Foreword

TCVN 5570:2012 replaces TCVN 5570:1991.

TCVN 5570:2012 was converted from TCVN 5570:1991 in accordance with the provisions of Clause 1, Article 59 of the Law on Standards and Technical Regulations and Point a, Clause 1, Article 6 of Decree No. 127/2007/ND-CP detailing the implementation of some articles of the Law on Standards and Technical Regulations.

TCVN 5570:2012 was compiled by the Institute of Architecture, Urban and Rural Planning – Ministry of Construction, proposed by the Ministry of Construction, appraised by the Directorate for Standards, Metrology and Quality, and promulgated by the Ministry of Science and Technology.

1. Scope of Application

This standard stipulates symbols for axes and line types on drawings of design documentation.

2. Referenced Documents

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

TCVN 8-20:2002 (ISO 128-20:1996), Technical Drawings – General Principles of Presentation – Part 20: Basic Conventions for Lines.

3. Line Types in Drawings

3.1. Lines in drawings must be uniform, clear and accurate for each line type.

3.2. Line types and line widths are specified in Table 1.

Table 1 – Line types in drawings

Line Type	Line Symbol	Line Width	Scope of Application
1. Extra thick continuous line		d	Section outline
2. Thick continuous line		d/2	Plan and elevation outline
3. Thin continuous line		d/4	Dimension lines, extension lines, leader lines, material symbols
4. Dashed line (chain line)		d/4	Interrupted lines for partial views
5. Long-dashed short-dashed thin line		d/4	Axis lines, center lines in drawings
6. Thin dashed line		d/4	Hidden lines
NOTES: 1. Line width d is taken according to the provisions in TCVN 8-20:2002. 2. The line widths in Table 1 apply to drawings with a scale of 1:50 and smaller. 3. For drawings with a scale larger than 1:50, the drawing scale must be used as a basis for selecting the line width.

4. Axes in Drawings

4.1. Axes in drawings are designated by numbers or letters in single circles (see Figure 1).

Numbers are written in Arabic numerals.

Letters are written in upper case printed letters, not using the letters I and O to avoid confusion with numbers.

The line width of letters and numbers is d/2.

Figure 1 – Example of axis symbols in drawings

4.2. The diameter of the symbol circle depends on the scale of the drawing and is specified as follows:

a) 6 mm for drawings with a scale smaller than 1:200;

b) 8 mm for drawings with a scale from 1:200 to 1:100;

c) 10 mm for drawings with a scale larger than 1:100;

d) The line width of the circle ranges from d/4 to d/3.

4.3. The order of writing letters and numbers for axis symbols and cases of using symbols are specified in Table 2.

Table 2 – Rules for writing letters and numbers in axis symbols

Figure 2 – Example of radial axis symbols

Figure 3 – Example of concentric axis symbols

4.4. In the case where the plan of the construction has an arbitrary shape, the principle of axis symbols is still based on the horizontal and vertical axes of the drawing, rotated clockwise for parts of the construction that do not lie in the orthogonal or circular system (refer to Appendix B).

4.5. In the case of using letters for symbols and there are not enough single letters, continue the symbols with two combined letters, starting again from AA, BB…

4.6. In the case of parts located between main axes, when it is necessary to place an intermediate axis, the intermediate axis symbol follows the template in Figure 1b.

APPENDIX A (informative) ORDER OF WRITING AXES ON THE VERTICAL AXIS SYSTEM

Unit: millimeter

Figure A.1 – Example of writing axes on the vertical axis system

Unit: millimeter

Figure A.2 – Example of writing axes on the vertical axis system

Unit: millimeter

Figure A.3 – Example of writing axes on the vertical axis system

APPENDIX B (informative) METHOD OF WRITING AXES ON AN ARBITRARY SHAPED PLAN

Unit: millimeter

Figure B.1 – Some methods of writing at different positions on the drawing

Unit: millimeter

Figure B.2 – Method of writing axes on an arbitrary shaped plan