Design Verification Analysis for a Subsea External Tieback Connector Bending Capacity Using API 17TR8 Criteria

The objectives of this paper are to determine the structural and functional bending capacity, for an 18-3/4 inch 10 ksi Dry Completion Unit (DCU) external tieback connector (ETBC), utilizing more advanced analysis design verification procedures of API 17TR8 [1]. This requires the evaluation using a 3D nonlinear elastic-plastic finite element analysis (FEA). Although the design verification procedures of API 17TR8 [1] are written for high pressure high temperature (HPHT) equipment, this paper demonstrates the feasibility of applying it to lower pressure equipment which have more critical requirements for bending capacity vs. pressure capacity. The capacity results are compared between the existing linear elastic criteria of API 17G [2] and the requirements of API 17TR8 [1]. The application of this evaluation demonstrates that the analysis methodology for HPHT equipment can be applied to subsea tieback connectors to obtain maximum bending capacity of the connection.