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Girdles give biggest lift
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01/07/2008
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Corus Process Engineering (CPE), part of Corus Northern Engineering Services (CNES) has announced the successful completion of the manufacture and assembly of two, six-metre diameter steel lifting girdles that will be used to remove 400-tonne heat exchangers from nuclear reactors at Calder Hall nuclear power plant in Cumbria.
Each reactor has four vertically mounted heat exchangers. These 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. The lift will be the largest ever in the UK nuclear industry. CPE delivered the lifting girdles to its customer Nuvia Limited (formerly NUKEM Limited) - one of several contractors used by Sellafield Limited to decommission the Calder Hall site.
The lifting girdles were 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 (flux cored arc welding) the interfaces between the two girdle halves, assembly, stress relieving, finish machining, painting and delivery.
Machining was carried out at CNES’ Scunthorpe machine shop using a large horizontal boring machine. CNES also 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 necessitated 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. The units were inspected and painted prior to delivery to Nuvia
Steve Snowden, production control engineer at CNES 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. We also understand all the health and safety related regulations that are always our highest priority and we have the necessary fabrication, machining and surface treatment expertise to carry out the work to the required standards.”
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Author
Ken Hurst
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