Component analysis report: Line shaft pump bushings, Warm Springs State Hospital, Warm Springs, Montana

On 29 January 1981, the Failure Analysis Laboratory at Radian Corporation received two spider bushings from the State Hospital at Warm Springs, Montana, for metallurgical analysis. The bushings are from a 19 stage, 200 hp Worthington line shaft vertical turbine pump. The pump was set at 830 feet to test a low temperature geothermal well. One bushing was originally set near the top of the well; the other bushing had been set deep in the well. The bushings were reportedly manufactured from bronze sleeve-bearing material. After approximately 50 hours of intermittent operation, the pump began to experience severe vibration. The vibration appeared random in that it sometimes occurred immediately upon start up and other times occurred after several hours of operation. A Worthington service engineer tested the pump and made several recommendations to alleviate the problem. He concluded that excessive packing box friction, overloading, and shaft unscrewing caused the vibration. He also adjusted the vertical shaft and impeller clearances. The purposes of this analysis is to examine the shaft bushings for evidence of mechanical or corrosion damage that might have been related to the vibration problem