What makes you think purging is not required when using SMAW?
The reason for purging is to avoid oxygen in the weld and adjecent area(when above a certain temperature, which to my understanding is relative low)
When using SMAW, the flux will protect the weld itself, but not the adjecent area.
So it really depends on the piping systems intended service, if purging is required or not.
3.2
On a side note, it really looks bad when using capital letters. :)
By tighand430 
Date 02-11-2009 16:47
Edited 02-11-2009 16:50
The bead on the inside is protected by the slag. Since tig with bare wire doesn't have any kind of flux, you have to purge to keep the oxygen from reacting with the stainless. Local purging on the back side is not detrimental to the steel. Only problem doing it is usually getting the shielding gas to where it's needed and the asphyxiation hazards to the person on the inside.
