Optimization of residual welding stresses in austenitic steel piping: prooftesting and numerical simulation of welding and postwelding processes

The development/modification and qualification of welding technology for ge nerating compressive stresses in austenitic stainless steel piping welds ar e discussed. The following welding processes are considered: 1. A modified, orbital gas tungsten are (GTA) narrow-gap welding process wi th significant improvements over conventional and standard narrow-gap orbit al pipe welding, 2. The heat sink welding (NSW) process with internal cooling of the pipe wi th water or liquefied CO2 gas, and 3. The postwelding process. Last pass heat sink welding (LPHSW) for alterin g residual stresses in an existing weld. Residual stresses have been measured by using the so-called ring-core as we ll as radiographic procedures. In support of experimental work required to qualify these welding techniques a numerical simulation effort was undertak en. (C) 2000 Published by Elsevier Science S.A. All rights reserved.