Evaluation of welding residual stress in a nickel alloy pressure vessel using the ultrasonic stress measurement technique

Welding of nickel-based alloys is increasingly used in industry to manufacture many important components of the marine and chemical processing industries, and so on. This paper investigates the implementation of an ultrasonic stress measurement technique in a pressure vessel constructed of a nickel-based alloy. A critically refracted longitudinal wave, an ultrasonic wave propagating beneath and parallel to the surface, was employed to measure the welding residual stresses. A hydro test process was used to measure the acoustoelastic constant, which is known as a principal parameter in ultrasonic stress measurement. The ultrasonic scanning path was in axial and circumferential directions to measure the axial and hoop residual stresses of the pressure vessel, respectively. The results of this ultrasonic technique were validated using hole drilling stress measurement. It was concluded that there was acceptable agreement between the hole drilling and ultrasonic stress measurements in the axial and hoop stress evaluation of the nickel alloy pressure vessel.