Numerical analysis of the burn-through at in-service welding of 316 stainless steel pipeline

• To evaluate the risk of burn-through, the critical level of 980 °C is not only sufficient.
• We find that the mechanical stresses also play a major role in the burn-through.
• The effective stress should be compared against the temperature-dependent yield stress.
• The geometry of welding passes has a major role in the occurrence of burn-through.
• The risk of burn-through is high during the first pass than the second pass.

The purpose of this study is to develop an appropriate numerical model to predict the onset of the failure of a pipeline-wall during an in-service welding process. Therefore, the thermo-mechanical stresses as well as the temperature across the pipe wall have been obtained and the former have been compared against the temperature-dependent yield stress of the material. The results show that this is a more accurate criterion in order to check the burn-through risk and when the effective stress at two thirds of the pipe wall thickness is larger than the yield stress at the associated temperature, there is a risk of burn-through. The results show that burn-through may occur under the welding pool, and it is more likely to happen in the primary passes of the welding.