Abstract
The objective of this study is to ensure the safety of pressure vessels. It is very important to know the welding residual stress in order to maintain the safety of welded components and design an effective maintenance plan, including the fabrication process. Very thick welded joint is studied in this research, so the welding residual stress has complex distribution in the section. The inherent strain method combined with Finite Element Method (FEM) is applied to measure the welding residual stresses accurately.
One more subject is to examine the effect of stress-relief annealing (SR treatment) for the thick welded joint. So, two same mock-ups for a welded joint of pressure vessel were prepared for the study. As a practical measuring procedure of the inherent strain method, TL-method had presented. However, the method gives the determinate value of the residual stress, and does not give the most probable value and the deviation which are estimated by the original inherent strain method. So, the TL-method is improved to give them, allowing the reliability of the estimated results to be discussed.
The deviations of the estimated results are small enough for the most probable values. It assures the high reliability of the results. The residual stresses after the SR treatment are small enough, compared with the welding residual stresses. Sufficient effect of the SR treatment is confirmed.
