Complete List of Welding Symbols: Explained With Diagrams

1. Scope

This standard specifies the representation method of welding symbols.

This standard is applicable to metal fusion welding and resistance welding.

2. Normative References

GB/T 5185 Designation of Metal Welding and Brazing Methods on Drawings;

GB/T 12212 Technical drawings – Dimensions, proportions and simplified representation of weld symbols.

3. Basic requirements

3.1 The welding symbol shall clearly indicate the weld to be described, and shall not add too many notes.

The representation methods of weld include weld graphic method and weld symbol annotation method.

Generally, the method of weld symbol marking shall be adopted.

If it is not clear to use only the weld symbol annotation method or the graphical method is simpler than the annotation method, the graphical method can be used.

3.2 The weld symbol is composed of basic symbol and leader, and auxiliary symbol, supplementary symbol and weld size symbol can be added if necessary.

The scale, size and representation method of graphic symbols shall comply with GB/T 12212;

See Appendix C (normative appendix) for the commonly used graphic methods in GB/T 12212.

3.3 When the professional standards specify the weld size and welding process, these contents shall be indicated in the weld symbol.

When the welding method is marked on the drawing, it shall be in accordance with Appendix B (normative appendix).

Those requiring post welding processing, such as spading, grinding and cutting, shall be indicated in the technical requirements.

4. Welding Symbols

4.1 Basic symbols

The basic symbol is the symbol representing the cross section shape of the weld, as shown in Table 1.

Table 1 Basic Welding Symbols

Serial NoSymbol nameSketch MapWeld symbol
1Rolled edge weld (fully melted rolled edge)

Note: incompletely melted rolled edge weld is indicated by I-shaped weld symbol, and the effective weld thickness S is added, as shown in Table 7
Rolled edge weldRolled edge weld 
2I-shaped weldI-shaped weldI-shaped weld 
3V-shaped weldV-shaped weldV-shaped weld 
4Unilateral V-shaped weldUnilateral V-shaped weldUnilateral V-shaped weld 
5V-shaped weld with blunt edgeV-shaped weld with blunt edgeV-shaped weld with blunt edge 
6Single V-shaped weld with blunt edgeSingle V-shaped weld with blunt edgeSingle V-shaped weld with blunt edge 
7U-shaped weld with blunt edgeU-shaped weld with blunt edgeU-shaped weld with blunt edge 
8J-shaped weld with blunt edgeJ-shaped weld with blunt edgeJ-shaped weld with blunt edge 
9Sealing weldSealing weldSealing weld 
10Fillet weldFillet weldFillet weld 
11Plug weld or slot weldPlug weld or slot weldPlug weld or slot weld 
12Spot weldSpot weldSpot weld 
13Seam weldSeam weldSeam weld 

4.2. Auxiliary symbols

4.2.1 Auxiliary welding symbols are symbols representing the shape characteristics of weld surface, as shown in Table 2.

Table 2 Auxiliary Welding Symbols

Serial NoSymbol nameSketch MapSymbolExplain
1Plane symbolPlane symbolPlane symbol The weld surface is flush
2Concave symbolConcave symbol Concave symbol Weld surface depression
3Convex symbolConvex symbolConvex symbol Raised weld surface

Note: When it is not necessary to specify the surface shape of the weld, auxiliary symbols can be omitted.

4.2.2 See Table 3 for application examples of auxiliary symbols.

Table 3 Application Examples of Auxiliary Symbols

Serial NoSymbol nameSketch MapSymbol
1Plane V butt weldPlane V butt weld Plane V butt weld 
2Convex X butt weldConvex X butt weld Convex X butt weld 
3Concave fillet weldConcave fillet weld Concave fillet weld 
4V-shaped weld of flat backV-shaped weld of flat back V-shaped weld of flat back 

4.3 Supplementary symbols

Supplementary symbols are used to supplement some features of welds.

See Table 4 for supplementary symbols.

See GB/T 5185 for symbols of welding process methods.

Table 4 Supplementary Symbols

Serial NoSymbol nameSketch MapSymbolExplain
1Symbol with backing plateSymbol with backing plateSymbol with backing plate Indicates that there is a backing plate at the bottom of the weld
2Three side weldThree side weldThree side weld Indicates that there are welds on three sides
3Peripheral weldPeripheral weldPeripheral weld Indicates welding around the workpiece
4Site Symbols Site Symbols Indicates welding on site
5Tail symbol Tail symbol Mark welding process method

Table 5 Example of supplementary symbol application

Serial NoSketch MapDimension exampleExplain
1Indicates that there is a backing plate at the bottom of the back of the V-shaped weldIndicates that there is a backing plate at the bottom of the back of the V-shaped weldIndicates that there is a backing plate at the bottom of the back of the V-shaped weld
2There are welds on three sides of the workpiece, and the welding method is manual arc weldingThere are welds on three sides of the workpiece, and the welding method is manual arc weldingThere are welds on three sides of the workpiece, and the welding method is manual arc welding
3It means welding around the workpiece on siteIt means welding around the workpiece on siteIt means welding around the workpiece on site

5. Position of welding symbols on drawings

5.1 Basic requirements

Complete weld representation methods include: basic symbol, auxiliary symbol, supplementary symbol, leader, dimension symbol and data.

The leader line includes: arrow leader line (arrow line) and datum line (a solid datum line and a dotted datum line), as shown in Fig. 1.

Complete List of Welding Symbols: Explained With Diagrams 1

Fig. 1 Leader line

5.2 Relationship between arrow line and welding joint

Two terms describing the relationship between arrow lines and joints are:

a. Arrow side of connector;

b. The non arrow side of the connector.

See Fig. 2 and Fig. 3 for descriptions of the two terms.

Complete List of Welding Symbols: Explained With Diagrams 2

(a) Weld seam on arrow side

Complete List of Welding Symbols: Explained With Diagrams 3

(b) Weld seam is on the non arrow side

Fig. 2 T-joint with single fillet weld

Complete List of Welding Symbols: Explained With Diagrams 4

Fig. 3 Cross joint of double fillet weld

5.3 Arrow position

Generally, there is no special requirement for the position of the arrow line relative to the weld, as shown in Fig. 4 (a) and (b).

However, when marking single-sided V-shaped, single-sided V-shaped with blunt edge and J-shaped welds, the arrow shall point to the workpiece with groove, as shown in Fig. 4 (c) and (d).

If necessary, it is allowed to bend the arrow line once, as shown in Fig. 5.

Complete List of Welding Symbols: Explained With Diagrams 5
Fig. 4 Location of arrow line
Complete List of Welding Symbols: Explained With Diagrams 6
Fig. 5 Curved arrow line

5.4 Location of reference line

The dotted line of the reference line can be drawn above or below the solid line of the reference line.

The datum line shall be parallel to the bottom edge of the drawing.

5.5 Position of datum mark relative to datum line

a. If the weld is on the arrow side of the joint, the basic symbol shall be marked on the solid line side of the datum line, as shown in Fig. 6 (a);

b. If the weld is on the non arrow side of the joint, the basic symbol shall be marked on the dotted line side of the datum line, as shown in Fig. 6 (b);

c. When symmetrical welds and double-sided welds are marked, dotted lines may not be added, as shown in Fig. 6 (c) and (d).

Complete List of Welding Symbols: Explained With Diagrams 7
(a) The weld is on the arrow side of the joint
Complete List of Welding Symbols: Explained With Diagrams 8
(b) The weld is on the non arrow side of the joint.
Complete List of Welding Symbols: Explained With Diagrams 9
(c) Symmetrical weld
Complete List of Welding Symbols: Explained With Diagrams 10
(d) Double side weld

Fig. 6 Position of basic symbol relative to reference line

6. Weld size symbol and its marking position

6.1 General requirements

6.1.1 If necessary, datum symbols can be provided with dimension symbols and data. See Table 6 for dimension symbols.

Table 6 Weld Size Symbols

SymbolSymbol nameExample diagramSymbolSymbol nameExample diagram
δWorkpiece thicknessWorkpiece thicknesseWeld spacingWeld spacing
αGroove angleGroove angleKFillet sizeFillet size
bRoot gapRoot gapdNugget diameterNugget diameter
PBlunt edgeBlunt edgeSEffective thickness of weldEffective thickness of weld
cWeld widthWeld widthNNumber of identical welds symbolNumber of identical welds symbol
RRoot radiusRoot radiusHGroove depthGroove depth
LWeld lengthWeld lengthhSurplus heightSurplus height
nNumber of weld segmentsNumber of weld segmentsβGroove face angleGroove face angle

6.1.2 The marking principle of weld size symbol and data is shown in Figure 7.

a. The dimensions on the cross section of the weld are marked on the left side of the basic symbol;

b. The dimension of weld length direction is marked on the right side of the basic symbol;

c. The groove angle, groove face angle and root gap dimension are marked on the upper or lower side of the basic symbol;

d. The number symbol of the same weld is marked at the tail;

e. When there are many dimension data to be marked and it is difficult to distinguish, corresponding dimension symbols can be added in front of the data.

Complete List of Welding Symbols: Explained With Diagrams 11
Fig. 7 Marking principle of weld size

6.1.3 See Table 7 for the example of weld size marking.

Table 7 Example of Weld Dimension

Serial No

Weld name

Sketch Map

Welding dimension symbol

Example

1

Butt weld

Butt weld

S: Effective thickness of weld

Effective thickness of weld

Butt weld

Effective thickness of weld

Butt weld

Effective thickness of weld

2

Crimping weld

Crimping weld

S: Effective thickness of weld

Crimping weld

Crimping weld

Crimping weld

3

Continuous fillet weld

Continuous fillet weld

K: Fillet size

Continuous fillet weld

4

Intermittent fillet weld

Intermittent fillet weld

L: Weld length, excluding crater; 

e: weld gap ;

n: number of weld segments

Intermittent fillet weld

5

Staggered intermittent fillet weld

Staggered intermittent fillet weld

L: Weld length, excluding crater;

e: weld gap;

n: number of weld segments;

 K: weld fillet size

Staggered intermittent fillet weld

6

Plug weld or slot weld

Plug weld

L: Weld length, excluding crater; 

e: weld gap; 

n: number of weld segments;

 c: slot width.

Plug weld

slot weld

e: Weld clearance;

 n: number of weld segments;

 d: diameter of hole.

slot weld

7

Seam weld

Seam weld

L: Weld length, excluding crater; 

e: weld gap; 

n: number of weld segments;

 c: weld width.

Seam weld

8

Spot weld

Spot weld

n: Number of weld segments;

 e: spacing;

 d: weld spot diameter.

Spot weld

6.2 Description of dimension symbols

6.2.1 The size for determining the weld position shall be marked on the drawing instead of being drawn in the weld symbol.

6.2.2 If there is no mark on the right side of the basic symbol and no other description, it means that the weld is continuous in the whole length of the workpiece.

6.2.3 If there is no mark on the left side of the basic symbol and no other description, it means that the butt weld should be fully welded.

6.2.4 When the plug weld and groove weld have beveled edges, the size of the hole bottom shall be marked.

7. Example of symbol application (see Appendix A)

Appendix A

(Informative appendix)

Example of symbol application

A. 1 Application of basic symbols

See Table A.1 for examples of basic symbols.

A. 2 Basic symbol combination

See Table A.2 for application examples of basic symbol combination.

A. 3 Combination of basic symbols and auxiliary symbols

See Table A.3 for examples of the combination of basic symbols and auxiliary symbols.

A. 4 Special cases

See Table A.4 for the marks of flared weld, unilateral flared weld, stack weld and lock edge weld.

Table A.1 Application examples of basic symbols

Complete List of Welding Symbols: Explained With Diagrams 12

Table A.2 Example of basic symbol combination

Complete List of Welding Symbols: Explained With Diagrams 13

Table A.3 Examples of combination of basic symbols and auxiliary symbols

Complete List of Welding Symbols: Explained With Diagrams 14

Table A.4 Marking of Special Welds

Complete List of Welding Symbols: Explained With Diagrams 15

Appendix B

(Normative appendix)

Welding method and its name

B. 1 Marking of welding method in drawings

When various welding methods are marked on the drawings, Chinese characters shall be used instead of the codes specified in GB/T 5185.

B. 2 Common welding methods and their names

Common welding methods and their names are as follows:

a) Manual arc welding (coated electrode MIG welding);

b) Submerged arc welding;

c) MIG welding: Molten inert gas protection welding;

d) MAG welding: Molten non inert gas protection welding;

e) TIG: Tungsten inert gas welding.

f) Spot welding;

g) Oxygen acetylene welding;

h) Energy storage welding;

i) Flame brazing;

j) Induction brazing;

k) Soldering (tin).

Appendix C

(Normative appendix)

Graphic method

C. 1 General

When it is necessary to draw the weld simply in the drawing, it can be represented by views, sectional views or sectional drawings.

This appendix describes the graphical methods commonly used by enterprises in GB/T 12212 for ease of use. See GB/T 12212 for more details.

C. 2 Views

C. 2.1 The drawing method of welds is shown in Fig. C.1 and Fig. C.2 (a series of fine solid line segments representing welds can be drawn by hand).

It is also allowed to use thick lines (2b ~ 3b) to represent welds, as shown in Fig. C.3.

However, in the same drawing, only one painting method is allowed.

Complete List of Welding Symbols: Explained With Diagrams 16
Drawing method of welds

C. 2.2 In the view representing the end face of the weld, thick solid lines are usually used to draw the contour of the weld.

If necessary, thin solid lines can be used to draw the groove shape before welding, as shown in Fig. C.4.

C. 3 Sectional view or sectional view

On the sectional view or profile view, the metal fusion welding area of the weld shall be generally marked in black, as shown in Fig. C.5.

If the shape of groove is required to be indicated at the same time, the fusion welding area can also be drawn according to Clause C.2.2, as shown in Fig. C.6.

Complete List of Welding Symbols: Explained With Diagrams 17
Fig. C.5
Complete List of Welding Symbols: Explained With Diagrams 18
Fig. C.6

Welding symbol examples

Complete List of Welding Symbols: Explained With Diagrams 19
I-shaped weld
Complete List of Welding Symbols: Explained With Diagrams 20
V-shaped weld
Complete List of Welding Symbols: Explained With Diagrams 21
Unilateral V-shaped weld
Complete List of Welding Symbols: Explained With Diagrams 22
V-shaped weld with blunt edge
Complete List of Welding Symbols: Explained With Diagrams 23
Single V-shaped weld with blunt edge
Complete List of Welding Symbols: Explained With Diagrams 24
U-shaped weld with blunt edge
Complete List of Welding Symbols: Explained With Diagrams 25
J-shaped weld with blunt edge
Complete List of Welding Symbols: Explained With Diagrams 26
Fillet weld
Complete List of Welding Symbols: Explained With Diagrams 27
Sealing weld
Complete List of Welding Symbols: Explained With Diagrams 28
Plug weld or slot weld
Complete List of Welding Symbols: Explained With Diagrams 29
Spot weld
Complete List of Welding Symbols: Explained With Diagrams 30
Plane connection (brazing)
Complete List of Welding Symbols: Explained With Diagrams 31
Seam weld
Complete List of Welding Symbols: Explained With Diagrams 32
Double V weld (X weld)
Complete List of Welding Symbols: Explained With Diagrams 33
Double sided single V weld (K weld)
Complete List of Welding Symbols: Explained With Diagrams 34
Double sided V-shaped weld with blunt edge
Complete List of Welding Symbols: Explained With Diagrams 35
Double sided single V weld with blunt edge
Complete List of Welding Symbols: Explained With Diagrams 36
Double U-shaped weld with blunt edge

Leave a Comment

Your email address will not be published. Required fields are marked *