How to Call Out Welding on a Blueprint

A variety of welding instructions can be called out on blueprints.

Indicating the location, number and types of welding is a required element for blueprints that illustrate mechanical or structural creations made from metal. Welding components of these metal creations together forms much of the strength that allows the creation to function, and as such the proper indication of these welds on the plans is important. Though there are hundreds of potential weld and welding symbols that can be used, the basic ones will enable you to call out where welds should occur on a blueprint.

Instructions

1. Draw an arrow and leader line pointing to where the weld will occur.

2. Draw a horizontal reference line extending from the leader line.

3. Indicate specific instructions along the reference line, or create tail at the end of the reference line to indicate the welding process involved.

4. Draw a small triangle, called a fillet weld, on one side of your reference line to indicate which side of the joint the weld should occur on. Drawing the triangle on the top of the reference line indicates that the weld should occur on the side of the joint opposite the arrow. Drawing a triangle below the reference line indicates that the weld should occur on the same side of the joint as the arrow.

5. Draw the legs of the fillet weld proportional to how the joint should be welded. If the fillet weld triangle has equal length legs then the two joining metals of the joint will be welded equally. Drawing one leg longer than the other on the fillet weld symbol indicates that one component of the joint should be welded more than the other.

6. Add a number to the right side of the fillet weld symbol to indicate how long the weld should be.

7. Add a hyphen to the right of the weld length, followed by a number to indicate what the pitch of the weld, or the distance from center to center of the welds, should be.

8. Draw a circle around the intersection of the leader line and reference line if the weld should be an “all around,” meaning the joint should be welded all the way around.

9. Add a small diagonal line or curve, along with specific letters, along the slope of the fillet weld symbol to indicate the contour finish of the weld. The diagonal line indicates a flat contour while the curved line indicates a convex contour to the weld. Adding the letter “M” indicates “matching,” the letter “G” indicates grinding, and the letter “C” indicates “chipping.”

References

• "Blueprint Reading for Welders"; A.E. Bennett, et al.; 2008
• Welding Symbols: Delta School of Trades
• Welding.com: Section I. Print Reading