Comparison of measured and modelled residual stresses in a welded P91 steel pipe undergoing post weld heat treatment. (March 2020)

• Record Type: Journal Article
• Authors: Yaghi, Anas H.; Hyde, Thomas H.; Becker, Adib A.; Sun, Wei; Wen, Wu; Hilson, Gabrielle; Simandjuntak, Sarinova; Flewitt, Peter EJ.; Pavier, Martyn J.; Smith, David J.
• Is Part Of: International journal of pressure vessels and piping. Volume 181(2020)
• Publication Date: 2020-03
• Subjects: P91 steel pipe -- Finite element -- Residual stress -- X-ray diffraction -- Deep-hole drilling -- Post weld heat treatment; Pressure vessels -- Periodicals; Pipe -- Periodicals; Récipients sous pression -- Périodiques; Tuyaux -- Périodiques; Pipe; Pressure vessels; Periodicals; 681.76041
• DOI: 10.1016/j.ijpvp.2020.104076
• Languages: English
• ISSNs: 0308-0161

Abstract

Abstract: The process of fusion arc welding of steel pipes in power generation plants induces residual stresses which may be detrimental to the integrity and endurance of plant pipelines. P91 is high-grade steel used in the construction of pipelines carrying hot steam at high pressure, conditions which cause creep during service. Welded P91 pipes are usually subjected to post-weld heat treatment (PWHT) to mitigate the magnitude of residual stresses and temper the material, hence improving its resistance to creep. In this paper, the finite element (FE) method of modelling residual stresses due to PWHT in a circumferentially butt-welded P91 pipe is presented. The PWHT hold temperature is 760 °C. The paper describes the X-Ray Diffraction (XRD) and Deep-Hole Drilling (DHD) experimental techniques and how they are applied to measure residual stresses in the welded P91 pipe after PWHT. The material property data, necessary for the FE simulation of PWHT, has been obtained from stress-relaxation tests on P91 uniaxial tensile specimens at 760 °C. Good agreements have been achieved between the results of the FE method and the two sets of experimentally-measured residual stresses. Highlights: Finite Element simulations of residual stresses in welded 91 pipes are presented. Post-weld heat treatment (PWHT) incorporated in the analysis. FE residual stresses are compared with two sets of experimental measurements. Good agreements achieved between FE predictions and experimental data.