Servicing of Cold Water Extraction Pump

The Problem

A cold water extraction pump from Collinsville Power Station required was stripped and assessed in the Dowdens Pumping, and Water Treatment workshop and the following issues were found and recorded:

• The pump’s wear rings were worn unevenly, indicating shaft run out
• Shaft centre supports and lower support bushes were worn beyond safe tolerance
• Gasket material was missing between the 1st and 2nd stage, revealing the pump housing had spread slightly in the centre
• After the casing and cover survey was completed it was confirmed there was up to 0.028″ hollow in the casing and 0.026″ hollow in the cover – with an average 0.010″
• Impellers worn on ring landings and required machining to suit new wear rings
• The pump shaft had run out on the lower journal
• A foreign object was found in 1st stage impeller (plastic drink bottle)
• The 2nd stage impeller hub was severely damaged.