The mechanical behavior of internally pressurized pipes with volumetric flaws is analyzed. The two possible straining modes are identified and each is studied by means of an idealized flaw: the bending strain is associated with axis-symmetric flaws and the membrane strain to narrow axially oriented flaws. Linear elastic shell solutions for stress and strain are proposed. The plastic behavior is studied and equations for predicting the pressure at which the pipe fails by plastic instability are developed. The analytical solutions were validated by comparison with finite element simulations and burst tests on 3” diameter pipes. Two materials with very dissimilar plastic behavior, low carbon steel and austenitic stainless steel, were used on the experiments. Twenty-nine burst testes were carried out with pipe sections with axis-symmetric flaws and twelve were performed on pipe sections with narrow flaws. The analytical models for stress and strain agreed well with the numerical model, and both the analytical and the numerical predictions showed good correlation with the experimentally observed burst pressures.

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