Deep setting vertical turbine well pumps require pre-lubrication of the standard bronze or rubber bearings between the low water level and the discharge surface. Environmental concerns have now restricted the use of oil and grease. The alternate of water from a local source for start-up requires a complicated auxiliary system. The solution is to use GRAPHALLOY® line shaft bushings which eliminate the need for any pre-lubrication by running dry until pump discharge flow is established. At one installation, the engineer estimated that it would take more than five minutes for the pumpage to reach the surface discharge from the water level. GRAPHALLOY® survived this duration with margin to spare.
Boiler Feed pumps for industrial steam generators are frequently subjected to loss of suction flow during transient switch over. Pumps fitted with metal and plastic wear parts fail in a few minutes of dry running, while those fitted with GRAPHALLOY® have survived and resume pumping when flow returns without wear parts damage. At a chemical plant, three pumps experienced 25 failures in eight years at a cost of $15,000 per failure. Following a GRAPHALLOY® retrofit of all pumps, failures were reduced by 68% and the average repair cost by over 90% during the next five years.
Self-lubricating GRAPHALLOY® has long been the standard bearing in vertical “can” pumps in the refinery tank farm area. The typical light hydrocarbon products have poor lubricity and tendency to “flash”. This, combined with recurring “run dry” operation when the tanks emptied, motivated designers and operators to search for a replacement of the bronze bearing material. GRAPHALLOY® is now the overwhelming choice (recognized by the API 610 12th Edition) for lower wear rates and “run dry” survival.
Pumps with mechanical seals have frequent failures due to excessive shaft vibration. Upgrades using GRAPHALLOY® case rings and close clearance throat bushings provide reduced vibration levels.
