CRA冶金复合海底管道整体屈曲大应变腐蚀疲劳设计

Fatigue Design of CRA Clad Pipeline Under Cyclic Global Buckling with Large Strain in Corrosive Environment

针对高温高压、高含硫、强酸性环境中发生大应变整体屈曲的耐腐蚀合金(Corrosion Resistant Alloy,CRA)冶金复合管道,通过酸性环境腐蚀疲劳试验建立CRA冶金复合管道酸性介质环境耐久性疲劳折减因数和疲劳裂纹扩展速率Paris公式,用于海底管道循环屈曲情况下的大应变腐蚀疲劳设计,包括S-N疲劳校核及基于断裂力学的裂纹扩展疲劳校核,即ECA评估。通过ECA评估确立适用于本项目CRA冶金复合管道环焊缝全自动超声波检测(Automatic Ultrosonic Testing,AUT)的验收标准,可为类似项目提供借鉴。

The Corrosion Resistant Alloy(CRA)clad pipelines under cyclic global buckling with large strain in high temperature high pressure,high sulphur content and strong acid corrosive environment is focused on.A series of fatigue testing of the CRA clad pipeline girth weld under acid corrosive environment are carried out to establish the fatigue knock-down factor of the fatigue endurance S-N curve and the fatigue crack propagation Paris law in acid environment.Based on the parameters obtained from the testing,both S-N fatigue check based on stress and crack propagation fatigue assessment based on Engineering Criticality Assessment(ECA)method are performed to confirm the integrity of the CRA clad pipelines with high temperature high pressure going through cyclic global buckling.Through project specific ECA,the Automatic Ultrosonic Testing(AUT)acceptance criteria for automated ultrasonic testing of girth welds is established for CRA clad pipeline.The design process demonstrated can provide guidance for similar offshore pipeline project.