Multiple Pass versus Single Pass? Part 4
As you make a multiple pass weld, several things happen for you. The first is that you will experience greater puddle control. In reality, for most steel welds, anything over 150 amps is wasteful energy, particularly in TIG.
In fact in TIG, most items don’t need much more than 90 amps to make a successful multi pass weld. That may seem low, but that would be the typical amperage (in TIG) that you’d weld a 3/32 filler with a 3/32 tungsten. Going larger than 1/8” Tungsten and filler with 120 amps really starts things cooking. But imagine cranking it on up to 200 amps with the 3/32 or 1/8” filler. You cannot “dab” fast enough to keep up with the demand of the weld.
Even if you use the “lay wire” technique you will find that you are running seriously short on filler. The same basic information applies to stick, though the amperage may range higher. For years one of the most revered welders on the pipelines has been a 200 amp engine drive welder. Rated at 200 amps (some models more) this is all that was ever needed. Now, of course there are bigger welders out there, with 300, 400, and even 500 amps but these are used for special applications like welding bridges etc, where massive amounts of heat energy is needed.
But for an average person, in an average shop, you won’t find that having this much amperage at your disposal will ever pay off. So if you are tempted to make one, thick, gobby pass, remember that you’ll likely spend more time redoing the weld, than you would have if you had taken a multiple pass to complete the weld.