A Novel Design of Retrofit Hang-off Structure For Steel Catenary Risers

A novel design of retrofit hang-off structure that was used to tie-back Steel Catenary Risers (SCRs) to a jacket platform is presented. The structure includes baskets, tubular support members, hang-off clamp and stop clamp. The structure possesses two novel features: dual clamp redundancy and tubular members to support baskets. Though the clamp is designed as a friction clamp to withstand all operational and extreme loading from the SCRs, a Stop Clamp is provided below it for dual redundancy in case an unlikely loss of friction occurred at the SCR Clamp. The Stop Clamp is supported by the jacket bracing members through saddle supports. The Stop Clamp is designed to assist in the proper orientation of the SCR clamp during installation. Different from the conventional I-shaped bracing members, tubular bracing members are used to support the baskets. This approach reduces the welding requirements and steel material usage significantly. A variety of analyses were performed to ensure that the design of the structure is adequate to perform the targeted service.