GRAPHALLOY® Upgrade Saves Boiler Feed Pump

Keeping a multistage boiler feed pump operating was a problem for a gas plant...until they installed GRAPHALLOY bushings and wear rings.

A large industrial gas supplier in the southeastern United States experienced a catastrophic failure of a horizontal 8-stage, axially split, BB3-type multistage pump in Boiler Feed Service. The pump had been fitted with a plastic composite (Teflon®/Carbon Fiber) material for the stationary wear rings and bushings.

They contacted Graphite Metallizing and invited one of our engineers to visit their repair shop to examine the failed pump and recommend a GRAPHALLOY upgrade.

Here is what he saw: the throttle bushing showed the most wear. The sleeve under the throttle bushing was worn with radial grooves that appeared to be from contact with the stationary (plastic composite) wear part. However, in this case, the center stage (typically the first part to fail in a dry run episode or low viscosity transient) was fine while all of the hub side composite inserts were missing and the eye side inserts were unaffected. This tells us that we were looking at a completely different issue.

The engineers agreed that the cross section of the throttle bushing was so thin (only approximately 3/16 inch per side) and the pressure against the face of the bushing was so high that it deformed the plastic composite material causing it to move toward the ID.

The reduced clearance caused the bushing to ride onto the throttle sleeve. The friction and pressure caused the plastic composite material to melt and “blow out” the low pressure side. Once the throttle bushing was lost, the rotor lost its hydraulic balance within the case causing the rotor to shuttle towards the one end. The axial movement separated the mechanical seal faces and overloaded the bearing causing the pump to shut itself down. There was evidence the seal had leaked and the bearings showed signs of having thrust in one direction.

The Graphite Metallizing engineer recommended replacing the hub rings, center and throttle bushings, and eye side rings with nickel-grade GRAPHALLOY. The GRAPHALLOY material was ordered, shipped next day, installed and the pump was quickly put back into service. The pump has been in service now for over four years with no further problems.

The plant engineer explained that GRAPHALLOY was chosen because of successes with other pumps at this site and also for providing fast turnaround on both the quotation and replacement parts.

To learn more about GRAPHALLOY pump bushings and wear parts, please click here.

GRAPHALLOY® Solves Frequent Failures in Petrochemical Plants’ Multi-Stage Pumps

GRAPHALLOY self-lubricating bushings and wear rings are non-galling, withstand high temperatures, and are compatible with a variety of harsh chemicals. One petrochemical manufacturing plant greatly improved MTBF by converting two pumps in Tert-Butyl Alcohol service to GRAPHALLOY. These multistage pumps are used to transfer TBA at a temperature of 110°F.

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Desalination Plant Pumps Upgraded with GRAPHALLOY NSF® Certified Bearings

A major pump manufacturer’s Water Systems Group, which focuses on the commercial and industrial water markets, won a contract to provide vertical turbine pumps for a desalination facility at a publicly-owned water agency.

The pumps would experience dry starts with the possibility of prolonged dry running. In addition, the bearings needed to be NSF certified. These conditions led the pump company to replace their standard bronze bearings with GRAPHALLOY NSF certified bearings.

The unique properties of GRAPHALLOY bearings and wear rings enable pumps to run dry and survive upsets and flashing that cause metal bearings to fail.

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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.