Deepwater Subsea Pipeline Repair with Lightweight Remote Clamp

CASE STUDY

New Approach to Delivering Lightweight High-Pressure Remote Clamps

CSS Morgrip Deepwater Coating Removal Tool during the operation at 830 mwd

01 // CSS 4″ Deepwater Coating Removal Tool operation at 830 mwd

A MAJOR OPERATOR IN WESTERN AUSTRALIA EXPERIENCED A DEEPWATER PIPELINE FRACTURE WHICH REQUIRED AN URGENT REPAIR. THE OPERATOR COMMISSIONED CONNECTOR SUBSEA SOLUTIONS (CSS) TO DEVELOP A NEW CLAMP SOLUTION TO MEET THE SPECIFIC DEMANDS OF THE PROJECT.

The Challenge

At 830 mwd, a 4″ MEG line was found fractured—well beyond diver reach. With a 400 barg rating, any repair required a remote, high integrity clamp supported by DNV-GL Product Certification for subsea pipeline repair (F101/F113). Conventional heavy clamps and remote tension systems risked overstressing the small bore, so clamp weight became a critical constraint. Reliable sealing also depended on clean, damage-free surface preparation, so CSS deployed its Deepwater Coating Removal Tool to achieve a bare-metal finish and prepare the line for installation.

02 // CSS MORGRIP^® 4″ Deepwater Coating Removal Tool

“We reinvented how a remote clamp can be operated. Remote technology is often evolved from shallow-water applications. By developing a solution from the outset to address the unique challenge of deepwater, our solutions are simply more optimised. Lighter, more reliable and safer for the operation."

Pål Magne Hisdal

CSS Chairman

Connector Subsea Solutions (CSS) Coating Removal Inspection via ROV

03 // Coating removal inspection

Our Solution

Rather than adding more steel to the pipe, the engineering step was to take weight out of the clamp. All hydraulics, controls and test functions were moved into a retrievable unit that also serves as the installation frame. This lets the frame carry the handling loads during set-up, then lift away cleanly so only the sealed clamp body remains on the line. For a small-bore, high-pressure system at 830 m, that shift reduces pipe stress, simplifies handling, and removes unnecessary mass from the permanent repair.

The activation method was equally important. A single point C-Bar system replaced multiple remote tensioners, high-pressure feeds and auxiliary monitoring gear, giving precise, centralised control from one location. The clamp was built to DNV-GL Product Certification for the specific field conditions, while CSS’s Deepwater Coating Removal Tool—with a patented cutting head—prepared the surface to bare metal without harming the parent pipe. Together, the lighter architecture, controlled activation and verified surface preparation form a clear route to a high-integrity seal in deep water, with fewer variables to manage and a cleaner interface for inspection and testing.

Project Execution

Following extensive factory acceptance and system integration testing, including multiple pressure tests to exceed the 400 barg requirement, all equipment and tooling was mobilised.

The coating removal operation was conducted first, providing a bare
pipe onto which the clamp would seal. The clamp mounted in the installation frame was then deployed. Lowered directly onto the repair location, the frame supported the weight of the system during activation and testing. Upon completion, the frame disconnected and was retrieved to the vessel, leaving only the clamp as a permanent repair on the pipe.