The situation arose when the power station wanted to shut down a single turbine five days in advance of a second. The turbines shared a common two inch connection on the feedwater side and a passing isolation valve on this line prevented an effective isolation.

Furmanite was called in to provide an alternative method of isolation, with three months to find, trial and implement a solution before the outage started.

Two isolation methods were investigated by Furmanite – one using a crimping technique, the other involving hot tapping and line plugging – to provide two possible options for contingency purposes. Both approaches were purpose-developed, the necessary components manufactured, and the methods trialled by Furmanite at its Kendal site on its steam training rig.

The hot tapping and line plugging method involved designing, manufacturing and fitting a box around the pipe and performing two hot taps through the box, to enable plugs to be inserted. This involved cutting into the pipe in two places about 300mm apart, through which the close fitting plugs could be inserted into the line. The section between the plugs was then filled through the box with a Furmanite compound using leak sealing methods, to create an effective isolation plug.

The crimping method, which was ultimately the chosen route, again involved designing, manufacturing and fitting a box around the pipe. In this instance the box was fitted with internal anvils, which could be driven shut using an external hydraulic pump to crimp the pipe in two locations, approximately 300mm apart. The section of pipe between the two crimps was again filled with a Furmanite compound as above, to create an isolation plug.

This method was applied on site in two locations some three metres apart, to create two isolations. The isolated section of pipe between these was then cut out and both ends weld capped to provide a permanent mechanical isolation.

The project was successfully completed on-site in just five days earlier this year.

Commenting on the project, Gwen Parry-Jones, the Sizewell B power station plant manager at the time, said: “This would not have been possible without the dedication of Furmanite’s team of engineers and technicians. The team worked extremely hard to develop and test the techniques, and work was carried out over weekends to meet our tight deadlines. The physical isolation of the pipeline was carried out in a safe, controlled and professional manner. The team even remained on site to provide additional support while the pipeline was being cut and a permanent isolation made.”

Furmanite area sales manager Mark Inder said: “We were delighted to be able to help British Energy overcome this issue with a fully trialled, safe solution. While the crimp option was the selected route we are confident both solutions would have been equally successful. This is an example of the way in which Furmanite is able to understand what is required and engineer a solution to meet the customer’s needs, to minimize downtime and help them keep their assets operating.”

Sarah Manwaring-White, Keep in Touch Ltd,
Tel: +44 (0)1451 844 488
Email: sarah_mw@keepintouch.co.uk