Furmanite has designed and manufactured remote operating machinery to allow pipework to be modified in extremely radioactive conditions.
BNFL required work to be carried out on a pipeline within its vitrification plant at Sellafield, involving the attachment of a branch outlet so that additional pipework can be added. As this work will be undertaken within a highly radioactive area, a fitting that could be remotely clamped around the pipe was produced. The clamping and guidance devices were designed to aid installation and stop the fitting twisting around or slipping down the vertical pipe.
A special mechanical hot tap tee, compatible with Sellafield's existing remote pipe connection systems, was developed to introduce the branch outlet. A drilling machine, purpose-modified for remote operation, was also developed to break into the existing pipework, once the clamping ring was securely in place. The highly radioactive and chemically aggressive pipeline content meant that graphite was used to provide the seal, rather than elastomer sealing connections or metal seals.
Tests on a mock-up showed that the whole system, including the clamping ring and hot tapping equipment, was easy to operate effectively, and was highly cost-effective when compared to robotic alternatives.
Jim Harken, BNFL project manager, commented: “The use of this hot tapping technique and equipment provides a much simpler solution to the problem of adding a new branch pipe than the alternative of welding. The latter technique would have required subsequent radiography of the weld to prove its integrity, and in a remote environment this becomes another difficult task to perform.”