Retrofit conductor guide centralizer solution

How Claxton solved a tricky asset life extension problem for Subsea 7.

The Problem

Subsea 7 approached Claxton when it had to retrofit centralizers in several subsea conductor guides beneath two platforms for an operator in the Norwegian sector of the North Sea. The project was in response to challenges connected with the inaccurate positioning or slippage of the original centralizers.

The Solution

Engineers from Claxton and Subsea 7 jointly examined the specific practical challenges of the project. This led to Claxton modifying an existing centralizer design to produce a slim, lightweight, three-piece centralizer capable of being wrapped around the conductor and slipped down into the guide. The two parties continued to work closely to test the new design thoroughly onshore, develop installation procedures and plan the necessary diving operations.

Claxton was initially asked to supply 10 of the centralizers, all for 26-in. conductors: eight suitable for fitting in 36½-in. guides and two for 34-in. guides. Later, Subsea 7 added one more of the latter design to the order and asked for this to be supplied within two weeks. Claxton delivered the centralizer 11 days after the formal request.
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Retrofit centralizer being lowered into position.

The Result

Subsea 7 reports that the work offshore to install the centralizers went well and was devoid of incident. It was agreed that the success of the project was helped by excellent interaction between Claxton and the client.

Claxton project engineer Ann Vicens Morton is certain this was the case: that the success of this project and others like it was the result of the excellent interaction between supplier and client. “Collaboration is always the key,” she says. “There has to be a willingness to discuss all aspects of the job and to work together to devise a practical, installer-friendly solution to the challenges expected offshore. Solid preparation up-front has the power to save considerable time and, therefore, money during the offshore operations.”

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