CUSTOMER:  BRITISH NUCLEAR FUELS (BNFL), Sellafield plant

PROBLEM: BNFL needed to perform modification work on a pipeline within the Sellafield plant, involving the attachment of a branch outlet so that additional pipe work could be added. Remote operation was an essential as work needed to be undertaken within a radioactive area of the plant.

SOLUTION: Because of its range of specialty services, expertise and knowledge of the appropriate techniques, Furmanite was called in. A purpose-engineered fitting was produced, designed to be remotely clamped round the pipe, using master-slave manipulators. Unique clamping and guidance devices were designed to aid installation and stop the fitting twisting round or slipping down the vertical pipe.

In order to introduce the branch outlet a special mechanical hot tap tee, compatible with Sellafield's existing remote pipe connection systems, was developed.  A bespoke drilling machine, purpose-modified for remote operation, was also developed to break into the existing pipe work, once the clamping ring was securely in place. A further factor affecting design was the highly radioactive and chemically aggressive pipeline content, which meant that neither elastomer sealing connections nor metal seals were suitable.  Instead Furmanite engineers used graphite to provide the essential effective seal.

OUTCOME: This hot tapping technique provided a simple solution to the problem of adding a new branch pipe remotely.