GAS Purging for Weld Root Control in Pipe Welding

Abstract

For many pipe welding applications, the physical characteristics of welds may not be important. Fillet and non fully penetrating welds have inherent crack like defects but these are seldom of any consequence. In circumstances where joints have to be designed to withstand stress in sen/ice or they need to be free from the risk of product entrapment or they need to be able to offer good flow characteristics, however, special consideration needs to be given to metallurgical aspects and to weld profile. The mechanical properties of welds, particularly their fatigue properties, can be influenced significantly by their shape and composition. In particular, at the weld ischolar_main, a positive reinforcement combined with smooth transition from weld to parent material are pre-requisites if optimum mechanical strength, flow characteristics and lack of product entrapment are to be realised. Gu idance on weld ischolar_main profile control for linear butt welds is provided elsewhere. Here we examine solutions when making tubular butt welds.