A new thermo-mechanical approach to predict “burn-through” during the in-service welding

Abstract

Burn-through is one of the major concerns in the industry when carrying out in-service welding. For this reason, a new thermo-mechanical model is developed to calculate the temperature and stress distribution in the weldment of a T-shape pipe joint. Experimental data is used to validate the model. The results of the in-service welding simulation reveal that the currently used Battle's criterion is not safe enough for predicting burn-through, because it does not take into account the thermo-mechanical stresses. Also, results show that there are some cases with a high risk of burn-through despite satisfying Battelle's criterion, whereas, the new model is capable to identify these cases. If it is difficult to use this new model in the industrial environment, it is recommended to use Battelle's criterion with lower threshold temperature (800 °C instead of 982°C) especially for alloys with low thermal conductivity and those with a low ultimate tensile strength at high temperatures.