Five tonne Allen Gwynnes pump restored by Axflow 01 November 2011

A 42-year-old Allen Gwynnes cooling water make-up pump for a power station in the East Midlands has been restored by AxFlow engineers.

Weighing in at around 5 tonnes, including the 600kg 30in impeller, the DESC 36in intake, 33in discharge pump had been installed when the power station was constructed in the 1960's, and is one of three extracting water from the adjacent River Trent.

Tom Cooper, AxFlow service base manager, says that scope of service included stripping the pump down and performing a complete dimensional check. Remedial work then included replacing the impeller wear rings and rebalancing the entire rotating assembly.

AxFlow also took the opportunity to convert its upper stuffing box to a split semi-cartridge mechanical seal to allow easy replacement without removing the motor, bearing and coupling. The lower stuffing box was also converted to an un-split cartridge seal.

"Historically, gland leakage led to bottom bearing failure and required constant maintenance to keep the bearing in a usable condition," reports Mark Redgrove, AxFlow technical support manager.

"We reassembled the pump with new bearings, casing wear rings, fasteners and gaskets before filling it with a lot of water to check the integrity of the seals. Once all the tests were complete we painted the pump and organised a fast delivery to site."

And he adds: "Having the facilities to apply Belzona coatings provides us with a considerable advantage when we take on challenging pump refurbishment projects."

Redgrove insists that the coatings not only give excellent protection against corrosion, erosion and cavitation, but enhance the hydraulic performance of the pump, which in turns leads to better operating efficiency.

Brian Tinham

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AxFlow Ltd

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