Abraham: At 45C minimum temperature, we're not sure why you're specifying A333 Gr. 6 pipe. This is not a particularly low temperature. Perhaps you mean -45C? David Hendrix The Hendrix Group Inc.

Abraham, For many process piping systems, it is my understanding that the preferred industry method of welding is to "TIG" the root and flux core arc fill (FCA) the rest of the weld. This ensures a smooth interior profile without the piping fitup problems of "chill rings" (consumable inserts) On nuclear plants, there was a visible inspection of the competed root........Plus, the fitters and welders like to do it this way, anyway.... On the power plant jobs I have seen, it was always the young kid, just out of tech school ( with the steady hand) that would TIG the root pass. The older guys (read "shakey"..) fitters and welders did not mind doing the remaining "stick work". See this link: http://www.twi.co.uk/professional/unprotected/band_1/gsp12886_launch.html My opinion only MJC