Plasma Arc Welding - not in North America?

[trainguy]

Hello welding experts,

Does anyone know why modern North American structural welding standards do not cover Plasma Arc Welding since the mid-70's? Have we decided it is no good? Has it gone out of favour?

tg

 

[gtaw]

Plasma welding is one application that works best when it is either mechanized or automated. I have several clients that use the process, but in each case it has been mechanized.

Best regards - Al

 

[weldstan]

Agree with gtaw.

 

You will never see PAW in structural welding, but I think you don't mean just strictly structural standards.
gtaw and weldstan are correct, you tend to see it mechanized only. The difficulty is the extra quality of fit-up demanded, particularly with the keyhole plasma technique.
I did however once review some SS welding procedures for a Belgian pressure vessel maker and I must say I was impressed. The shell joints had a kind of hybrid design, with a fairly substantial land and zero root gap. The root was done with plasma and the balance (where there was a V-bevel) with a more conventional process, IIRC GMAW.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[meltedEng]

PAW is used in advanced ASME pressure vessel manufacture. We have 2 PAW machines for ASME work. Often used on advanced alloys and simple alloy as well. Many customers are hesitant of the process due to the new and changing technology and most customer do not have welding engineer to advise them, or experience with it.

It is rare in all of world to use it.

PAW is amazing process, but you could not use these at site due to technology and set-up/knowledge required. Also needs no wind. It is not nearly as easy at site as setting up a sub-arc beam/crawler etc.