How to write a weld symbol

Written by grant d. mckenzie
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How to write a weld symbol
Welders rely on engineering welding symbols to do the job right. (soudure a l"argon image by Clément Billet from

Engineers and drafters provide instructions on how to build an item to the builders using engineering drawings. These drawings must provide enough information that the builders can properly construct the item without guesswork. In metalworking, and particularly in welding, engineers and drafters must convey a lot of information in a limited amount of space. They use a standardised set of symbols that can tell the technicians everything they need to know to get the weld right.

Skill level:

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Things you need

  • Engineering drawing
  • Pencil

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  1. 1

    Determine exactly what kind of weld you want. Know the size of the weld, the required process, depth and any other information necessary to communicate your instructions to the manufacturers.

  2. 2

    Draw a reference line near the location of the weld in the drawing. Depending on the orientation and the amount of open space, this reference line may be either horizontal or vertical. Angled lines are rare, but they are accepted in some cases. The line should be long enough to contain all the information, in symbol form, from step one.

  3. 3

    Draw an arrow to the weld in the drawing from the end of the reference line. If you are using a bevel or J-groove weld, the arrow must have a definite break and point to the edge that is to be chamfered for the weld. Any lines you draw must be straight. Curved lines are not acceptable.

  4. 4

    Draw the symbol for the type of weld. If the weld is going to be on the same side as the arrow, draw the symbol on the centre of the reference line on the side closest to the reader. If the weld needs to be on the opposite side from the arrow, draw the symbol on the centre of the side farthest from the reader. Symbols vary depending on the type of weld. Some of the most common are a right triangle for a fillet weld, a 45 degree angle with one leg perpendicular to the reference line for a bevel weld and a 90 degree "V" for a V weld. You can find charts with all the standard symbols in most welding references.

  5. 5

    Draw a half-diamond tail on the reference line on the opposite side from the arrow. In the angle formed by the tail, write in the symbol for the type of welding process to be used. Many times this is not necessary and therefore omitted. In that case, the manufacturer will use the best method for the materials and type of weld. Some examples of process symbols are "TB" for torch brazing, "BMAW" for bare-metal arc welding and "SW" for stud welding. You can find charts with all the standard symbols in most welding references.

  6. 6

    Add any other information to the reference line that will be required to produce the weld you want. The notations should read from right to left on the reference line. This may include items such as the length of the weld, the type of finish on the weld, the angle of the chamfer or "V." These notations should follow standard drafting conventions.

Tips and warnings

  • This information will help with most basic weld symbols. For welds that are more intricate, you should refer to standard welding references to ensure all the symbols are correct and in the right place.

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