Strain Capacity of 48' OD X80 Pipeline in Pressurized Full-scale Bending Test

摘要

This paper presents the results of experimental studies focused on thernstrain capacity of X80 linepipe. A full-scale bending test of X80 grade,rngirth welded 48" high-strain linepipe pressurized to 60% SMYS wasrnconducted to investigate the compressive strain limit and tensile strainrnlimit. The compressive strain limit focused on the critical strain at thernformation of local buckling on the compression side of bending. Onernlarge developed wrinkle and some small wrinkles on the pipe surfacernduring bending deformation were captured relatively well fromrnobservation and strain distribution measurement. The tensile strain limitrnis discussed from the viewpoint of competition of two fracturernphenomena: ductile crack initiation/propagation from an artificial notchrnat the HAZ of the girth weld, and strain concentration and rupture in thernbase material at the tension (opposite) side of the local bucklingrnposition.rnA curved wide plate (CWP) test and full-pipe tension test were alsornconducted to investigate the tensile strain capacity of the girth weldedrnjoint under tensile load using relatively small diameter X80 pipeline.rnCrack initiation and propagation behavior was clarified satisfactorily byrnsectional observation of the surface notch at the HAZ of the weldedrnjoint. Tensile fracture limits related to the maximum load are discussedrnfrom the viewpoint of the effect of internal pressure by comparing thernCWP and full-pipe tension test results.