Project Background

When an international operator in West Africa requested
an Emergency Pipeline Repair System (EPRS) clamp for their
10″ PiP production line, CSS engineered a bespoke design
tailored to PiP-specific repair scenarios, accommodating
varying nominal pipe sizes whilst remaining simple enough
to enable fully diverless installation.

The PiP clamp supplied was engineered to seal a leak on
the inner pipe, including at a field joint location where the
minimum available clearance occurs. It seats securely on the
inner pipe within the minimal annular clearance of a standard
field joint, ensuring sufficient clearance to the outer pipe
even when accounting for nominal OD variations.

Key Challenges

1. PiP Geometry: The two concentric pipes left very little clearance at the field joint. The clamp therefore needed to avoid contact with the outer pipe yet still seal fully on the inner pipe.
2. Inner-Pipe Variations: Two nominal OD variants necessitated a seal that could accommodate a range of diameters without compromising performance.
3. Deepwater, Diverless Requirement: The project’s deepwater environment necessitated deployment and activation entirely by ROV.
4. High Operating Pressure: At 317 barg, any leak could rapidly escalate. The clamp therefore needed to be rated well above this pressure to provide operator confidence.

Engineering Solutions

During a front-end engineering design (FEED) study, CSS
evaluated several PiP repair concepts to address different
potential failure modes, covering inner and outer pipe failures
at field joints and along the main pipeline. Ultimately, the client
opted for a streamlined clamp focused entirely on the inner pipe
to provide contingency for the most likely failure scenarios.

Key features include:

• Slim Profile Body: Compact external dimensions allow
  the clamp to slide into the narrow annular gap without
  contacting the outer pipe. Small buoyancy elements were
  added to ensure the clamp remains correctly oriented once
  activated, allowing the crane to disengage smoothly.
  
• Adjustable Landing Saddles: Saddles can be fine-tuned to
  accommodate landing installation tooling on the inner or
  outer pipe, ensuring a precise fit at the field joint or another
  specified location.
  
• Diverless ROV Guide Tooling: Instead of gripping the pipe
  directly, the installation tooling was designed to gently
  guide the clamp along the field-joint ribs. Once in position,
  hydraulic lines would close the clamp around the inner
  pipe. After activation, the lines would be cut, allowing the
  tooling to float to be recovered.
  
• Material Selection: The clamp body was forged from F60,
  selected for its superior strength and corrosion resistance
  in deepwater environments.

02 // CSS MORGRIP^® PiP Clamp undergoing hydrotest during FAT

03 // CSS MORGRIP^® PiP Clamp including installation tooling

04 // CSS MORGRIP^® PiP Clamp including installation tooling

05 // CSS MORGRIP® PiP Clamp with bolt deployment basket

Delivery & Contingency Stock

Once fabrication and testing were complete, the clamps were
shipped to the client. They now form part of the EPRS inventory,
ready for immediate deployment should a pipe leak occur.

Conclusion & Customer Feedback

By engineering a specialised PiP clamp, CSS delivered an optimised and cost effective contingency solution for the client’s high criticality pipeline. Its simplicity reduces manufacturing and maintenance costs, while the diverless installation tooling ensures reliable deepwater deployment. In practice, this lowers operational risk and gives the operator confidence that, should a leak occur, a proven clamp is ready for immediate use anywhere along the PiP system.