An experimental investigation of the effect of defect shape and orientation on the burst pressure of pressurised pipes

Abstract

The burst pressure of commonly used ductile steel pipes in oil and gas industries, i.e. X52 and X60, is measured under internal pressure loading. The pipes were machined with circular and boxed defects at different orientations to simulate actual metal loss defects. Defect shapes and orientations were investigated in detail to study how they affect the failure behaviour of interacting defects. The experimental burst pressure results were compared with those obtained using existing analytical methods from Design Codes. Comparison of the results showed conservatism in the existing analytical methods which may potentially lead to unnecessary plant shutdowns and pipe repairs. The outcome of the experimental tests revealed that the shapes of the defects have very small influence on the defect interaction behaviour. The burst tests interestingly showed that the defect orientation has an important effect on defect interaction. Defects oriented in the hoop and diagonal directions showed no defect interaction even when spaced by a distance of one wall thickness, while defects oriented in the longitudinal directions showed that defects interact even when the spacing is up to six wall thickness but the interaction fades away for defects spaced at longer distances. Highlights Experimental 31 pipe burst tests with machined metal loss defects analysed  The effects of defect shape, orientation and interaction are investigated  Results compared with existing analytical methods from Design Codes  Degree of conservatism in the existing design codes discussed  Results show that defect orientation has an important effect on defect interaction

Burst Pressure Prediction of Subsea Supercritical CO2 Pipelines

“…The unflawed pipeline section is generally two concentric rings, and corrosion defects will cause the pipe wall thickness to be thinned. The types of corrosion defects that have been simplified in the literature are rectangular, parabolic, and point-shaped corrosion [ 37 , 38 , 39 , 40 ], but these simplified models make it difficult to conduct theoretical analysis. The theoretical analysis of the wear casing using the double circular arc (DCA) model is shown in Figure 2 in [ 33 ].…”

Effect of external wall defect growth on internal wall corrosion of oil pipelines under mechano‐electrochemical interaction

“…The Ramberg-Osgood constitutive relation can accurately reflect the stress-strain relationship of pipeline steel. [39,40] As shown in Figure 3, according to the Ramberg-Osgood rule, the true stressstrain curve of the X80 sample was fitted and its relationship is expressed as:…”

“…The Ramberg–Osgood constitutive relation can accurately reflect the stress–strain relationship of pipeline steel. [ 39,40 ] As shown in Figure 3, according to the Ramberg–Osgood rule, the true stress–strain curve of the X80 sample was fitted and its relationship is expressed as: where is the real strain, is the real stress, is Young's modulus (200 GPa), and is the yield stress (585 MPa). Coefficients and obtained from curve fitting are 1.563 and 14.86, respectively.…”

Buckling Analysis of Corroded Pipelines under Combined Axial Force and External Pressure

“…Yu et al [33] concluded that the loading path has a great influence on the ultimate load of the steel pipeline, and the p→T loading path is more serious than the T→p loading path. Although scholars have conducted a lot of research on the buckling of corroded steel pipelines, the formula for buckling pressure of corrosion steel pipelines under the combined action of external pressure and axial force is rarely involved [34][35][36][37], which is more convenient for engineering practice.…”