Part Three: Hot pass on 6″ Sch. 40 pipe

July 11th, 2018
By Dave Lynnes

The second weld on a pipe is referred to as the hot pass.

I use 3/32″ 7018 electrodes to weld the hot pass and set the machine around 80 amps. Before you start welding the second pass, you must grind the root pass until you remove all the slag and the material is shiny.

I have found that the U-motion technique works the best for me when welding the second pass. I know some welders like to use a side to side motion, or a Z weave, and these techniques work fine.

When I weld the hot pass, I fill the groove until the weld is just under flush from the surface of the pipe. If you do not fill the groove enough, you may have a difficult time removing the slag.

At the end of each weld be sure to chip the slag, and strike the electrode in the bevel 1″ in front of the end of the weld, and long arc the electrode back to the crater, pause to fill the crater and continue welding. Repeat this each time you stop and start a new electrode.

The only grinding I do on the hot pass is on any high spots from the tie-ins, and I grind back the start of the first weld 1/2″ so I can get a good tie-in when I complete the last weld.

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