Repair & Performance Test of a 26/24″ Vertical Split Case Pump

The 6 tonne Mather & Platt 26” / 24” Lonovane Split case pumps were removed from site after failure, and sent to Pump Group with the remit of carrying out a full overhaul and performance test.

The units are used on site at a Coal Fired Power Station drawing water out of the nearby river to be filtered and then used as cooling water for the power generation process. The site normally has 4 pumps installed including one standby. Two of these pumps had both failed within a short period of time meaning that the site was close to a shutdown scenario should anything happen to either of the remaining units.

On receipt at our works the units were cleaned and disassembled and the causes of failure determined. On one unit the shaft had sheared and on the other the upper thrust bearing had failed. On both units this meant the rotating element was able to drop and therefore impact and run against the lower neck ring. The seal mounting sleeves, roller bearings & intermediary make-up sleeves were all damaged beyond a repairable state. New parts were reverse engineered in-house out of Stainless Steel. The mechanical seals were also replaced with new.

Several areas including the cutlass bearing holder and the bottom housing were also rebuilt with Belzona 1111 (Super Metal) which was then machined to size. Belzona Polymer 1111 is a solvent free epoxy resin reinforced with silicon steel alloy which makes it ideal for this application.This was a quicker and more cost effective alternative to completely reverse engineering the damaged areas.

New shafts were machined from EN24T and the impellers were re-ringed to reduce the wear ring clearances to within tolerance. The rotating element was then built and dynamically balanced to G2.5 at 1000rpm.

After assembly, the unit was hydrostatically tested to 1.5 times working pressure. The units are be run in a vertical orientation on site so to enable testing a motor stool plate was manufactured to allow one of the test stock 250 kW motors to drive the pump. A motor stand to support the weight of the motor was also fabricated and used on test.

The unit was placed in our Performance Test Cell, laser aligned to one of our 250 kW motors and performance tested. The units underwent detailed vibration analysis using Pruftechnik VibExpert system and a performance test report was produced and issued to the customer.

For more information on how we can utilise our extensive workshop and testing facilities to assist your company with your operational needs, please contact a member of our Repairs Team on +44 (0)161 864 4678 or via email repairs@pumpgroup.co.uk.