Corus Process Engineering (CPE), part of Corus Northern Engineering Services (CNES), has successfully completed the manufacture and assembly of two, six-metre-diameter steel lifting girdles. These will be used to remove 400-tonne heat exchangers from the reactors at Calder Hall nuclear plant in Cumbria.
Each reactor has four vertically mounted heat exchangers, which are located externally to the reactor building and were clad for insulation and weather protection. The heat exchangers weigh around 400 tonnes and measure 27m in length with a diameter of 5.5m.
CPE customer Nuvia is one of several contractors chosen by Sellafield to decommission the Calder Hall site. Part of the company’s remit was to design lifting girdles and cradles. The lifting girdles were then manufactured and assembled at CNES’ Structural Workshops in Scunthorpe.
The manufacturing process for the carbon steel girdles involved profile cutting and rolling the circular shapes, machining and welding the interfaces between the two girdle halves, assembly, stress relieving, finish machining, painting and delivery.
CNES had to construct spider structures to brace the two halves of the girdle during fabrication. Each half has a trunnion fitted at 90° to the joint face, this required boring a hole in the fabrication, manufacturing and fitting the trunnion to the required tolerance.
The girdles were then stress relieved and finish machined on the joint faces. The fitted bolts used to fasten the two halves together measured almost one metre in length with a diameter of 115mm.
Steve Snowden, CNES Structural Workshops production control engineer, said: ‘Nuvia selected CPE because it trusted us and felt confident that we possessed the necessary technical expertise to carry out the job. We could also handle the front-end engineering that was required, plus provide all the traceability, method statements and other quality assurance-related factors that were key to the project.’