The Graphite Metallizing Corporation, manufacturer of self-lubricating Graphalloy bushing materials, has announced the success of its iron grade bushings in molten sulphur pumps at a major refinery.

Molten sulphur pumps require a high temperature bushing material and the refinery was using nickel chromium bearings. It opened up the bearing clearances to .020–.025-in to avoid bearing contact with the shaft but this caused high vibration issues approaching 1.0-in/second peak. Graphite Slab

Iron grade bushings reduce vibration

The refinery’s rotating equipment engineer contacted Graphalloy engineers to determine if it could reduce its running clearances by replacing the bushings with Graphalloy, a graphite metal alloy, which is self-lubricating, non-galling and can handle temperatures up 750°F.

Iron grade bushings reduce vibration

Copper Graphite Due to its non-galling qualities, the refinery was able to rebuild the pumps using iron grade Graphalloy bushings with a running clearance of .006–.007-in. The overall high vibration level decreased to a maximum of .21-in/second peak. The refinery has since rebuilt three additional pumps to the same standards using Graphalloy bushings.