Scratch start tig?

Date 12-07-2002 05:28

When welding stainless pipe putting the rootpass in i am having probs. For one right off the bat starting the stupid thing i contaminate the dam tungsten. For two when i am to my final stretch point around the pipe and i need to pull out there is now way to stop the ark and let post gas flow on the molten stainless and it becomes all black and nasty and contaminated also. Now these guys are expecting x-ray quaulity welds from me and i can't consistently do good restarts so i'm off the stainless for right now. I am grinding and feathering the restarts also with a regular grinding wheel is this bad i think it is? The machine has no push button remote on it either in case u all where wondering about that and they do not use foot pedal remote in the shop because u can't use them in the field. I also know these guys can do this and i am guessin there stuff x-rays so r there any tricks out there any of u would like to shair? Thanx R.C.

By Lawrence (*****)

Date 12-08-2002 01:06

Trick #1 Watch the salty dogs do it

Trick #2 When walking the cup make sure you have a blunted end to your tungsten.

Trick #3 Watch the old salty dogs scratch start, paying close attention to where the electrode actually touches the work and at what angle the torch is held. Observe also the cup sizes they employ for each pass - root to cap. Tungsten stickout is critical to each.

Trick #4 Watch those old timers finish off the welds, notice how they change the torch angle as they "tail off the arc". When they finish each weld, quickly (before they wire brush) look at how the profile of the melted puddle gets smaller and smaller and works itself either to nothing (no pinhole or riser) or rides right off the toe.

That is what you need to emulate. This can be practiced with no filler on an old piece of pipe OD. just start at the bottom (6 O'Clock) and work your way to the top without rotating the pipe. Do lots of starts and stops.