GRAPHALLOY Bushings and Bearings

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Thursday, May 7, 2009

Go Green with Graphalloy®

GRAPHALLOY®: Finds Its Place In Renewable Energy

GRAPHALLOY bearings are helping to solve the world's energy needs. The advantages of alternate power sources are well-documented. However, because of the extreme nature of the environments required to generate power, it often becomes impossible to use traditional bearings. For years, Graphite Metallizing has been supplying products to companies involved in the production of clean, renewable energy. GRAPHALLOY has proven to be tough enough for these applications. Here are a few examples:

Tidal Power
Tidal power provides an inexhaustible source of renewable energy. A company in New England was seeking low maintenance bearings for a turbine shaft suspended forty feet below the ocean surface. As the tides move in and out, the turbines spin and generate power. GRAPHALLOY bearings proved ideal for this application because they operate successfully in submerged conditions and tolerate abrasive environments like salt water.

Geothermal Power
Geothermal power offers an unlimited source of non-polluting power. GRAPHALLOY provided a solution to the largest geothermal power field in the world by developing a special grade bearing for this severe service. After 25 years, GRAPHALLOY bearings continue to be a critical component of geothermal power generation.

Solar Power
Solar power has proven to be the "ultimate" in renewable energy. GRAPHALLOY bearings are being used in this high temperature application allowing panels to slowly follow the sun while generating high temperature steam.

Graphalloy finds a role in virtually every industry. When you have a tough bearing problem - Graphalloy has probably already found a solution. Call/ email their engineers.

Tuesday, March 24, 2009

Pumps for Ethylene service

GRAPHALLOY® Fitted Pumps
for Survival in Tough Services

Pumps are a major GRAPHALLOY application. The unique properties of GRAPHALLOY enable pumps to run-dry and to survive upsets and flashing that shut-down ordinary pumps.

One Gulf Coast refinery has saved between $150,000 and $300,000 in annual repairs by converting four pumps in ethylene service to GRAPHALLOY. These 19-stage vertical pumps operate at 3560 rpm.

Ethylene is a very light hydrocarbon that creates problems in pump operation. Because of its low viscosity, ethylene provides minimal lubrication to the rotating parts of the pump. As a result, these pumps are prone to failure. The pumps in this Texas refinery were failing two to four times a year at an average cost of $75,000 per pump.

The OEM pump repair shop recommended GRAPHALLOY wear parts based on their success retro-fitting other ethylene pumps. GRAPHALLOY allows the rotating parts to contact without the danger of galling and seizing.

Although it was slightly more expensive than the original metal wear parts, GRAPHALLOY provided a significant cost-savings over composite plastics. The refinery engineer recognized the benefits that GRAPHALLOY could provide and approved the conversion.All four pumps were retro-fitted with GRAPHALLOY. In the three years since their installation, none of the converted pumps have failed. In addition, measurement of discharge pressure showed that the clearances had not opened up in that time.This GRAPHALLOY success in ethylene service demonstrates why so many pump users choose GRAPHALLOY for their toughest services. Ordinary fitted pumps do not allow for run-dry conditions and will not survive upsets and flashing. The unique features of GRAPHALLOY permit dry starts, survive frequent loss of suction, and extend life for continuous service

Wednesday, January 7, 2009

Replacing leaded bronze in pumps with Graphalloy®

An engineer writes:

Asarcon 520 was a lead impregnated bronze used for sleeve bearing in horizontal split pumps. I have not seen it in use since my days at Worthington Pumps in the late 70’s. It was a material highly specified by the marine industry for on board ships, boiler feed pumps and fire pumps. As you can imagine, lead impregnated bearings were capable of running for short periods of times un-lubricated without the rotor disintegrating. The material was readily available in bar stock, however with the issues associated with lead contamination today, I do not believe it is available in the market any longer. To make sure, I would call the local bearing distributor or and bar stock suppliers and see if a similar material is available under some other name.

Years later, while I worked for Exxon as a Rotating equipment engineer we began using graphite/metal Graphalloy (graphalloy- sleeve bearing for pumps and Thorlon for the slower running centrifuges. We retrofitted some old packing pumps with mechanical seals that operated in hot oil services. These pumps, by design, depended on the packing for shaft support. In order to support the shaft and allow the mechanical seal to live, I installed steel encased Graphalloy (with spiral grooves to convey cooling pumpage) between the bearing housing and the old packing box. This eliminated the run out and allowed the seals to run true and consequently not leak. The Graphalloy material can be used in plain stock or encased in a steel sleeve to add strength, depending on need. In either case you must calculate the loads to assure that the bearing is appropriately designed, can support the shaft loads and you do not located your support at a node in the flexural curve.