A preliminary investigation of the effects of environmentally assisted cracking on natural gas transmission pipelines

Abstract

Concepts for the development of a model to predict natural gas transmission pipeline lifetime in a corrosive environment are constructed. Primarily, the effects of environmentally assisted cracking (EAC) are explored. Tensile test specimens from a sample of API 5L X-52 pipeline were tested in a simulated groundwater solution and subsequently analyzed. The results suggested that the simulated environment ultimately reduced the ductility of the test specimens; however, no evidence of ??classical?? stress corrosion crack morphology was discovered. However, corrosion pits up to 0.75 mm (0.03 in) were revealed during metallographic analysis. A Marin factor analogy and an energy method concept are suggested and explored. Ultimately, the test data set was too small for the results to be of any directly applicable significance.