RT1 Stamp RT1 Stamp radd02 (Industrial) (OP) 1 Aug 17 12:09 do 100% RT box headers require a RT1 stamp on the code tags? RE: RT1 Stamp A clark (Mechanical) 1 Aug 17 14:38 First question, is this box header Section I or Section VIII construction? RE: RT1 Stamp radd02 (Industrial) (OP) 1 Aug 17 14:44 Section VIII Division 1 box header pressure vessel RE: RT1 Stamp yog993 (Mechanical) 11 Aug 17 06:45 What is the type of joint ? Refer UG-116 (a)(1)(e)(1) for RT1 marking, it's related to butt joints only. I think if its corner joint then RT1 is not required.