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North Sea sub-sea contract for SFIL

19 December 2012

SHEFFIELD Forgemasters has secured a multi-million pound contract for crucial components to upgrade a sub-sea structure at the Siri oil platform in the middle of the North Sea.

The main work is for a 114-tonne clamp casting for the Siri Caisson Permanent Support project on the Danish continental shelf.

The six metre long and 2.8 metre radius casting is a crucial part of the new substructure. Forgemasters’ casting is part of the clamp connection to the existing substructure which will be braced to offer a permanent engineering solution

In addition to the clamp, Forgemasters will manufacture 35 flange and spacer castings for the second phase of construction for the project for Dong E&P A/S.

Ian Nicholls, managing director of Vulcan SFM, Forgemasters specialist subsidiary for bespoke products for offshore oil and gas, said: “As a design and manufacturing specialist our particular expertise is in high integrity steel castings and forgings for this sector.

“The particular operating conditions for this clamp mean that high fatigue resistance is critical to the successful operation.

“Castings offer the ideal engineering solution for this type of situation, but the quality of the component is extremely important. Using the known properties of fracture toughness for the cast material and the extreme loading scenarios for the particular operational conditions an Engineering Critical Assessment has been carried out to determine extremely high quality standards.”

The extreme size and shape of the casting means that an understanding of the dimensional changes that can take place is extremely important to a successful manufacturing effort. RD26 Ltd, Forgemasters’ new R&D subsidiary, carried out computer simulations of expansions and contractions through cooling after casting and through heat treatment, and provided valuable information for the successful production.

The cast material was developed by Forgemasters specifically for this type of operation, combining strength, toughness and weldability. Vulcan and Wilton Engineering, who will fabricate the final assembly, are co-operating in a new range of weldability tests that will extend the weld thickness.

The supply is part of a substantial structural repair project undertaken by DONG E&P A/S and contracted to Subsea 7. 

The clamp which was manufactured and machined at Forgemasters has now been dispatched. The flanges and spacers will be delivered in early 2013.

Vulcan has worked closely with Subsea 7ho have performed engineering critical assessments to determine the appropriate non-destructive testing requirements for this application.