Staubli's COS 08 subsea mono-coupling system for match plates assembly.
Staubli, based in Faverge, France, is to launch a new quick-release subsea coupling at Offshore Europe. The company has been working on this technology for the past 10 years, initially with Elf, which led to another coupling system being deployed in Elf Norge's Lille Frigg oilfield in 1992.
The company's latest offering, the COS 08, permits subsea high pressure hydraulic connections between two modules in a turbid environment. The pressure-balanced coupling, made from super duplex stainless steel, is tailored for three different modes of operation - stab plate, diver operable or ROV mateable, with a nominal bore of 8mm and CV of 1.5.
The COS 08 is pressure balanced in both connected and disconnected positions, with the result that operation is not affected by water depth. Nor does working pressure (the system is rated up to 11,000 psi) cause any separation force. Average working water temperature range is 0-60degrees C.
A built-in channel allows pressures in the coupling to be balanced with the marine environment. The force needed for the connection (68 daN) is governed primarily by the resistance of the springs in the mobile sealing barrier. Required holding force is 57 daN. The coupling's external profile has been designed to avoid ingress of impurities into the hydraulic circuit.
The COS 08 was tested successfully in the Texas-based Deepstar program. Other subsea products from Staubli, available in stab plate or screw lock execution mode (but not requiring balanced pressure couplings) are a 4mm nominal bore (SPS 05) flush faced, non-spill system rated at 15,000 psi and an 8mm nominal bore (SPS 08) version rated at 5,100psi. These are also made from super duplex stainless steel.
Copyright 1997 Oil & Gas Journal. All Rights Reserved.