November 2008 saw the first deliveries of Techlok clamp connectors from Vector International, the pressure connection and sealing specialist, to Samsung Heavy Industries to be used to provide reliable leak-free pipe connections with minimal weight implications on the Skarv FPSO, being constructed in South Korea for BP Norway on behalf of the Skarv Idun Unit.
The Techlok clamp connectors, manufactured in carbon steel duplex and more exotic nickel alloy 708, range in size from six to 26 inches. They will be used extensively on the FPSO on flow lines, oil export lines, gas injection lines, chemical injection lines, corrosion inhibitor lines, and on the topside of the vessel, operating at pressures from 2,250 to 6,250 psi.
Techlok clamp connectors provide a high performance, no-leak alternative to traditional ANSI flanges, offering weight and space savings of typically 70-80 per cent over conventional connection methods, coupled with significantly improved joint integrity.
Space and weight savings are particularly important on an FPSO. A 2500 class 12 inch Techlok connector weighs some 263 kg, as against 1568 kg for the equivalent rated ANSI flange – a substantial saving of more than 80%. In total, the 800 Techlok connectors being used on the Skarv FPSO amount to a massive and valuable total weight saving of some 70,000 kgs, compared to the equivalent pressure-rated ANSI flanges.
Additionally, the Techlok clamp connectors provide reliable, leak-free performance. Unlike an ANSI flange, the Techlok uses a pressure-energized metal-to-metal seal which does not rely on bolting to maintain seal integrity (the bolts are transversely mounted and almost entirely isolated from the operating loads). On installation, the hubs are drawn together as the four bolts are tightened to close the clamp segments and compress the sealring, which makes the first stage seal. Once in service, the internal pressure reinforces this seal.
The Techlok clamp connector can withstand high tensile loads and severe bending loads, and still retain full joint integrity, with the ability to withstand pressures in excess of 30,000 psi. It can also withstand extreme temperatures. On this project, some of the Techlok joints are required to be able to operate at temperatures as low as minus 130 degrees C.
A further benefit of the Techlok clamp connector in this construction project is the reduced bolting requirement (just four bolts per connector), making the joints considerably faster to make up. “Typically, several Techlok connectors can be made up in the time it would take to construct one ANSI flange,” Vector’s Director of Customer Services, Christopher Lee, points out. He goes on to add “Vector has again demonstrated that it can deliver to prestigious projects on time and to the specification and costs, utilising first class project management”
The project is also an example of Vector’s ability to work closely in partnership with its customers, applying its technical and engineering expertise to develop the optimum sealing solution. Vector worked closely with the project engineering contractor Aker Kvaerner in Norway, and construction contractor Samsung Heavy Industries in Korea, to develop the specification.
The Skarv and Idun development in the Norwegian Sea, in water depths of 350-450 metres, consists of the Skarv gas and oil field and the Idun gas field, and will be jointly developed using the FPSO, subsea wells, and an 80km gas export pipeline connecting to Asgard Transport System, with the oil exported via tanker.
The large Skarv FPSO vessel is some 292 metres long, with a breadth of 50.6 metres, depth of 29 metres, and hull weight (including living quarters, accommodating 100 persons in single cabins) of 40,600 tonnes. The hull, being built by Samsung Heavy Industries, will be delivered in January 2010. The FPSO is due to be completed in Korea by November 2010 and installed on location by March 2011.
