Q.I have always enjoyed your column inbut I don't think you answered Stan Collin's question (in the July '19 issue) about using a copper backup pad for welding up small holes. You did give some great ...

It is important when welding metals such as stainless steel, titanium and zirconium that the welding zone is purged of oxygen even as low as 10 parts per million (ppm) before, during and immediately ...