Centrifugal Pumps Reducing Seal and Bearing Failures

Centrifugal Pumps Reducing Seal and Bearing Failures 

The mechanical seal of a centrifugal pump in hydrocarbon service is the weak point for any process unit. In 1974, when 1 was the operating superintendent of the Amoco Oil Sulfuric Acid Alkylation Plant in Texas City, 1 discovered two truths about refinery operations  

Half of my time was devoted to the repair and replacement of pump mechanical seals. 

I authorized so much overtime for seal maintenance that our lead machinist purchased a new fishing boat with his extra pay. In 2013, mechanical seals are far more costly and complex, but no more mechanically reliable than in 1974. Their reliability is not a matter of their design, but of the operator s ability to operate, and most especially, to properly start up a pump. A seal may cost 30,000 to 40,000 to repair. Damage to such a seal is cumulative. Meaning improper start-up or operations may not suddenly cause the seal to fail, but will certainly hasten the time when it will fail. 

A seal should maintain its integrity for six years, provided it is operating correctly. Most often seal life is compromised by improper start-up procedures. For example, starting up a pump without venting the seal flush lines to the inner seal on a self-flushed pump may reduce the operational seal life by six months, even though the seal faces have run dry for only a few seconds. 

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Centrifugal Pumps Reducing Seal and Bearing Failures 491... 

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