The first diverless system for assembling and undoing ANSI and API bolt flange joints on subsea pipelines is being tested in the U.K.
Called Atlantis, the system was developed by Hydratight Ltd., Wolverhampton, U.K., and Aberdeen-based Stolt Comex Seaway SA and National Hyperbaric Centre.
Atlantis is deployed with a remotely operated vehicle (ROV) and is designed to operate in waters as deep as 1,500 m.
The system is currently equipped for use on 6-24-in. diameter pipelines, but the partners have been asked to evaluate the possibility of using it on pipelines as big as 42 in.
The developers claim Atlantis will save as much as 20% of the cost of conventional flange assembly methods. It is expected to finish trials and be ready for market in fall 1997.
The unit consists of two sections, a carousel loaded with stud bolts and a bolt tensioning system. These are mounted in frames equipped with hydraulic actuators to align the tool to the flange.
Atlantis is mounted on the tool skid of a work class ROV, which locates the pipeline on the seabed and positions the tool astride the joint. Atlantis then grips the pipe and inserts and tensions the bolts.
Atlantis completed its first sea trial in shallow water near Birkenhead on U.K.'s west coast. It is currently undergoing pressure tests at the Hyperbaric Centre and will undergo further sea trials at the Stolt Comex complex near Dundee, Scotland.
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