FPSO topside transition joints and terminations – UK North Sea

Power CSL Scope

Design, supply and installation of I-tube mounted transition joints, topside jumper cables, and electrical terminations for a North Sea FPSO project.


A major UK oil operator required purpose designed transition joints to connect 3 subsea umbilicals, each containing 15 MV power cores to an FPSO electrical system. The joints needed to be mounted on I-tube hang-offs located in the FPSO Zone 1 rated FPSO manifold deck. Flexible MV jumper cables and terminations were required to run from the transition joint to a number of HV junction boxes. The area where the joints was to be installed was highly space constrained in terms of available area and headroom.

Power CSL Deliverables

  • Detailed design study including mechanical interface with I-tube, thermal FEA of the transition joint, verification of Zone 1 performance, MV jumper cable connections and termination design. Throughout this phase close liaison was required between PCSL, umbilical manufacturer, FPSO EPC, and the end Client project engineering functions.
  • Mock-up of manifold deck at PCSL workshop and timed trial assembly of transition joint in order to explore methods of minimising offshore installation time.
  • Supply of :
    • 3 transition joint kits
    • 45 MV pre-prepared flexible MV jumper cables
    • 45 MV special design terminations
  • Supply of 4 off PCSL offshore technicians and equipment for installation of products on the FPSO


All products were supplied and fitted to agreed schedule, with no problems encountered throughout the installation exercise.

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Products & Services

Power CSL provides a complete range of subsea cable and umbilical products and services – from factory jointing (splicing) of medium and high voltage power cores to thoroughly engineered and tested cable accessories including offshore repair joints.


Power CSL’s facilities at its headquarters in Kent, UK, includes impressively equipped cable jointing workshops, a dedicated high voltage laboratory and a wide range of analytical, mechanical, and hyperbaric test capabilities.