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.

Biodiesel Power
The conversion of bio-waste to fuel saves barrels of petroleum. High temperature and an inert atmosphere can convert bio-mass and used cooking oils into biodiesel fuel. Standard bearings fail in this hostile environment. To solve this problem, the engineers at Graphite Metallizing developed a special high temperature grade of GRAPHALLOY and a special mounting to house the bearings.

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. http://www.graphalloy.com

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

Replacing leaded bronze in pumps with Graphalloy(r)

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- http://www.graphalloy.com/html/products.html) 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.

Luis

How will Graphalloy handle our jet fuel pump application?

The principal bearing issue for Jet fuel is its very low specific gravity which makes jet fuel a poor lubricant.

Graphalloy bearings have many applications in very low gravity pumpages (lng, ethane, propane, benzene, CO2 etc.). Graphalloy is excellent for these applications because in these low specific gravity fluids Graphalloy provides a margin of safety allowing moving parts to contact without galling or seizing.

We have a history with aircraft fuel gear pumps (from memory I think these go back to the 60's). Our primarily pump business is in high HP centrifugal boiler feed and process pumps (vertical and horizontal) where low lubricity, flashing or run dry conditions are a possibility. Graphalloy bearings will allow the pump to survive an upset. So we have lots of related experience and are confident that the materials can handle a jet fuel pump but we encourage you to do you own testing in as close to real world environment as possible.

We mostly supply finished bearings/bushings and generally these are custom sized for a specific manufacturer's equipment. Pumps are a large part of our bushing applications. The key Graphalloy material advantage is the ability to run dry or in very light fluids (jet fuel for example) without galling. This permits the pump to run dry for a period and then re-establish pumping without failing. (FYI http://www.graphalloy.com/html/pump.html ).

For a metal pump, the usual design is to install, with a press fit, directly into the housing of the pump. The bushings can be supplied with a metal backing but this is normally not necessary. One advantage to the press fit installation directly into the housing of the pump is that as the temperature of the housing changes the bearing can be designed to maintain both secure mounting and a constant clearance to the shaft over a wide range of operating conditions.

In order to proceed to a design, our engineers will need: pump cross sections and dimensions on housing and shafts, materials of construction, rpm, expected loads and pumpages.

Gear Pump Success for Graphalloy bushings - outlast the plain carbon

When The Competition Said "No",

GRAPHALLOY® Said "Yes"


A chemical plant in Tennessee was experiencing rapid bushing failure in their gear pumps. These bushings were failing after only a few weeks of operation.


When plant representatives contacted this carbon bushing manufacturer about the problem, they were told that there was "no solution". The bushing manufacturer - our competitor - claimed that the viscosity of the polymer being pumped was simply too thick.

Unhappy with this response, the chemical plant engineers contacted Graphite Metallizing for assistance. After studying the problem, our engineers promptly responded by saying "yes, we can help" and that GRAPHALLOY bushings were the solution.

The pump that was failing was a positive displacement, herringbone-type gear pump with internal bushings lubricated by the pumped liquid. The pumpage is a polymer with heavy viscosity (150 -10,000 CPS) similar to a thick latex paint. The temperature can range from 80 degrees to 140 degrees F with a speed of 520 -1,750 RPMs and a load of 155 - 1,980 pounds. This pump has very high bushing loads because of the meshing gear forces. The calculated PV values were up to 500,000 - over four times the maximum recommended level for GRAPHALLOY in submerged services.


The GRAPHALLOY engineers provided a solution designed for applications involving the transfer of viscous liquids. Grade GM 119.3 bushings were recommended because of their load-bearing and corrosion-resistant capabilities. GRAPHALLOY engineers also recommended slight design changes to improve reliability.

The initial order was shipped to the customer and immediately installed.


The pumps fitted with GRAPHALLOY bushings have been operating for over one year without failure...six times the life of the competitor's bushings.

The success of these GRAPHALLOY bearings demonstrates the potential for GRAPHALLOY upgrades in chemical plants. If you have a pump that may benefit from GRAPHALLOY, please contact our sales engineers with details about your application. Or, click here if you would prefer to contact one of our local field representatives.

How does Graphalloy compare to Tungsten Carbide

A reader wrote to ask about the comparison of Tungsten Carbide to Graphalloy.

As you know Tungsten Carbide is an extremely hard, brittle material. As a bearing, it resists wear from abrasives.

Graphalloy is much softer, but can last longer running dry (without lubrication). However, it doesn't stand up to abrasives as well.

Which is better, depends on the application. Go to www.graphalloy.com/html/inquiry.html and give the engineering department a chance to review your application.

Can you give an example of a high temperature use?

GRAPHALLOY has recently been used in a high temperature steam (up to 540C) and inert atmosphere environment to convert wood chips and used cooking oils into biodiesel fuel. Because standard bearings were not an option in this environment, Graphalloy provided a solution. The production of biodiesel fuel is important because it is biodegradable, nontoxic, clean-burning and renewable.

Additionally, it burns much cleaner than petroleum-based diesel, creating about 60% less net carbon dioxide emissions. These factors make it an ideal fuel for buses, trucks and farm equipment. This application design uses several standard bushings as well as custom-sized bushings for their prototype machines.

Graphalloy’s diverse mountings and extensive experience proved valuable in developing a solution for this difficult environment. Alternative fuel manufacturing is a growing field due, in part, to efforts to reduce dependence on petroleum-based fuels. Graphalloy will continue to be a valuable resource for these high-temperature applications.