Seabed, currents posed problems in Gibraltar pipelay
Installation of the twin submarine gas pipelines crossing the Strait of Gibraltar posed significant engineering and pipelay problems for lay contractor Saipem S.p.A. The rocky and highly irregular sea bottom created major pipelay problems and necessitated laying the pipelines with extreme precision and minimum tolerance. Further complicating the pipelay were the high surface and bottom currents which at times could reach up to 5 knots. Specifically, the rocky and irregular sea bed made mooring and anchoring the layer vessel Castoro Sei difficult. In addition, the operation had to resolve problems caused by vortex shedding during and after pipelay. Saipem modified the Castoro Sei by extending its pipelay ramp to a departure angle of up to 50{degree}. This modification decreased the pull on tensioners by 60 tons. This resulted in minimization of residual tension, which further resulted in the pipe following the seabed profile, and in a reduction in free-span lengths and height. This and other engineering approaches made possible completion of the pipelay in record time and with minimal seabed interventions. The paper describes critical areas of the route and a slight re-routing needed to avoid a World War II mine.
- OSTI ID:
- 404488
- Journal Information:
- Oil and Gas Journal, Journal Name: Oil and Gas Journal Journal Issue: 49 Vol. 94; ISSN 0030-1388; ISSN OIGJAV
- Country of Publication:
- United States
- Language:
- English
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