Arc Welding 101: How many weld passes does it take?

A lot goes into determining the number of passes. First and foremost, you have to review your welding procedure specification (WPS) to see what the minimum or maximum pass number requirements might be. If the WPS does not specify, you're free to use as many or as few passes as your skills allow.

Here are some things that will determine number of passes:

• Travel speed. High travel speeds equal low weld volume. Low weld volume means you’ll need to make more individual weld passes.
• Weave width or oscillation. The same idea applies to weave or oscillation as it does to travel speed. The smaller the weave, the lower the volume; the lower the volume, the more individual weld passes you’ll need.
• Joint configuration. If all other parameters are the same, a bevel groove will need more passes then a V-groove.
• Electrode diameter and wire feed speed (WFS). Again, all other parameters being the same, larger-diameter electrodes or higher WFS will increase volume per pass and decrease the overall number of passes.

For example, a 3/8-in. welder qualification plate test completed in the 1G (flat) position might be done in as few as two passes or in as many as seven passes or more. Welds in either instance can be perfectly acceptable when made by a skilled welder.

That same joint in the 2G (horizontal) position would probably require a minimum of four passes but may take as many as nine or 10. You’ll achieve the same weld quality, but the number of passes just depends on your technique and comfort level with the orientation.

The same joint in the 3G (vertical) position typically requires a minimum of three passes but would be of equal quality if it took five to six passes.

Code books typically limit minimum and maximum pass size, and those limitations depend on the process, heat input requirements, material thickness, and position of welding.

I've given thousands of welder qualification tests, and welders almost always ask me how many passes they should use. My response is always no less than three and as many as it takes to ensure the groove is full and has no more then 1/8 in. of weld reinforcement (crown). Other than that, you're on your own.