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

Abstract

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 × 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 3LPP coating temperature for enhanced external collapse pressure as compared to the as-fabricated pipes. The strain gauges and deflection sensors were used to measure the external collapse pressure by ring method. The test results were compared with the values predicted by Linear-Elastic Thick Wall theory considering the plain strain behaviour and ABAQUS for Non-Linear Finite Element analysis to simulate the collapse pressure. 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 behaviour of pipe material.