GRAPHALLOY^® Bearings
Outperform in Dragline Head and Tail Bushings, Electrostatic Precipitators

Customer: Maintenance and fabrication company for pulp & paper, power generations, steel, and cement markets.

Application: Dragline head & tail bushings on electrostatic precipitators. These drag scrapper systems or recovery boiler electrostatic precipitators are located in an extremely harsh environment. Temperatures range from 250°F to 400°F depending on the specific process.

Problem: The fly ash, salt cake, and other process products cover the bearing housings. Reliability engineers struggle to forecast when the bearings will fail. Vibration analysis does not work because of the constant drag chain action on the machine. Visual inspections while the machines are in service are impossible because of the heat and the inability to see the bearings due to process product covering the bearing housings.

When the roller bearing fails, it only takes a few hours to do major damage to the drag scrapper housing, shaft, drag chain, and scrapper blades. Even though the drag scraper is only moving at 25 rpm’s the machines have a tremendous amount of torque foot pounds generated from 100 hp motors. Load cells have been installed on many of the newer machines to automatically shut down when unusual torques are indicated.

Graphalloy Solution: In this particular application, Graphalloy engineers recommended Graphalloy grade 212 bushings with 2-bolt iron pillow block assemblies. Based on customer feedback, Graphalloy bushings run for 4-5 years in this application without issues. The cost savings are easily demonstrated. Customers that have converted to Graphalloy experience a significant reduction in downtime, maintenance and most significantly the head and tail housings are not damaged when Graphalloy is in service.

1/2/2025