Pipe Welders and Boilermakers use a Tig welding technique called the "lay wire" technique.
What it means is that the tig welding filler wire is held in the weld puddle all the time instead of being dipped in and out as will traditional tig welding techniques used for sheet metal.
Pipe welding is different from sheet metal welding and pipe welders are a different breed than those who weld sheet metal.
For one thing, Pipe welders often use a technique known as "walking the cup". This is a technique that works especially well for pipe and not a whole lot else.
Aerospace welders, motorsports welders, sheet metal welders, and most other job shop tig welders do not find much use for walking the cup. But the lay wire technique can be useful for lots of jobs.
Any tig welding job where the thickness is more than 1/8" inch or.125"...or about 3mm might be able to be done using this method. Especially if pulse parameters are used.
A note of caution: There is always a risk of lack of fusion when you use this technique on fillet welds because leaving the rod in the puddle can chill the puddle and can conceal the leading edge of the puddle making it difficult to ensure proper fusion all the way into the root.
I have heard of recent failures in socket welds where lack of fusion in the root was a contributing factor to the failure and socket welds are very often welded using the lay wire method.
But a socket weld on a power plant that goes through thermal mechanical fatigue is much different that a bracket for your headers on a hot rod project.
So the bottom line is this: use the lay wire method scrupulously. Like when aesthetics are the important thing. When absolute complete fusion is required all the way down in the root of a fillet weld, the dip method rules.
Links of Interest
Maintenance Storage
Coachings
What it means is that the tig welding filler wire is held in the weld puddle all the time instead of being dipped in and out as will traditional tig welding techniques used for sheet metal.
Pipe welding is different from sheet metal welding and pipe welders are a different breed than those who weld sheet metal.
For one thing, Pipe welders often use a technique known as "walking the cup". This is a technique that works especially well for pipe and not a whole lot else.
Aerospace welders, motorsports welders, sheet metal welders, and most other job shop tig welders do not find much use for walking the cup. But the lay wire technique can be useful for lots of jobs.
Any tig welding job where the thickness is more than 1/8" inch or.125"...or about 3mm might be able to be done using this method. Especially if pulse parameters are used.
A note of caution: There is always a risk of lack of fusion when you use this technique on fillet welds because leaving the rod in the puddle can chill the puddle and can conceal the leading edge of the puddle making it difficult to ensure proper fusion all the way into the root.
I have heard of recent failures in socket welds where lack of fusion in the root was a contributing factor to the failure and socket welds are very often welded using the lay wire method.
But a socket weld on a power plant that goes through thermal mechanical fatigue is much different that a bracket for your headers on a hot rod project.
So the bottom line is this: use the lay wire method scrupulously. Like when aesthetics are the important thing. When absolute complete fusion is required all the way down in the root of a fillet weld, the dip method rules.
Links of Interest
Maintenance Storage
Coachings
