Case Study - 72-inch Power Station Cooling Water Pump

The pump is a Mather & Platt split casing 72" inch cooling water pump, at High Marnam power station. It pumps 93,000 gallons per minute, to a 30 metre head. The purpose of coating the pump is to increase it's efficiency. After being exposed to the river water salts, the internals of the pump start to corrode, causing a scabbing effect to a depth of 5-6millimetres. This can be seen clearly in the image opposite.

Scaled Pump Interior

In order to coat, it is necessary to remove this river salt film of corrosion, by means of needle gunning and grit blasting. In the upper left-hand photo , needle gunning is being performed; this removes the majority of scale.

Once the de-scaling by needle gunning has been performed, the interior is steam cleaned to wash out any salt contamination. Any contamination that is lifted by steam cleaning is then removed by grit blasting.

Descaling Pump Interior by Needle Gunning


Steam cleaning is then applied again to ensure all salt contamination is removed; this condition can be seen to be achieved when flash-rusting is totally orange and no black particulates from salt contamination appear.

The image opposite shows the pump free of all salt contamination.

Salt-Free Flash-Rusting

Finally the surface is grit blasted again to achieve the correct profile of 75 microns (Swedish standard Sa2.5 - near white finish).

Harry Warren Construction strive to always meet this stringent profile standard.

Grit-Blasted Pump Interior

Two coats of Belzona 1341 Super Metal Glide are then applied; the completed pump is pictured opposite.

Impressive efficiency improvements are now enjoyed by the pump operator.

Completed Pump

For more information contact HWC.