845 Inserts Solve Problem at Paper Mill

GRAPHALLOY 845 Inserts

GRAPHALLOY^® 845 inserts solved a major problem at a paper mill in South Carolina.  The mill was experiencing production loss due to problems in their forced air dryers.  The dryers were used on a tissue paper line; rapid drying of the delicate paper was essential to the manufacturing process. The 650° F operating temperature in the drying process was causing bearing failures in the roof top damper banks. The result was production down time.

The ball bearings were replaced by GRAPHALLOY inserts.  After only six months operation, the customer was so satisfied that they replaced the ball bearings with GRAPHALLOY inserts on their second production line.

GRAPHALLOY® Extends Bearing Life in Paint Drying Oven

A paint drying oven at a brake shoe manufacturer was experiencing two months life from their roller bearings after being exposed to temperatures of 390ºF (200ºC). In spite of the water cooling system in the rollers, the bearing lubrication was failing and causing roller seizure and extensive maintenance costs.  

Self lubricating GRAPHALLOY^® 845 Series Pillow Blocks were installed, eliminating the need for constant lubrication and the need for the water cooling systems. The 845 Pillow Blocks have run for more than a year with no apparent wear. GRAPHALLOY provided a significant improvement in the life of the bearings.

Fitted Pumps Successfully Run Dry with GRAPHALLOY

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 degrees F (125 degrees 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 center 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 your next pump application:

• Self-lubricating
• Non-galling
• Engineered for your specific application
• Operates in temperatures from -400 degrees F to +1000 degrees F/-240 degrees C to 535 degrees C

GRAPHALLOY® Bearings Cook Up Savings in Heat Treat Ovens

A spring manufacturer was experiencing problems in their heat treat oven. The bearings in an overhead conveyor required weekly lubrication as well as replacement three times a year.  Self lubricating GRAPHALLOY® bushings were installed eliminating the weekly lubrication and the expensive down time.

The spring manufacturer estimates cost savings of approximately $14,000 in lubrication alone. Additional savings were generated by the elimination of the shut down time.

High Temperature Damper Solutions

High temperature dampers can be a maintenance problem. These dampers experience temperatures that require frequent greasing and are often in places that are hard to re-grease. In addition, long periods of inactivity is another source of problems as grease hardens or vibration causes metal on metal galling.

Typical GRAPHALLOY Damper Applications:

• Louver Dampers
• Wind Boxes
• Butterfly Dampers
• Guillotine Dampers
• Diverter Dampers
• Radial Vane Dampers

GRAPHALLOY^® is available in a variety of mounting styles from two and four bolt pillow blocks to two and four bolt flange units. These units are available as solid or split and also come with self aligning features.

GRAPHALLOY provides these "install and forget" features:

• Temperature range from -400° F to +1000° F
• Self Lubricating, requires no oil or grease
• Will not seize or lock up
• Self Aligning capabilities for proper alignment
• Long life, maintenance free operation
• Dimensionally interchangeable with most standard ball bearing units

Bushings that Outperform Metal Wear Parts in CO2 Service

Graphite Metallizing Corporation announces GRAPHALLOY^® wear rings and bushings that provide performance superior to standard metal stationary and rotating wear part in pumps for CO2 service in oil field applications. Self-lubricating GRAPHALLOY, a graphite/metal alloy, eliminates concern about bearing failures or possible flashing of CO₂. 

The ability to operate without additional lubrication is important in CO₂ injection applications because CO₂ has low lubricity. Standard metal wear parts rely on the lubricity of the liquid being pumped for proper operation so they are prone to failures in pumps used to inject CO₂. In addition, due to high suction pressure required to keep CO₂ as a dense phase liquid, flashing is always a possibility.

CO₂ injection in older, low flowing wells is becoming an increasingly popular method for permeating rock formations and forcing more oil to the surface. Many older wells still contain vast amounts of oil locked in the pores of rock layers deep underground. CO₂ injection often releases more oil in older wells than can be released by water injection. 

“Use of self-lubricating, non-galling GRAPHALLOY materials in pumps for CO₂ service provides substantial cost savings by avoiding expensive downtime and field repairs caused by wear part failures,” said Eben Walker, General Manager of Graphite Metallizing Corporation. “GRAPHALLOY is currently the material of choice for many oil field applications in North America and around the world.”

GRAPHALLOY wear rings and bushings operate at longer intervals without the need for replacements or maintenance which helps reduce downtime and maintenance expenses. GRAPHALLOY is an excellent choice for any application where service and maintenance tasks are cumbersome or difficult to perform. GRAPHALLOY is a proven solution for even the most challenging plant maintenance and new equipment design applications.

GRAPHALLOY® Solves Power Plant Damper Failure

Pre-heated secondary air makes the inlet-air section of a utility boiler hot...hotter, in fact, than most steel bearings can handle.

A power plant had difficulty operating the dampers that control the flow of preheated air into the combustors. The hot air quickly dried out the lubricant in the steel damper bearings, causing the dampers to seize.

The problem was solved by replacing the steel bearings with self-lubricating GRAPHALLOY^® bearings. These new bearings have been in operation for years without a single failure.

Failing Dampers Hurt Productivity
Secondary air accounts for 85% of the total combustion airflow to the cyclone burners. This air is heated to 650°F - 750° F (350° C - 400° C) by flue gas through a large heat exchanger. It then flows through a windbox duct to the cyclone burners where it is mixed with powdered coal. Airflow to each burner is determined by an 8’ by 6” by 2’ control damper. The dampers are not moved often and the grease quickly carbonized, locking the bearings.

The utility did not want to bring the unit offline for a bearing problem so it tried to make do. The plant was often forced to alter its firing methods.Frequently, the cyclone burners worked inefficiently due to the inability to control the combustion air. In some cases, it was necessary to fabricate a device to forcefully move a damper manually because operators could not budge them.

The Solution

The power plant solved the problem by replacing the lubricated steel bearings with self-lubricating GRAPHALLOY bearings. Of the 40 bearings used in the plant, 30 consist of three sizes of pillow block bearings while the other 10 are four-bolt flange block bearings.

The upgrade was accomplished during a planned outage. Initially, all of the bearings in one boiler unit were replaced. The GRAPHALLOY bearings ran without any problems and, one year later, the plant replaced the bearings in the other boiler.

The Benefits
The power plant experienced the following benefits by switching to GRAPHALLOY

• The cyclone burners now operate more efficiently because the plant can precisely control the flow.
• Operators are now freed from the time-consuming and distracting task of manually 
• The plant has also had a substantial savings in costs for replacement bearings and labor.

Are you experiencing similar problems with heat and bearing failure? If so, the engineers at GRAPHALLOY will work with you to develop the right solution and help you beat the heat.