The opening and sealing of existing deepwater pipelines pose a range of challenges, such as fully mechanised repair work beyond human diving depths, pipelines normally not being prepared for mechanical attachments, with no flanges or hubs to mate with, or pipe walls having limited strength, which may impose limitations on the attachment.
A DNV Recommended Practice that will be a part of the OS-F101 "Submarine Pipeline Systems" will be issued in 2006, providing acceptance criteria and state-of-the-art documentation of proven technology and sound engineering practices. The Recommended Practice will focus on prioritized issues identified by the industry. "One of this project's main challenges is to prepare a level technical basis for specifications, design and acceptance criteria and testing," says DNV's project manager Tore Mellem.
Back in 1998, DNV managed a similar project called "Mechanical Pipeline Couplings". This led to a Recommended Practice document relating to the development of a remotely operated pipeline repair and tie-in system for a full range of pipeline dimensions, including pipelines below diving depth. However, some aspects of that document, as well as the need to also cover clamps, plugs, hot-tap and welded sleeves, called for a new revision, and work has today been started to meet this need.
The technical areas to be covered by this project are:
Participants are BSPC/Gazprom, Dong, ENI Gas&Power, Medgaz, Hydro, Shell Norway and Statoil. DNV's knowledge and experience combined with that of these partners will ensure a reliable, practical and user-friendly Recommended Practice.
"This team will provide a good basis for acceptance throughout the industry of the new Recommended Practice, which will be practical, useful and adoptable," says Tore Mellem.
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