Experimental and Numerical Investigation of Heated Band Width for Local Post Weld Heat Treatment of ASME P92 Steel Pipe

Local post weld heat treatment (local PWHT) is usually carried out when it is impractical to place the entire component in a furnace or oven, which is an effective way to relax residual stress due to welding. However, there are various international codes or standards that define different criteria for local PWHT and it may bring confusion in engineering applications. In the present study, welding and local PWHT experiments on ASME SA-335 Grade P92 large-diameter pipes were conducted under field conditions. In order to simulate the temperature field distribution of welded joints during the process of local PWHT, a thermal tracking program has been successfully developed using the ANSYS parametric design language (APDL) and the numerical results agree well with experimental data. Furthermore, a series of pipe models were developed using the finite element method (FEM) and through repeated calculations, optimized numerical values for each pipe's heated band (HB) width and gradient control band (GCB) width were calculated. Through numerical analysis, recommended estimation of heated band width for local PWHT of P92 large-diameter pipes is obtained, which ensures the minimum temperature throughout the soak band.