Pipe Clamping Mattresses

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Step-change in arresting pipeline walking

Page last modified

August 4 2023

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

Pro/con

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

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).