess the impact during and after demolition and renovation;
• Survey results must be documented as a basis for construction design.

2.23.1.2 Buildings and structures that are damaged and at risk of sudden collapse, but cannot be repaired immediately, must have reinforcement or support measures, or there must be barriers, prohibition signs for people and vehicles to pass through the dangerous area.

2.23.1.3 Before proceeding with demolition, the following must be done:

• Check and remove all bombs and explosives (if any);
• Recheck the entire electrical system, only use it if it is safe. In case the old electrical system cannot be handled, it must be removed and replaced with a new line to serve construction;
• Have measures to support structures that may suddenly collapse when demolishing the structure or removing parts related to that structure;
• Have measures to limit vibration when cutting, pulling, and dismantling structures.

2.23.1.4 The demolition area must have fences, prohibition signs for people and vehicles to pass through, and red warning lights at night. The fence must be 2 m high, surrounding the demolition area, and the entrance and exit must be strictly controlled.

2.23.1.5 When dismantling structures within operating facilities, measures must be taken to ensure overall safety.

2.23.1.6 When dismantling at night or in places with insufficient lighting, adequate lighting must be arranged. Electrical wires must be attached to separate poles and must not be attached to the structures being dismantled.

2.23.1.7 Dismantling of structures is prohibited in the following cases:

• When there is wind of grade 5 or higher;
• On two or more floors at the same time along the same vertical line;
• When there are people working below the area being dismantled without safety shielding measures.

2.23.1.8 When dismantling structures at heights, the dangerous area below must be fenced off and prohibition signs must be placed.

2.23.1.9 When carrying out dismantling, measures must be taken to prevent structural parts from suddenly collapsing. When cutting structures into small sections, measures must be taken to prevent the remaining parts from suddenly collapsing, and at the same time, measures must be taken to prevent the cut-off structural parts from hitting people.

2.23.1.10 When dismantling arches or protruding parts, scaffolding must be used. In case of standing on other structural parts of the building to dismantle, safety measures must be ensured.

2.23.1.11 When dismantling structures mechanically, all people must be prohibited from entering the machine’s pathways and along both sides of the pulling cable. Machines or equipment used for dismantling structures must be placed outside the collapse range of the structure. If using machines or equipment to pull down structures, they must be placed at least 1.5 times the height of the structure away from it.

2.23.1.12 Demolishing structures using the blasting method must have a specific design and must comply with the regulations in QCVN 02: 2008/BCT.

2.23.1.13 When handling damaged structural parts, especially high parts, safe construction measures must be established, and necessary protective equipment must be fully provided to workers.

2.23.1.14 When demolishing chimneys, brick pillars as well as wall sections higher than 1.5 m that are severely damaged, hand tools (chisels, hammers, etc.) must not be used for chiseling, but appropriate equipment and special construction methods must be used. Walls must not be pulled down onto the floor. Chimneys and brick walls must not be demolished by chiseling at the base.

2.23.2 Demolition of Cylindrical Vaulted Structures, Chimneys

2.23.2.1 Tall cylindrical structures must not be demolished using the blasting method or by toppling over unless the surrounding area is large enough for the structure to fall down safely.

2.23.2.2 When dismantling cylindrical vaults, it must be carried out from the top down on both sides; when dismantling spherical vaults or sail-shaped vaults, it must be demolished in strips no longer than 0.5 m in a circular pattern from the top to the base.

2.23.2.3 When dismantling vaults, a support frame for the vault support system must be made, and the provisions in 2.8 must be followed.

2.23.2.4 When dismantling furnace vaults, it must be done from scaffolding. Standing on the furnace vault for dismantling is prohibited. When dismantling furnace vaults, water must be sprayed to suppress dust.

2.23.3 Demolition of Walls

2.23.3.1 Walls must be demolished floor by floor, starting from the roof and working downward.

2.23.3.2 When necessary, unsupported walls must be braced when being demolished.

2.23.4 Demolition of Floors

2.23.4.1 When necessary, to prevent hazards, floorboards and working platforms must be provided for workers to walk and move during the demolition process.

2.23.4.2 Hazardous areas at open floor sections where materials may fall must be fenced off.

2.23.5 Demolition of Steel Structures

2.23.5.1 During the process of demolishing structural parts, the collapse of steel structures and reinforced concrete structures must be prevented.

2.23.5.2 Steel structures must be demolished floor by floor.

2.23.5.3 Parts of steel structures, after being demolished, must be gradually lowered and not dropped from a height.

2.23.6 Renovation, Repair

2.23.6.1 Before vertically extending structures or installing additional components onto structural parts that increase the load on the structural parts, all related structural parts must be rechecked. When necessary, appropriate reinforcement measures must be implemented to ensure safety.

2.23.6.2 When repairing parts on floors, holes in the floor must be covered or fenced off, and sturdy handrails must be installed between the bracing compartments.

2.23.6.3 When repairing gas pipelines, steam pipelines, etc., the tightness and snugness of the valve system must be checked throughout the repair process.

2.23.6.4 When repairing under vault shells, appropriate formwork and support systems must be in place for the vault. The repair area must be fenced off to prevent people from passing through.

2.23.6.5 When repairing operating furnaces, shielding plates or temporary partition walls must be used to avoid heat radiation and toxic gases.

2.24 Construction on Water

2.24.1 General Requirements

2.24.1.1 When working on or near water, attention must be paid to: Protecting workers from falling into the water; Rescue when someone falls into the water.

2.24.1.2 Safety measures must be taken when working on or near water with requirements for the following safety equipment:

• Protective fences, safety nets, safety harnesses;
• Life buoys, life jackets and rescue boats (or motorboats);
• Protection against other hazards such as reptiles (living near water) and other animals.

2.24.1.3 Piers, pontoons, bridges, bridge piers, walkways and workplaces at sites with work on water must meet the technical requirements of current National Technical Regulations and selected applicable standards.

2.24.1.4 Floating structures on water need to have shelters or huts to protect workers.

2.24.1.5 Floating equipment on water must be fully equipped with suitable life-saving devices such as: rescue ropes, hooks, buoys.

2.24.1.6 The types of rafts used must:

• Have sufficient strength to withstand the maximum load it will have to carry;
• Be tightly moored or anchored;
• Be easily accessible.

2.24.1.7 Steel floor surfaces must be treated to create friction or covered with non-slip surfaces.

2.24.1.8 All working surfaces must have protective fences.

2.24.1.9 Floating pipelines must have safe walkways.

2.24.1.10 Entering hydraulic pump rooms without notifying or being accompanied by someone is prohibited.

2.24.1.11 Winch ropes, tow ropes, buckets, cutters and boat mooring ropes must be checked daily.

2.24.1.12 Workers may only board and disembark vessels at safe wharves.

2.24.1.13 Workers must be regularly checked by roll call.

2.24.2 Boats

Boats for transporting workers and operators must meet the requirements of current National Technical Regulations and selected applicable standards.

2.24.3 Rescue and First Aid Procedures

2.24.3.1 Workers working on water must be provided with a number of health recovery kits, life jackets, etc.

2.24.3.2 Working alone on water is prohibited.

2.24.3.3 Workers must be trained on what to do in emergency situations.

3 IMPLEMENTATION ORGANIZATION

3.1 The Ministry of Construction is responsible for guiding the implementation and inspecting the implementation of this Regulation.

3.2 Local state management agencies for construction are responsible for inspecting and examining construction work in accordance with the provisions of this Regulation.

3.3 During the implementation process, if there are any difficulties or problems, agencies, organizations and individuals are requested to promptly report to the Ministry of Construction for guidance or amendment and supplementation.