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Interview: Retrofitting conductor centralizers to extend asset life

Lifecycle stage
Late-Life

WHAT SORT OF OPTIONS CURRENTLY EXIST TO REPLACE OR RETROFIT CONDUCTOR CENTRALIZERS?

There’s a range of solutions – depending on the clearance between the guide and the conductor, the loads expected at the guide level and the existence – or not – of any previously installed centralizers.

These options range from our standard retrofit design which is a slim robust, lightweight, 3-piece centralizer capable of being wrapped around the conductor and slipped down into the guide, bespoke designs to fit in the available space between the pre-installed centralizer and the conductor, to adjustable options when the maximum allowable clearance is down to only a few millimetres.

A vertical view of a standard Claxton retrofit centralizer being fitted into a subsea guide.

CAN YOU GIVE US ANY INSIGHT INTO WHAT A TYPICAL PROJECT IS LIKE?

No two challenges are quite the same, but in an ideal scenario, we can take the problem of dealing with centralizers away from the operator. Dealing with retrofitting or replacing centralizers is a fairly specialist activity compared to the full spectrum of challenges an operator has to face when dealing with ageing platforms and conductors.

However, it’s something we do all the time so we can ensure the process is as painless as possible – we’ve literally designed, built and installed thousands of centralizers.

To answer your question though, a typical project starts with a survey of the in-situ centralizers, access and clearance issues, a review of existing records on the platform, riser analysis and any other information of relevance for the design. From there we build outwards and design the most appropriate centralizer and installation methodology.

WHAT ADVICE WOULD YOU GIVE TO OPERATORS? ARE THERE ANY PITFALLS TO AVOID?

My biggest piece of advice to any operator is to be wary of any replacement solution that is permanent or cannot be removed from the conductor guide. You definitely want to maintain flexibility for the future.

Pictured: Just a few of the Centralizers Claxton is supplying for the Total Martin Linge development, offshore Norway.

If you do install something that can’t easily be removed you’re limiting yourself to one future course of action: Cutting the conductor guide away.

You should ensure you can easily recover the conductor, perform a ‘slot recovery’ or have plenty of options if you simply have another asset life extension challenge to solve – either with that particular guide or the array of adjacent guides and conductors.

YOU MENTIONED BEING INVOLVED IN A LOT OF CENTRALIZER PROJECTS – ARE THERE ANY THAT STICK IN YOUR MIND?

We’ve supplied close to 5,000 centralizers so it’s tough to pick just one. However, one standout moment was running our first remotely actuated centralizer – I was really proud of that because the design was the result of a lot of internal engineering and development and as a result, we have reduced the personnel risks associated with the installation process. No other centralizer supplier has a competing design that can be remotely actuated.

remotely actuated centralizer

Claxton’s unique remotely actuated centralizer being run on the West Franklin development.

 

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Asset Life Extension Buyers Guide

Download our structural asset life extension buyers guide for details on slot recovery techniques, centralizers and replacement platform guides.

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