Weld symbols and welding symbols are a means of communication between the designer and the welder. Therefore there must be a set of rules regarding representation of information on a welding drawing that must convey same information regardless of who reads it. This article discusses various aspects related to weld symbols and welding symbols.
The article begins by telling the difference between weld symbols and welding symbols, and proceeds to explain in brief about both.
Difference Between Weld Symbol And Welding Symbol
The terms weld symbol and welding symbol aren’t same. Weld symbol is a small mark that indicates the type of weld such as a seam weld, groove weld or fillet weld and so on. Sometimes this symbol may also indicate the type of joint such as a lap joint, or corner joint, or tee joint, or corner joint or butt joint.
The following figure shoes the various commonly used weld symbols used in the industry.
Welding symbol, on the other hand, is a broader term. It contains much more information than the type of weld or type of joint alone. The figure shown below is an example of a welding symbol.
As we can see, a welding symbol may depict type of finishing required on the weld, the location of the weld, the type of process to be used to make the joint, whether the weld is to be made in the field, or whether the weld is to be made all-round, pitch of the intermittent welds, length of the stitch weld, number of spot welds or projection welds, and so on.
However, the welding symbol may not depict all of this information. The amount of information depicted through a welding symbol differs in different circumstances. Typically, a welding symbol depicts the following eight elements: a reference line, an arrow line, a basic weld symbol, dimensions of the weld, finish symbol, supplementary symbols, tail, specification and process.
The positioning of these elements on the welding symbol is important. The generally used positions for these pieces is as shown in the above figure.
Basic Weld Symbols
The basic weld symbols used in arc welding and gas welding are shown in figure 1 above. The symbols used for resistance welding processes such as spot welding, seam welding, etc. are also indicated on the figure.
The symbols shown in figure 1 do not include weld symbols for forge welding, induction welding, flow welding, and brazing. When it is required to indicate that the weld is to be made by one of these processes, it is done so by mentioning a process reference in the tail of the welding symbol, as indicated in the figure below.
When it is required to indicate that the weld is to be made by a particular welding process, it can be indicated by mentioning an abbreviation of that process in the tail of the welding symbol, as indicated in the figure below.
The various letter designations for various welding processes are given in the table below. Use of these letter designations saves the need to write descriptive welding process, and saves space. Note that only a few commonly used processes have been included in this table.
| Welding Process | Letter designation |
| Stud welding | SW |
| Gas shielded stud welding | GSSW |
| Submerged arc welding | SAW |
| Gas tungsten arc welding | GTAW |
| Gas metal arc welding | GMAW |
| Shielded metal arc welding | SMAW |
| Carbon arc welding | CAW |
| Flux-cored arc welding | FCAW |
| Oxyacetylene welding | OAW |
When the designer does not wish to insist on use of any particular process to make the joint, no tail needs to be indicated, as illustrated in the figure below.
Other Common Weld Symbols
When a small circle appears at the intersection of the arrow and the reference line, it indicates that the weld is required to be made all-round. This may mean around the circumference of a part or around the perimeter of a non-circular part.
If a small flag appears at the intersection of the arrow and the reference line, it indicates that it is a filed weld; and needs/can/should be made in the field only.
The all-round symbol and the field welding symbol are illustrated in the figure below.
