The design verification analysis and validation testing of an 8 inch jumper and integrated breakaway joint for the Stones subsea development located in 6,610 feet of water in the Gulf of Mexico is described. To control the jumper’s failure mode in the event of a pipeline anchor drag, the assembly was designed such that the maximum bending moment occurred at the location of the breakaway joint. The design and analysis investigated a series of U and M shaped jumper configurations and notched failure point geometries to achieve the desired objective.
Linearly-elastic finite element analysis was performed for a series of code check cases to ensure stresses in the jumper and breakaway joint due to normal in-service loads were below allowable values. Nonlinear elastic-plastic finite element analysis was performed to determine the capacity of the jumper and breakaway joint due to pipeline snag loads. The material properties for the nonlinear elastic-plastic analysis were based on tensile tests on specimens taken from prolongations on the actual breakaway joint forgings. The results of the analysis indicate the breakaway joint notch is the weak point in the final jumper configuration, with a moment capacity well below the rated capacity of the manifold connectors. The fatigue analysis concludes the design life of the breakaway joint is greater than that of the jumper assembly welds.
Validation tests were conducted to confirm the design of the jumper and breakaway joint. A pure bending test was performed on the breakaway joint and a full-scale test was performed on a portion of the jumper. A test fixture for the full size quarter-jumper pull test was modified to ensure enough stroke was available to fail the jumper sample in a single, continuous pull. Strain gauges, a data acquisition system, and video system were used to monitor and record the strains and displacements along the quarter-jumper test sample. Both tests demonstrated excellent agreement (96%) with the predicted analytical results obtained during the jumper assembly design phase.
San Pedro, R.I., Boubenider, R., Neelam, M.K., Walden, N.L., Epperson, D.R., “Design Verification and Validation Testing of the Stones Jumper Breakaway Joint,” Proceedings of the Offshore Technology Conference 2017 (OTC- 27571-MS), Houston, TX, May 1– 4, 2017.