Numerical and Experimental Residual Stresses of Different Welded Joint Configurations in Heavy Wall

Abstract

Refinery equipment subjected to high pressure is commonly made of Vanadium high strength steels (2¼Cr1Mo¼V), characterized by high allowable stress and low toughness in the as welded condition, leading to potential wall cracking before the application of thermal treatments. Therefore, the decision to perform specific thermal treatments after welding is of paramount importance. These thermal treatments, which are quite expensive and time demanding for the manufacturer, are still under discussion and not supported by evident scientific findings. The paper presents a numerical and experimental study on a plate-to-plate weld and on a nozzle-to-plate weld, created as ad-hoc mock-ups. Experimental residual stresses are collected by an X-ray diffractometer in the as welded configurations. These values are used to validate a complex 3D numerical model, implemented with the finite element software Abaqus and its AWI plugin. Finally, this validated model allows for the identification of joint criticality through two parameters: the volume of plasticized material per unit of welded length and the strain-based assessment according with ASME code. Their application as tools to compare the criticality of different welded geometries and the effect of thermal treatments on the residual stress field are discussed.