Quadna Provides Solutions to Navajo Generating Station


Pumps and Systems Success Story of the Year 2010 Honorable Mention

During a planned nine-week outage at SRP's 2,400 MW Navajo Generating Station (NGS) in Page, Ariz., Quadna tackled the problem of corrosion affecting the 66 x 78 in. split case cooling tower recirculation pump and 66-in. diameter butterfly valves. The pumps and valves had corroded due to exposure to the various harsh chemicals that maintain good water chemistry in the cooling tower.

Quadna recommended a modification to the sleeve-to-sleeve sealing area on the Unit 2 circulation pump that would eliminate crevice corrosion. Quadna also recommended coating the pump's cast iron casing rings to prevent hydrochloric acid from destroying the rings and valves.

For one split case recirculation pump, Quadna replaced the nickel aluminum bronze impeller with a stainless steel 316 impeller and replaced the wear ring housings and related components.

The two butterfly valves, each of which weighed 12,000 lbs, were also rebuilt. They had been in service for more than 30 years.

According to Dana Smith, planner/scheduler for SRP, Vic Lundberg (shown above) "put together the valve rebuild and the coating solution to prevent chemical attack on the valve body and internal components." 

Pumps & Systems, July 2010


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