Analytical Approach for Buckling Resistance of UOE Linepipe With Orthogonal Anisotropy Under Combined Loading

Abstract

UOE linepipes have orthotropic work hardening in which the longitudinal (L-) stress vs. strain (SS) curve is different from the circumferential (C-) one. The anisotropy is emphasized by the thermal aging during the anti-corrosion coating. However, there are few studies on the effect of the circumferential mechanical properties on the compressive strain limit required in strain-based design (SBD). This paper describes the combined effect of SS curves in L- and the C-direction on the buckling resistance using the newly developed yield function to model the orthogonal anisotropy. The coupon tests after thermal aging during the anti-corrosion coating indicate that the L-SS curve can maintain the round-house type while the long yield point elongation (YPE) appears on the C-SS curve. Using these mechanical properties, FE-models demonstrate that YPE in the C-direction reduces the compressive strain limit for pipes with high diameter/thickness (D/t) under high internal pressure. Hence, SS curves in the C-direction should be considered for more reliable prediction of the buckling resistance required in long distance gas pipelines.

Modelling of anisotropic hardening behavior for the fracture prediction in high strength steel line pipes

“…From this, through Eqs. (11) and (12), it is possible to obtain the anisotropic coefficients in the other directions and the correspondent hardening all over the strain range up to fracture.…”

“…A different approach was proposed by Stoughton et al [10], which used a variable M exponent applied to the classical Hill's 79, Hosford's 79 and Barlat's 91 criteria, to calibrate the anisotropic hardening in Aluminium alloy sheets. Specifically for pipeline steels, Tsuru et al [11] proposed a modified Hill48 criterion with four out of six variable coefficients (the three direct components and only one shear) dependent from the plastic strain to describe the non-uniform hardening. Also in this case the Lode angle sensitivity was not taken directly into account.…”

New Environmentally Friendly Solutions to Prevent Oil Pipelines Disasters

“…2b. Therefore, the material presents strong out-plane anisotropy because of manufacturing process employed to produce the pipe (UOE) [8]. For the present study, the material was assumed to be general isotropy because of nature of the loading mode.…”

Modeling of plasticity and fracture behavior of X65 steels: seam weld and seamless pipes

“…In the advent of a new generation of high strength steels (HSS), this yield criterion has fallen short in predicting ductility and plastic flow in finite strain settings. This has motivated a number of improvements of the original model where additional capabilities have been inserted over the years with successful results (Suh, Saunders and Wagoner, 1996;Rivalin et al, 2000;Tsuru et al, 2008;Iizuka, Hashimoto and Kuwabara, 2014;Iob, Campanelli and Coppola, 2015). Meanwhile, from the fundamental work of Barlat et al (Barlat, Lege and Brem, 1991) and Karafillis and Boyce (Karafillis and Boyce, 1993), various non-quadratic yield functions have been developed to accounting for anisotropy in many materials such as aluminum and steel alloys.…”