Belzona repairs massive water pumps at historic reservoir 04 September 2014

Massive centrifugal pumps at the historic Queen Mary reservoir in Littleton, which serves much of London and surrounding counties, has been restored using Belzona polymers.

The pumps were commissioned in 1924 and were driven by uniflow steam engines, before being upgraded to electric motors. However, years of continuous use had led to cavitation damage – with a hydraulic profile inspection also revealing substrate corrosion to grade D (ISO-8501-1), indicating severe rusting and pitting.

A spokesperson says several refurbishment applications were recommended for three of the pump volutes, totalling a surface area of 282m².

Due to the extent of the corrosion, metal repairs were prescribed, followed by a protective coating. Rebuilding and protection were also necessary for the cast iron substrate, while the impellers – each with a surface area of 44.5m² – only needed through cleaning.

Belzona says all machined faces were protected before bringing in sponge blasting equipment for the upper and lower casings – to remove the previous coating and create a substrate cleanliness exceeding SA 2 ½ with a surface profile of 75µm.

Belzona 1111 (super metal – a solvent-free epoxy resin reinforced with silicon steel alloy) was then selected to rebuild areas of undulation and pitting.

Following curing, and within the specified two-hour window, the first coat of Belzona 1341 (super metal glide) was brush applied, followed by another to achieve a dry film thickness of 400 microns.

Belzona says this coating will now provide long-term erosion and corrosion protection, while also improving pump efficiency.

Indeed, the firm claims that efficiency improvements of up to 7% van be achieved on new equipment, and 20% on refurbished plant, because of its hydrophobic technology.

Brian Tinham

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