Experimental and numerical investigation of high-pressure water jetting effect toward NPS8 natural gas pipeline integrity-establishing safety distance perimeter

Abstract

Occasionally, gas distribution pipelines are laid in adjacent to water facility pipelines. Water pipelines' leakage poses a great danger through its release of high-pressure water jets that subsequently mix with solid particles to form erosive slurries. If the pressure from the jets is directed toward the metal pipe, this highly erosive form of slurry could dramatically erode the walls of the pipe, which may lead to its point of failure. This chapter will discuss the experimental and computational study of two piping failures involving the API 5L X42 natural gas pipes caused by high-pressure erosive slurries. An experimental study was conducted in an uniquely developed water jetting testing facility to simulate an underground natural gas pipe environment. A sandbox is used as the medium for the pipe and the sandbox is an important rig loaded with sand as the material representing the usual backfilling material for natural gas pipes. Due to the limited capability of the testing facility, the computational fluid dynamics (CFD) technique was employed to estimate the hydrodynamic characteristics, erosion patterns and to locate the ruptured locations on the pipe in a more expanded version. Studies on fluid velocity, wall shear, and total pressure generated on the surface of the natural gas pipe were also performed. Experimental and CFD simulation results show that the highest shear strain rate area coincides with the leakage points. The enhanced CFD simulation results show a similar trend with the rupture of the API 5L X42 natural gas pipe incidents, thus indicating the success of mutually agreed results of hydrodynamic characteristics.