For this project, we were commissioned to manufacture a J-tube with riser for the D15-A jacket. These items are a part of the landing of the pipeline and umbilical. The scope of the project also included the tie-in of the pipeline to the platform and modifications to the platform, as well as the new platform extension, piping and supports to be manufactured and installed. All work was for the D12-B silimanite project.

Due to the exotic material used for the piping in the project, welding qualifications were required to show that we have the knowledge and skills to perform the welding work. Planning was crucial due to the scope and various subcontractors being used. During the project, it was adjusted once and then the total scope was accomplished according to the new schedule.

Scope of the project

  • Manufacturing of a J-tube
  • Manufacturing of a riser
  • Manufacturing of multiple welded clamps between the J-tube and riser
  • Manufacturing of several welded clamps between the J-tube and jacket
  • Manufacturing of two subsea spools
  • Manufacturing of two backbone constructions for installation of subsea spools
  • Manufacturing and installation of a platform extension for the J-tube
  • Manufacturing and installation of platform modifications
  • Manufacturing and installation of a platform riser clamp
  • Manufacturing and installation of 26 platform spools and 19 platform supports
  • Performance of trail-lifts to determine center of gravity.
  • Delivery of documentation in cooperation with various inspection authorities.
  • Purchase of materials, work preparation, planning, manufacturing and installation
  • Non-destructive testing of welds and lifting points, hydrostatic testing, wrapping, vulcanization of clamps, internal/external preservation, nitrogen testing, anode continuity testing, lifting tools and trial-lifts, loadout to floating pontoon and final transport to boat (by pontoon and truck)


  • Type of assignment:Construction
  • Onshore or offshore:Onshore and offshore
  • Platform: D15-A
  • Location: North Sea
  • Contractor: Neptune Energy
  • Contractor: Multimetaal

Project team and supervision

  • Project leader Martijn Vacano
  • Multimetaal personnel
  • Various subcontractors for specialist work (such as testing, preservation, vulcanization and wrapping)