Acteon company CAPE Group, based in Singapore, has developed and successfully tested an orbital welding unit that can be used to repair oil and gas pipelines on the seabed.
A trial was carried out in Abu Dhabi recently when two sections of 30-in. pipe were successfully welded underwater within a hyperbaric chamber specially designed to house the orbital welding equipment. The results of X-ray analysis and mechanical testing of the weld have since all proved perfectly satisfactory.
As a result of this first trial, plans are being made to carry out further tests later this year on 48-in pipeline to prequalify the technique for pipeline repairs for two major Qatar-based operators.
Much of the work to develop the welding unit was carried out in a dry pressure chamber, owned by CAPE Group and located in Abu Dhabi. The chamber, which is capable of simulating water depths to 600 ft, will be used in future to define welding procedures and qualify the welding unit to meet the pipeline repair requirements presented by individual clients.
Simon Hartog, managing director of CAPE Group, said, "The success of the recent trials and the interest now being expressed in the unit by several important players in the Middle East is reward not only for the effort we have put into its development over the past 12 months but also our considerable financial commitment. There have been previous attempts within the offshore industry to introduce underwater orbital welding systems but to the best of our knowledge this is the world's first genuinely commercial unit."
Despite advances in mechanical pipeline repair systems, welding still has an important role to play in certain circumstances. It is obviously the method of choice when operators want to return a damaged pipeline to its as-designed state. Welding is also the key to the repair of internally clad, sour-service lines, as there are no available mechanical flange fittings capable of adequately sealing the interface between the main pipe and the internal cladding. Welding, however, has generally required pipelines to be lifted from the sea in order to achieve acceptable results. The welding of critical components manually within underwater hyperbaric chambers has not proved popular for cost and quality reasons, and because of the lack of adequately trained and qualified diver-welders. And no company, at least until now, appears to have successfully overcome the practical challenges of transferring the far better (automated) orbital technology into the subsea environment -- or at least no company has succeeded in doing it economically.
TOPS Offering Expanded
The CAPE Group believes it has the first commercial welding solution to the problem of repairing pipelines on the seabed. "The ability to weld underwater with confidence significantly expands our Total Oilfield Pipeline Solutions (TOPS) offer, which was previously limited to mechanical repair and maintenance technologies," said Hartog. "We are excited by the prospects for this equipment not only in the Middle East but further afield. It provides our customers with a valuable option when faced with a leaking or damaged pipeline."
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