Pipe Clamping Mattresses

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Step-change in arresting pipeline walking

Page last modified

April 11 2024

Developed by Subcon in cooperation with Shell Global Solutions (Shell), the engineered 'pipe clamping mattress' (PCM) is used to mitigate pipeline-walking.

With rock-dumping the vast majority of load is passed straight to the seabed, but with PCMs 100% of the load is effective in mobilizing axial resistance.

The technique was first developed on Shell's Malampaya Project; as an alternative to traditional rock dumping. Shell presented a technical paper on the Malampaya PCM’s at the Houston OTC available here

Pros & Limitations

Rock Dumping Alternative - Addressing pipeline-walking with PCMs rather than rock-dumping also eliminates the need for fall-pipe vessel and competent rock

Eliminates Suction Pile – using a ‘wait-and-see’ philosophy for pipeline walking, eliminates suction pile fabrication and installation | As pipeline-walking is an uncommon and slow process, remediation can be achieved using post-installed PCMs

Design Efficiency - With rock-dumping the vast majority of load is passed straight to the seabed but with PCMs 100% of the load is effective in mobilizing axial resistance

Intellectual Property - Shell has a US patent pending for the PCM, but has now released the PCM option to the market via a global licensing agreement with Subcon

Specification

Specification Title	Specification Description
Accuracy	Clamping tolerance ~1mm (client issued pipeline to make the mould).
Areas of Application	Pipeline Walking Mitigation or Rectification.
Installation	PCMs can be installed as a pair (with the log mat) thus halving the installation time.
Lifespan	50 years
Material	Fibre reinforced concrete with neoprene lining.
Modular design	PCMs are deployed in banks determined by total restraining capacity.
Patents	Shell has a US patent pending for the PCM, but has now released the PCM option to the market via a global licensing agreement with Subcon.
Response time	PCMs can be designed, fabricated and installed in circa 4 months (thereby suitable for a wait-and-see approached where pipeline walking is reacted to).