L51979 Gas Decompression Behavior Following the Rupture of High Pressure Pipelines-Phase 1

The ability to predict the behavior of a crack propagating in a steel natural gas transmission pipeline is of great importance. This is because a long-running fracture is costly, both in terms of the time taken for replacement, and associated lost revenue, and the cost of replacement of the pipe itself. The determination of ductile shear fracture arrest toughness levels requires an accurate knowledge of the gas decompression behavior following the rupture. In particular, there is a need to predict accurately the gas decompression wave velocity within the pipe as a function of initial pressure, temperature and gas composition. Although models developed in the 1970's have proved remarkably robust to date, even when stretched considerably beyond their range of validation, operational characteristics currently being considered range far beyond any that have been investigated on a realistic scale. There is, therefore, a need to produce a model that has been validated for conditions relevant to next generation pipeline projects.

This report describes the work carried out in Phase 1 of a project to produce such a model. In Phase 1 a review of current knowledge was carried out and the work required in Phase 2 of the project was specified. This report describes Phase 1 of the gas decompression project. The aim of Phase 1 was to review the current state of knowledge on pipeline decompression. Carrying out this work has enabled the requirements for the model, the extent of validation that will be required and the proposed technical approach to be identified.