GRAPHALLOY Bushings and Bearings

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Wednesday, March 30, 2011

High Temp GRAPHALLOY® Bushings Handle Hot, Harsh Environments

Self-lubricating GRAPHALLOY® bearings operate in high temperatures up to 750°F (400°C) in air and up to 1000°F (535°C) in non-oxidizing atmospheres. GRAPHALLOY, a graphite/metal alloy is uniform throughout and contains no oil or grease to harden or burn up in high temperatures or under load. Since they do not soften, gum, or seize in hot and harsh applications, as grease-lubricated and plastic bearings may, GRAPHALLOY bearings/bushings reduce maintenance, eliminate need for frequent replacements, and provide trouble-free operation.

Available in over 100 grades with specific properties to suit a wide range of operating conditions, GRAPHALLOY can be used in water, hydrocarbons, weak acids, and alkalies, and works submerged. Commonly used materials are copper, bronze, silver, and nickel.

GRAPHALLOY products include bushings, flange bearings, hanger bearings, pillow blocks, seals, case rings, thrust washers, wheel assemblies, and electrical contacts, and are available in custom designs or as standard components. Typical applications include ovens, furnaces, conveyors, dryers, dampers, pumps, and plating tanks. GRAPHALLOY has received FDA acceptance and can be steam cleaned without damage or performance reduction.

Thursday, March 17, 2011

GRAPHALLOY® Plays a Key Role in Geothermal Energy

Crucial to the Success of Pentane Pumps in Geothermal Power

Pentane is a low lubricity, low boiling point liquid. Whenever there is an upset, pumps in pentane service risk galling. Because of the nature of this pumpage, GRAPHALLOY® wear parts are selected to provide a margin of safety and prevent galling.

Why Pentane in Geothermal?
Geothermal power generation must operate with whatever temperature is found in a particular well. Water and steam work well at high temperatures. At lower temperatures, a "binary system" may sometimes provide better efficiency.

In a binary system, the hot fluid from the geothermal source is used to heat a second, lower boiling point fluid (in this case, pentane) to convert it to gas and drive a turbine. The nature of pentane allows the whole cycle (fluid to gas, drive the power generation turbine, and condense to fluid) to take place efficiently at a lower temperature.

At this location, a binary system is being used to squeeze additional power from the hot condensate leaving a primary water/steam turbine. Using an additional set of heat exchangers this energy is captured to heat low boiling point pentane and to drive an additional turbine. The pentane system harnesses more of the energy brought out of the ground.

Like getting something for nothing.

The Challenge
A major U.S. geothermal power plant experienced difficulties with their pentane feed pumps. The pumps are Goulds model 12RJHC-7 stage vertical can pumps. They have a shaft diameter of 1.5 inches with an 18 inch diameter suction can. Each pump is driven by a 125 HP, 1800 RPM electric motor.

Service Conditions
Flow: 966 GPM
Total Developed Head: 476 Feet
Specific Gravity: 0.58 SG
Temperature: 123° F/51° C
Bearings: originally fitted with bronze bearings

The plant's pentane pumps were experiencing deflections on start-up and shut-down. This caused the rotating sleeves to come into contact with the bronze bearings. Because of pentane's poor lubricity, this can cause severe wear or galling and risks damage or seizing of the pumps.

The Solution
To eliminate this problem, the maintenance staff consulted with the engineers at Graphite Metallizing and converted the bowl and line shaft bearings to a GRAPHALLOY bronze grade. The upgrade was a relatively simple procedure allowing the pumps to return to service quickly. The pumps have been in operation without issues for over 3 years.

GRAPHALLOY bearings have been improving the operation of pumps in difficult applications for almost a century. Graphite Metallizing Corporation, the manufacturer of GRAPHALLOY bearings, has been supplying products to companies involved in the production of renewable energy for 50+ years.

Tuesday, March 8, 2011

Screw Conveyor Bushings for Reliable Service

GRAPHALLOY® Type 1017 Self-lubricating Split Bushings, available from Graphite Metallizing Corp., are ideal for screw conveyor applications.  

GRAPHALLOY bushings with long life and low friction characteristics have a history of solving bushing problems for screw conveyors. These bushings contain no oil to contaminate the conveyed materials and are particularly suitable for screw conveyor installations including agitator or batch mixers. Type 1017 bushings are split to provide for easy installation along the conveyor.  

Type 1017 bushings can withstand dust, chemical attack, caustic liquids and high temperature environments. They provide superior performance in continuous duty operations and in applications where maintenance intervals are infrequent, or where useful life must be prolonged. 

GRAPHALLOY, a graphite/metal alloy formed from molten metal, graphite and carbon, is insoluble in most industrial liquids and is not affected by submersion in most acids, alkalies, hydrocarbons or liquid gases.  GRAPHALLOY does not deform under load and maintains dimensional stability.

GRAPHALLOY products work where oil-based lubricants oxidize and where plastic bushings fail or prove troublesome. GRAPHALLOY bushings are applied in refineries, paper mills, waste-to-energy plants, glass plants, steel mills and power plants.  Grades are available for temperatures to 750˚F (400˚C) in air, and special grades provide reliable service up to 1000˚F (535˚C) and higher in non-oxidizing atmospheres.

GRAPHALLOY bushings and bearings are a proven solution for even the most challenging plant maintenance and new equipment design requirements.