Collapse Behaviour of As-FabricatedThermal Aged JCOE Line Pipe- Experimental Study by External Pressure Ring Collapse Testing and FE Analysis

摘要

This paper presents the experiments and studies conducted on pipes for the assessment of Middle East to India Deepwater Pipeline(MEIDP)requirement.The MEIDP will be located in water depths up to 3500 m and consequently be subjected to very high external pressures which make the pipe collapse strength a major consideration for the project.The pipes of size 660.4 mm(26”)OD x 37.1 mm WT and SAWL485 FDU manufactured by JCOE process were used for external pressure ring collapse testing in as-fabricated(AF)and thermal aged(HT)conditions.The simulation of ring collapse pressure using Finite Element Analysis(FEA)was also studied. The ring pressure collapse test results consistently demonstrated the advantage of heat soaked treatment at 3LLP coating temperature for enhanced external collapse pressure as compared to the as-fabricated pipes.A comparative study of ring collapse pressure testing,FE analyzed collapse pressure and DNV calculated collapse pressure is also presented along with tensile and compression behavior of pipe material.External ring collapse test facility developed in-house can be used to predict the collapse behavior and to simulate full scale collapse test.Finite element analysis was in agreement with the experiments and indicated all 3 modes of buckling both in as-fabricated and coating simulated rings.Out of Roundness (OoR)measurement was performed using caliper gauge by manual methods and by optical measurement system(OMS) system.The Out of Roundness as measured by OMS was slightly higher even after subtracting the peaking effect. KRing Collapse Pressure;; JCOE;; Thermal Cycle&Heat Treatment Simulation;; Plastic Collapse Pressure;; Linear-Elastic Theory;; Finite Element Analysis