Case 52: Problems with a blocked-in centrifugal pump

摘要

Over the years I've analyzed several centrifugal pump failures that were the result of a blocked-in discharge. The cause was usually a procedural or initial design error and was corrected after the damage was done. Cracked mechanical seals and vibration occurred in some instances and a total seizing of the pump in others. Most pump books recommend not to run pumps blocked in. When a centrifugal pump is in a no-flow condition, it is still developing horsepower to the trapped liquid. Roughly the no-flow horsepower is 40% to 60% of full flow. This power has to go somewhere and much of it goes into heating the confined liquid in the Casing.