Research on Development and Test Analysis of Full-Scale Fatigue Test System of X65 Submarine Pipeline

Abstract

The fatigue performance of welded joints of submarine pipelines is directly related to the safety and economic benefits of welded structures. Considering the limitations of fatigue calculation, anti-fatigue design and small-scale fatigue test in the evaluation and analysis of pipeline fatigue life, this paper demonstrated the feasibility, scientificity and advancement of submarine pipeline full-scale fatigue test technology in engineering applications. Consequently, a full-scale fatigue test system and its test analysis technology applied for ZY-PFS2000 pipelines have been first developed in China, in which the effects of welding residual stress, stress concentration, initial welding defects, pipeline internal pressure shutdown and internal medium fluctuations on the fatigue life of full-scale pipelines were comprehensively taken into account. Through the full-scale fatigue test (four-point bending + internal pressure) of the X65 submarine pipeline, the fatigue cycles of different specifications of pipelines under different stress amplitudes were obtained. Moreover, the fatigue loading results were evaluated and analyzed in accordance with the international standard of BS 7608 and DNV C203. The research in this paper is conducive to accumulating full-scale fatigue performance data for submarine pipelines in China, not only offering a quantitative basis for the subsequent full-scale fatigue life evaluation and the safety operation cycle, but also providing a reference direction for the future development of submarine pipeline full-scale fatigue test technology.