Marine Design/

Fixed Structures

Longitude’s experience with marine and off-shore fixed structures addresses the entire life cycle of an asset, from initial concept through to decommissioning.

Fixed Structure Marine Design

Our engineers have provided concept designs for jackets and topsides, installation engineering using heavy lift vessels or floatover, asset integrity assessments, and design and analysis for decommissioning.

The fixed structure design services that we provide are:

  • Quasi-Static or dynamic structural strength and fatigue analysis
  • Assets integrity assessments and life extensions
  • Heavy lift analysis
  • Modifications for decommissioning of oil platforms
  • Transportation and installation engineering
  • Concept jacket and topside engineering/structural design

Over the past years, Longitude has designed the installation of fixed platforms using floatover methods developed in-house, as well as lifted installations with a heavy-lift vessel, or even a jack-up drilling unit.

Well-versed in offshore jacket installation procedure, Longitude has worked with offshore platform designers to ensure that given platforms are suitable for the chosen transportation or installation method, crucially avoiding last-minute re-designs.

Installation & Decommissioning of Jacket Platforms & Topsides

Longitude has taken this knowledge of oil platform installation engineering to develop safe, effective engineering systems for decommissioning. These range from small platforms with 1,000 to 2,000 tonne topside weight, up to systems for removal of large platforms up to approximately 25,000 tonnes. As part of the oil platform decommissioning process, Longitude assesses what is needed to safely lift the topsides and if necessary to design temporary strengthening of the topsides.

Jacket & Topside Installation Assessment

Longitude’s ability to assess jacket and topsides strength during the temporary phases of installation and removal can also be applied to a fixed platform in service. Longitude has provided asset integrity engineering for fixed structures and their components – such as flare towers – to determine the residual strength and remaining fatigue life of an offshore fixed structure. We have experience in designing solutions if the strength or fatigue life is found to be inadequate. These services are offered as part of the through-life assessment of a fixed oil platform, or as part of a life extension program.