Feasibility of yield strength-based 100% SMYS pressure test of X80 steel pipes

High-strength pipeline pressure test is the general trend worldwide. To study the feasibility of 100% SMYS (minimum yield strength) pressure test for X80 steel pipes in China, taking the western pipeline section in Second West-to-East Gas Pipeline as an example, the probabilistic method is used to analyze the distribution characteristics of yield strength for samples of X80 straight seam steel pipe and spiral seam steel pipe, and the differences between physical yield strength and sample yield strength are studied. As is shown from the results, yield strength distribution for samples of X80 straight seam steel pipe and spiral seam steel pipe are consistent with normal distribution, X80 straight seam steel pipe is better than spiral seam steel pipe in the yield strength, and physical yield strength of steel pipe is 10% to 15% higher than small sample yield strength. For the base metal yield probability of less than 1% due to 100% SMYS pressure test, it is obtained that the X80 steel pipe can follow the 100% SMYS pressure test based on probability distribution characteristics of pipe sample yield strength and differences between sample and physical yield strengths.