Multiaxial Fatigue Analysis on Reeled Deepwater Steel Catenary Risers with Girth Weld Defects

• Published in: China ocean engineering Vol. 28; no. 6; pp. 857 - 868
• Main Author: 杨和振 丁金鸿 李清泉 李华军
• Format: Journal Article
• Language: English
• Published: Heidelberg Chinese Ocean Engineering Society 01.12.2014
• Subjects: Catenaries; Coastal Sciences; Engineering; Fatigue (materials); Fatigue life; Finite element method; Fluid- and Aerodynamics; Marine; Marine & Freshwater Sciences; Mathematical analysis; Numerical and Computational Physics; Oceanography; Offshore Engineering; Risers; Simulation; Weld defects; 多轴; 安装过程; 悬链线; 有限元分析; 深水; 焊缝缺陷; 疲劳分析; 立管; pipeline; weld defect; installation; multiaxial fatigue; steel catenary riser; deepwater; reel-lay
• ISSN: 0890-5487; 2191-8945
• DOI: 10.1007/s13344-014-0066-8

In the present study, we simulated the reel-lay installation process of deepwater steel catenary risers（SCRs） using the finite element method and proposed multiaxial fatigue analysis for reeled SCRs. The reel-lay method is one of the most efficient and economical pipeline installation methods. However, material properties of reeled risers may change, especially in the weld zone, which can affect the fatigue performance. Applying finite element analysis（FEA）, we simulated an installation load history through the reel, aligner, and straightener and analyzed the property variations. The impact of weld defects during the installation process, lack of penetration and lack of fusion, was also discussed. Based on the FEA results, we used the Brown-Miller criterion combined with the critical plane approach to predict the fatigue life of reeled and non-reeled models. The results indicated that a weld defect has a significant influence on the material properties of a riser, and the reel-lay method can significantly reduce the fatigue life of SCRs. The analysis conclusion can help designers understand the mechanical performance of welds during reel-lay installation.