Design and Installation of Auger Steel Catenary Risers

Phifer, E.H.; Kopp, Frans; Swanson, R.C.; Allen, D.W.; Langner, C.G.; ,

Design and Installation of Auger Steel Catenary Risers

by E.H. Phifer, Shell Development Co,
Frans Kopp, Shell Oil Co.,
R.C. Swanson, Shell Development Co.,
D.W. Allen, Shell Development Co.,
C.G. Langner, Shell Development Co.,

Part of: Offshore Technology in Civil Engineering: Hall of Fame Papers from the Early Years

Abstract:

The Auger export pipelines are connected to the TLP by steel catenary risers (SCRs). This is believed to be the first time steel pipe has been used for catenary risers. SCRs offer advantages over tensioned risers, since SCRs need no heave compensation and no subsea connections, and over risers made of flexible pipe, since SCRs are much less expensive. However, significant design effort was required to prove that the SCRs could safely withstand environmental loads and the effects of TLP motions. The design effort consisted of extensive dynamic analyses as well as full scale fatigue testing of both the riser joint welds and the flexible joint that connects the riser to the TLP pontoon. Devices which suppress vortex induced vibrations were also tested. SCR installation is accomplished by lowering the riser on the abandonment and recovery cable from the J-Lay installation vessel and transferring the riser on a chain that is run through a chain jack hung from the TLP upper deck structure. A special Installation and Maintenance System was built for this purpose.

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