Subsea Pipe Support – Remediation

The Scope

Cube Offshore were approached by WEL directly to resolve a problem relating to an existing subsea spool support structure @ (-)820m whereby the support structures needed to be extended in length.  The solution involved concept screening, development, manufacture and full scale testing of 2 x Support Beam Extension and Mudmat Frame assemblies to be retrospectively attached to the existing subsea structures.  The schedule was extremely tight with delivery required only 10 weeks from the first discussions to coincide with construction vessel availability.

The Outcome

Cube Offshore collaborated internally at Woodside to achieve multiple stakeholder approvals and externally to bring together small specialised local service providers to deliver a high quality, multi-discipline product.  Cube Offshore delivered the structural/mechanical engineering and project managed the externally supplied geotechnical, cathodic protection, ROV, precision machining, steel fabrication and load testing.  The schedule was extremely tight therefore the equipment was delivered and installed in two stages.  The first  stage was to deliver & install the 2 x Beam Extension components by the 10 week deadline thereby meeting the initial vessel availability and temporarily mitigating the subsea problem.  A later (8 weeks) installation window was identified and utilised for delivering & installing the 2 x Beam Extension supporting Mudmat Frames thereby making the solution permanent.

The equipment was delivered on time and exceeded the original temporary specifications with a robust long term solution.  Installation was achieved safely and without hitch.


3D image of the Beam Extension and Mudmat Frame installed onto the existing subsea pipe support


FEA of new Beam Extension connected to existing pipe support

FEA of connecting “wedge” arrangement at end of Beam Extension


FEA assessment of existing pipe support foundation


Beam Extension detail

Beam Extension load test set up during SIT.

Simultaneous 10t vertical + 4t horizontal (pull out) applied.


2 x Beam Extensions ready for delivery

2 x Mudmat Frames ready for delivery

Excerpts from Beam Extension installation procedures


Excerpts from Beam Extension installation procedures