If you re welding stainless steel pipe with a traditional process like tig or stick it likely requires a back purge with argon gas.
Tig welding stainless steel pipe purging.
But the cost of the gas and the setup time for the purging process can be significant especially as the pipe diameters and lengths increase.
Purging the weld is the best way to protect the inside of pipes from oxidation.
This process also uses shielding gas against contamination but you can weld thinner metals more efficiently with it.
Tig welding stainless steel is performed by using a non disposable tungsten electrode with a tig welder for striking up the arc.
Purging during tig welding is a process that envelopes the weld area with a non reactive gas such as helium or argon minimizing oxidation of the base weld area.
Welding stainless steel tubes and pipes typically requires back purging with argon gas when using traditional processes such as gas tungsten arc welding gtaw and shielded metal arc welding smaw.
Any welded stainless steel pipe application requires shielding the back of the weld as well as the front when tig welding.
A back purge removes contaminants and provides backing but it also adds significant time and money.
Aquasol water soluble paper provides an excellent barrier used to retain noble gases such as argon and helium within the weld zone during tig welding of stainless steel and aluminum pipes.
I take it your talking about tig welded root runs.
Most weld purging is carried out on joints made by the tig or gtaw welding process.
Purge gas backing fluxes fight off oxygen purging stainless steel pipe with ar gon or nitrogen for 300 series alloys with less than 10 percent nickel re quires the purge gas to flow long enough to displace the air from the pipe and create an atmosphere of less than 1 percent oxygen.
At first you re required to appropriately configure your welder.
When the laser welding process is chosen joints or welds being made on reactive materials will need to be carried out and in the case of electron beam welding this is carried out in a vacuum in which case purging takes place by complete evacuation of all gas.
Solar flux is one flux cored wire is another.
Solar flux is a powder that is mixed with methanol to form a cream like paste which is then painted onto the inside of the pipe plate.
There are a couple of ways to weld stainless steel without purging the back of the weld.
Crevice corrosion of the pipe.
