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.

High Temperature Bearings for Ovens, Conveyors, Furnaces and Dryers

GRAPHALLOY^® High Temperature Bearings are ideally suited to applications where temperatures are too high to permit the use of oil or other lubricants. These bearings will not soften at extreme temperatures or extrude under load. Many grades are suitable for temperatures to 750°F (400°C) in air. In addition, special grades provide service up to 1000°F (535°C) and higher in non-oxidizing atmospheres.

GRAPHALLOY - a graphite/metal alloy – bearings can be used in bakery and industrial ovens, glass plants, conveyors, dryers, kilns, kiln cars, stokers, soot blowers, oil guns, gypsum board and veneer dryers.

The GRAPHALLOY bearing product line for extreme and high temperatures includes:

• Screw Conveyor Bearings
• 2-Bolt Pillow Block Bearings
• Inserts for Pillow Blocks and Flange Blocks 

Click below for examples of how GRAPHALLOY bearings have solved problems, reduced costs and downtime and increased productivity in high temperature applications:

• Cam Followers for Glass Ceramic Manufacturer
• Replacing Ball Bearings in High Temperature Oven Carts
• High Heat Spells Problems for Traditional Bearings

Visit www.graphalloy.com for more information.

Solving Subpar Pump Performance by Finding the Right Material

A petrochemical manufacturing plant recently faced material-related issues with two fractionator pumps at its performance products plant in Texas. Pump performance was gradually falling off to a point where the pump could not keep up with demand.


By Eric Ford, Vice President, Graphite Metallizing Corporation
Pump Engineer, November 2014 

A petrochemical manufacturing plant in Texas was experiencing frequent pump failures, as often as once every year, on their Worthington model 3UNX-105 multistage pumps. The pumps were being used to transfer Tert-Butyl alcohol at a temperature of 110°F, suction pressure of 10 psi, and a discharge pressure of 500 psi. The fractionator had an operating pump, an installed spare pump, and spare rotors in a warehouse as backups. A spare rotor would be installed into the failed pump, while the damaged rotor was pulled from service and sent for repairs.

The Area Maintenance Engineer started looking for a longer-lasting option to reduce costs. While the pump was originally supplied with stainless steel bushings and impeller wear rings, these were subject to galling on start-up, and during upset conditions. An upgrade to PEEK material resolved the galling issue, but over time the resin binder started to break down allowing critical clearances to increase and pump performance to drop off. The repair shop suggested switching to a higher,more expensive grade of PEEK.

This idea was rejected as there was no guarantee that the new PEEK material would hold up any better as it had not been tested or used in this service before. After more research, the decision was made to replace the bushings and wear rings with nickel-filled GRAPHALLOY^® graphite/metal alloy components, which allow the graphite layers to slide against each other resulting in excellent dry lubrication, is stable chemically, unaffected by ordinary solvents, and can withstand high temperatures without deformation or burning.

The pump internals are 300 series stainless steel. The supplier provided wear rings that were finish machined and installed into the pump’s 300 series stainless steel housings. The new material was installed into the eye and hub-side stationary rings, as well as the throat, throttle and center bushings. The first GRAPHALLOY-fitted spare rotor was installed into the pump. The damaged rotor with the PEEK bushings was sent to the shop and fitted with new graphite-based components.

The pump has been through several start/stop cycles and over a year in continuous service without any indication of increasing wear ring clearance or degradation. It has exceeded the runtimes of the previous bushings

Click here to learn more about GRAPHALLOY.

Is GRAPHALLOY A True “Run-Dry” Material?

GRAPHALLOY® is an alloy of carbon graphite and metal. The graphite provides continuous lubrication without the need for grease oil or other forms of lubrication. GRAPHALLOY deposits a thin film of graphite on the shaft to reduce friction and the metal impregnate help to transfer heat from the rubbing surface to the housing. GRAPHALLOY has much higher temperature limits than many thermoplastics available today. Run-Dry transients will not melt the GRAPHALLOY as it may do to other materials. Normally the pumps can be put back in service immediately after dry running transients while plastics usually require replacement.

For more answers to questions about GRAPHALLOY, click here.