For design of pipelines for transportation of harsh corrosive fluids or for reassessment of pipelines in use, imperfections such as corrosion defect need to be included in the strength calculations. One of the Limit States that often dictates offshore pipeline design is local buckling. If in-place analyses predict that the maximum allowable moment to a pipeline will be exceeded, it will be necessary to either increase the wall thickness or, more conventionally, to perform seabed intervention to reduce the bending of the pipe. The normal approach for including corrosion defect in the strength calculations has been to use the estimated or measured minimum wall thickness as the nominal wall thickness in the strength calculations. In this paper the bending moment capacity for groove corroded metallic pipes has been investigated with the intention of optimising the cost effectiveness in seabed intervention design without compromising the safety of the pipe. The focus has been on how to account for the interaction between pressure, longitudinal force and bending in the bending moment capacity calculations of groove corroded pipes. The study is based on an analytical approach which accuracy has been verified against the finite element method and laboratory tests. The result of this study is a set of equations for calculating the maximum allowable bending moment including proposed safety factors for different target safety levels. The maximum allowable moment is given as a function of initial out-of-roundness, corrosion depth, width and length together with longitudinal force and internal/external overpressure. The equations can be used for materials with isotropic as well as an-isotropic stress/strain characteristics in the longitudinal and hoop direction. The analytical approach given herein may also be used for metallic risers and pipes in structures if the safety factors are calibrated against appropriate target safety levels.

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