Resistance of X80 Steel to Ductile-Crack Propagation in Major Gas Lines

摘要

The need for more efficient gas delivery has prompted corresponding research by large energy companies on topics such as the transportation of liquefied gas, the creation of generation capacity with the construction of high-tension dc transmission lines, and, of course, high-pressure gas pipelines. Undoubtedly, increasing the working pressure in the gas lines thanks to the use of high-strength steel capable of operating in complex climatic conditions is a promising approach. However, it is difficult to ensure the necessary combination of steel properties. For several decades, X70 steel of minimum yield point 485 MPa has been successfully used for major gas lines (diameter 1420 mm; working gas pressure up to 8.4 MPa). Recent designs, based on progress in steel and pipe production and in construction technology, have gradually increased the working pressure in new gas lines. Thus, the above-ground portion of the Northern European gas line is designed for a pressure of 9.8 MPa, with pipe of X70 strength class characterized by improved performance [1].