Use root cause analysis to examine failure of a cooling water pump

摘要

Most plants have a bad-actor elimination program, but sometimes operators fall into the trap of normalization of deviation. Normalization of deviation is a long-term phenomenon in which a lower standard of performance becomes the accepted norm; when that occurs, the root causes of failures remain undetected. This case study focuses on a 250-hp steam-turbine-driven cooling water pump in one of Suncor Energy Inc.'s plants in Canada. The plant had four identical vertical cooling water pumps, of which three were operated and one was kept as a spare. One of the pumps was steam-turbine-driven, and the other three pumps were electric-motor-driven. From installation in 1982, the steam-turbine-driven pump remained a bad actor for 24 years, with a mean time between failures (MTBF) of approximately 1 month, whereas the electric-motor-driven cooling water pumps had an MTBF of 60 months.