Experimental study of unstable crack propagation velocity for X80 pipeline steel

Abstract

Unstable crack propagation velocity following the failure of pipeline steel has always been a problem. In this study, differences between the existing unstable crack propagation calculation models were analysed, and the deficiencies within the crack propagation velocity models were overcome. The hardening coefficient and hardening index of the ductile material were considered, and a velocity model of unstable crack propagation of pipelines based on the Hutchinson‐Rice‐Rosengren (HRR) theory elastic‐plastic stress‐strain field and the displacement field was established. Consequently, the limit propagation velocity was obtained. In full‐scale burst test, the pipe with diameter of 1422 mm was chosen to simulate the natural gas pipeline transportation environment. Compared with the theoretical result, the error was limited in 13%. The research result solved the problem of quantifying the propagation velocity of the crack in X80 pipeline, which was significant for describing the forecast of velocity and length of unstable propagation and failure characteristics of pipelines.

Research on the fatigue properties of sub‐heat‐affected zones in X80 pipe

“…The increasing demand for oil and gas has prompted the extensive use of pipelines to transport oil and gas and stimulated the continuous development of high-strength pipeline steel with increased conveying efficiency. [1][2][3][4] Grade X80 pipeline steel has become the primary steel grade of pipeline transportation and has been used in the second and third lines of the West-East Gas Pipeline and the newly constructed gas pipeline from Russia to China through the Eastern route. [5][6][7] During long service, transmission pipelines are often affected by alternating stress caused by switching machines and internal pressure fluctuation.…”

Research on the fatigue properties of sub-HAZs in the X80 pipe

“…The increasing demand for oil and gas has prompted the use of pipelines to transport oil and gas and stimulated the continuous development of high-strength pipeline steel to increase conveying efficiency [1][2][3][4] . Grade X80 pipeline steel has become the primary steel grade of pipeline transportation, such as in the second and third lines of the West-East Gas Pipeline and the newly constructed Gas Pipeline from Russia to China through the Eastern route [5][6][7] .…”