i'm sorry, i was not able to reply sooner. i had problem with the log-in.
actually, pipes (a500 gr.b) are welded to another material (a668 gr.b). the second material is machined to fit around 10mm inside the pipe leaving around 3mm gap for the weld (serves as backing). as required, we were told to qualify 20mm plate as in fig. 4.25 (b).
welding process - GMAW (semi-automatic). i'm not sure if which applies, Flat (1G) or Flat (1G) Rotated. Pipes were rotated while welding gun is stationary. however, for the plate, it was the other way around.
again, please help.
thank you very much.