23C Conductor Removal and Decommissioning
North Sea
Technicus Consulting were appointed by Perenco UK to provide independent structural verification and engineering consultancy services for a proposed conductor removal hoist assembly on the 23C offshore platform.
The lifting assembly comprised 2No 13m long runway beams spanning between the primary trusses of the 23C platform. The runway beams support a hoist trolley and lifting assembly with a 100te SWL, which is used to withdraw the conductor pipes.
The hoist assembly and runway beams were designed by the supplier, and Perenco UK appointed Technicus Consulting to undertake an engineering review of the design, and to assess the adequacy of the 23C primary truss structures to support the lifting assembly reactions.
As part of the design review adjustments to the lifting assembly were made and additional bracing was installed to provide lateral stability to the runway beams during withdrawal operations.
Calculations & 3D analysis models were produced to assess the capacity of the platform structure. These showed that the primary framing was capable of supporting the lifting forces, thus allowing the proposed conductor decommissioning to proceed.
