When I learned how to weld pipe I was an apprentice in the pipe and steamfitters local 540(Newport news Va). I couldnt get much info out of the old heads there, they had all the knowledge on lockdown like it was guild secrecy or something. Later I went to community college school on my own, but the instructor was sortof a dumbass.
So my question is, what exactley is a hot pass? When I welded(or mostley grinded) pipe, we used ( assuming the pipe preperation allowed for it) 1/8 6010 for a root, 3/32 6010 to clean out the root, and then 3/32 7018 to fill/cap. The whole time the machine were set on 90 to 110 amps. Was the 3/32 6010 pass the "hot pass"? after that job I switched over to structural welding and havent heard of a hot pass since. So I have always wondered. Anybody got the goods on this method?