Ultrasonic stress evaluation through thickness of a stainless steel pressure vessel

•The main goal is ultrasonic evaluation of through thickness stresses.•Welding processes of a stainless steel pressure vessel are modelled by FE.•The hole-drilling method is used to validate the FE results.•Residual stresses are measured by four different series of ultrasonic transducers.•The comparison between ultrasonic and FE results show an acceptable agreement.

This paper investigates ultrasonic method in stress measurement through thickness of a pressure vessel. Longitudinal critically refracted (LCR) waves are employed to measure the welding residual stresses in a vessel constructed from austenitic stainless steel 304L. The acoustoelastic constant is measured through a hydro test to keep the pressure vessel intact. Hoop and axial residual stresses are evaluated by using different frequency range of ultrasonic transducers. The welding processes of vessel shell and caps are simulated by a 3D finite element (FE) model which is validated by hole-drilling method. The residual stresses calculated by FE simulation are then compared with those obtained from the ultrasonic measurement while a good agreement is observed. It is demonstrated that the residual stresses through thickness of the stainless steel pressure vessel can be evaluated by combining FE and LCR method (known as FELCR method).