Gentlemen ,
I have found by X-Ray so many weld defect such porosity and LOF between 7 to 9 clock position  in stainless steel piping
Thickness 4mm and I am looking to grind all the welding passes from7 to 9 clock position and re weld again root , inter , filling ,reinforcement pass .

My concern about the welding quality and how to maintain purging gas through half weld