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Diverless pipe tie-in system trial completed

Jan. 5, 1998

The first offshore trial of a new diverless flange assembly system for offshore pipeline tie-ins has been completed successfully in U.K. North Sea Mallard field, under development by Shell U.K. Exploration & Production. Hydra-Tight Ltd. of Darlaston, U.K., claims its modular advanced tie-in system (Matis) will save offshore industry millions of dollars on tie-ins and will allow more cost-effective exploitation of deep water fields.

This photo shows how the Matis diverless tie-in system's tooling fits as a module within the installation frame. Photo courtesy of Hydra-Tight.

Hydra-Tight Ltd. of Darlaston, U.K., claims its modular advanced tie-in system (Matis) will save offshore industry millions of dollars on tie-ins and will allow more cost-effective exploitation of deep water fields.

Mallard is being developed as a subsea satellite of Shell's Kittiwake platform (OGJ, Oct. 28, 1996, p. 29). A Matis system was used recently to tie in two 8-in., 1,500-lb rated flanges.

The system was used to align the pipes in three spatial dimensions before tensioning the fixing bolts hydraulically.

Advantages

Hydra-Tight says the unit can be attached to a superclass remotely operated vehicle (ROV) for deepwater work: "Significantly, it offers subsea engineers the opportunity to return to the flange as a deep water connection method."

For shallow-water work, where it is reckoned to save up to 20% of the cost of conventional flange assembly methods, it can be deployed by an ROV, crane barge, drilling rig, or diving support vessel.

Hydra-Tight developed the system's tooling, comprising a carousel preloaded with stud bolts and a bolt tensioning system. The flange installation frame was developed by Stolt Comex Seaway Ltd., Aberdeen. Matis is designed for operation in up to 1,500 m of water, with any diameter pipe and either rigid or flexible spools.