The J-integral Computation And The Safe Assessment Of X56 Pipeline With Surface Crack

As a kind of engineering structure, the submarineline has the abroad and important applications, which always is used to deliver the oil and the gas. At the same time, as a kind of welded structure, the welded joint of the pipeline always has the inevitable welding defects.With the development of the engineering practice, people gradually use the principle of the"fitness for use"to assess the influence of the welding defects on the structures, and don't required that the structure should not contain any welding defects. This movement not only take into account of the economic cost of the structure, but also provide the stable theoretical basis and experimental verification for the safe performance of the structure.This paper uses the principle of the"fitness for use"and the regulation of the SINTAP(Structural Integrity Assessment Procedure) to make an engineering critical assessment(ECA) for the submarineline which is developed by the COOEC and is located between Lvshun and Dalian.To finish the assessment, at first, we understand the regulations and the theories of the SINTAP. Then, we obtain the tensile property of the X56 pipe and the weld by performing the tensile testing of the weld metal and the X56 pipe and obtain the fracture toughness of the HAZ and the weld metal by determining the J-R cure of them. After that , we make with CDF drawing by interrelated formula and simulate the model of X56 pipeline with surface crack by finite element software ANSYS, then, we compute J integral of crack tip . After that , we perform the fifth level of SINTAP assessment to pipeline which has fixed surface crack size by CDF drawing. Relativing primary assessment, conservatism is reduced, and embodiments the principle of the"fitness for use", which offer the basis for the check and accept of the welding defect when the joint is detected by the NDT...