Graphalloy? self-lubricating wear parts keep pumps from seizing during dry-run, low-flow, start-up, slow roll and shutdown. These are conditions that cause metal-to-metal pumps or plastic wear parts to fail, sometimes catastrophically.

How Difficult Can Pumping Water Be?

A paper mill in the Pacific Northwest was experiencing failures with the operation of three identical boiler feed pumps (two motor driven and one steam-turbine driven). The pumps were 6-stage horizontal split, opposed impeller, channel ring diffuser design. Multistage split-case pumps of this design are susceptible to deflection and vibration during start-up, coast down and upsets.

These pumps were operating in 260?F (125?C) boiler feedwater at 3560 RPM. With the instrumentation available, the operators had a difficult time determining where the pumps were operating on the performance curve.

While attempting to bring the steam turbine driven pump online, the pump was run at zero flow until it seized. Because of a history of failures, the OEM repair centre recommended that the pumps be refit with Graphalloy stationary wear parts. Engineers at Graphite Metallizing Corporation designed a retrofit solution modifying the existing metal wear parts to accept Graphalloy inserts. The case wear rings, diaphragm bushing and intermediate cover bushings were all modified to include Nickel Graphalloy wear parts.

Failure Averted

Soon after this conversion, the pump experienced another incident. A minimum by-pass line was plugged and, as a result, the pump operated at no flow until the users were able to discover the plugged line (located two floors above the pumps). The non-galling, Graphalloy fitted pump not only survived but continued in service. Metal or plastic wear rings would have almost certainly caused a failure. The upgrade to Nickel Graphalloy stationary wear parts allowed these pumps to operate under severely adverse conditions that could cause plastics to melt and metals to seize.

The Graphalloy retrofit provided this paper mill with increased efficiency and reduced downtime.

Consider the advantages of Graphalloy for a typical next pump application:

• Self-lubricating
• Non-galling
• Engineered for specific application, and
• Operates in temperatures from -400 ?F to +1000?F/-240?C to 535?C.

Graphalloy

Used in the manufacture of bushings, bearings and other components for machinery and process equipment, Graphalloy materials are self-lubricating, operate in temperature extremes (from -400?F to +1000?F/-240?C to 535?C) and thrive in harsh environments where other bearings fail.

Graphalloy, a graphite/metal alloy, is a unique self-lubricating bearing material that offers superior performance in hundreds of mechanical and electrical applications. These standard and custom designed products provide lifetime cost savings and significant operating advantages over conventional bushings and bearings.

Graphalloy can be the solution to the toughest bearing, bushing, thrust washer, cam follower, or pillow block bearing design problem. It is available in over 100 grades with specific properties that meet a wide range of engineering solutions and specifications. FDA accepted grades of Graphalloy are available for food contact equipment. NSF? International has certified two grades of Graphalloy material for use in municipal well pumps and water treatment plant applications.

Graphalloy bearings are long-lasting. In some applications, Graphalloy bearings have operated for up to 20 years without maintenance. Standard designs are available but most Graphalloy products are custom designed to the unique requirements of the specific application.

Graphite Metallizing Corporation is ISO 9001:2008 certified and has produced Graphalloy since 1913.

The company is represented in India by: AMT Enviraclean Technologies Pvt Ltd/Advanced Materials & Tribology, Mumbai. Tel: 022-61545454/44, 61545400-03. Fax: 91-22-66430345. Email: info@amtgroup.in