Welding on in-service pipes can be completed under various codes depending on the application and the jurisdiction where it is performed. One of the common requirements of these codes is that for welding on pipe with a thickness of less than 1/4” (6.4mm) that the potential for burn-through be controlled. In this paper, some of the common simulation and calculation methods were reviewed and discussed. Modiﬁed tests for welding procedure qualiﬁcation of thin wall in-service application were proposed and successfully qualiﬁed as per applicable code requirements. The qualiﬁed procedures were Welding Engineer, ProForma Engineering Ltd. used in the ﬁeld to weld on thin-wall gas applications and successfully passed the quality inspection acceptance criteria.
The qualiﬁcation testing results showed that, in contrary to the calculation and simulation results, it is possible to safely weld thin wall in-service conditions by controlling key process parameters such as weld heat input, cooling rate, welding sequence and good workmanship.