Hereema Marine Contractors

Scope of Work

BP Angola were developing a number of fields in offshore Angola on a four-project programme, as part of the first programme – Block 31 Development Programme, there was a requirement to cut the Production and Gas Lift Risers utilising cold cutting technology and the subsequent removal the polypropylene coating which was to be performed by Hereema Marine Contractors.

NRC were contracted to provide manpower and equipment for the removal of existing field joint coating using Ultra High-Pressure Water Jetting Cold Cutting application and Vacuum Transfer Technology.

Technical Challenge

To devise a cutting method which safely, effectively and efficiently removed the coating (layer of composite material – polypropylene), whilst simultaneously allowing extraction of the coating utilising vacuum transfer technology to prevent damaging the flow line.

Restrictions / Considerations:

• Under no circumstances could we, when removing the composite, make even the slightest “cut” into the actual flow line sections
• Critical Path Timeline
• The humidity in the work area during the operations reached 45 degrees at times, so it was crucial our operative’s welfare was taken into account during the “Project-planning” regimes

Key Facts

• Project completed in a controlled and professional manner without safety or environmental incident
• Commendations received from the client
• Success of the engineered cutting solution

Additional Information

The project was completed in two phases:

Phase 1 was effectively the development phase which involved the engineering phase, onshore trials /demonstrations and training of 2 HMC Personnel at the NRC facility in Aberdeenshire.

Phase 2 was the live operations, offshore in Angola the Balder (a Deepwater Construction Vessel capable of a tandem lift of 6,300 t, operated by Heerema Marine Contractors) to cut the sections of the composite, exposing the welds for NDT inspection, remedial repairs and re-coating by HMC.