Anglian Water - 12" pump overhaul
Metalock Engineering has recently overhauled a 25 year old 12-inch Allen Gwynne mixed flow bowl pump thatAnglian Water Supplies used for surface water drainage and which had become noisy, inefficient and tended torun backwards when it was shut down.
The pump had to be dismantled on site as it was too long to remove in one piece from its location due to heightrestrictions in the pumphouse at Cotton Valley STW, Milton Keynes. On stripdown it was found that waterlubrication holes had silted up and blocked causing the bearings to wear away. As a result the impeller hadrubbed on the shroud and worn a deep groove.
Metalock completely refurbished the unit by fitting new bearings and shaft sleeves throughout and building upthe worn impeller with weld followed by machining. A new wear ring was fitted to the back of the impeller. Thepump body was then machined to suit. The impeller shroud was lightly machined to remove the worn area andthe pump reassembled to set the correct clearances.
While this work was being undertaken in Metalock’s Coventry workshops, the non-return valve was completelystripped on site, overhauled and cleaned to prevent water flowing back through the pump. New rubber sealswere fitted and new studs made to replace the old badly corroded ones.
The alternative to refurbishment would have been a replacement pump, the production lead time for whichwould have meant being without a pump for several weeks. Instead, the Metalock overhaul enabled the pumpto be back in operation in 30 days without a need for electrical and location modifications. The success of thisproject indicates that one should not always go for pump replacement in the first instance but contact Metalockwho can provide a quicker and less costly solution.
Metalock repaired this 12” Allen Gwynne mixedflow bowl pump to get it back in service as quicklyas possible. Part of the repair included building upan impeller blade, machining back to originaldimensions and skimming out the impeller shroudto remove a worn area.