Reliability: Finding upgraded sealing solutions
By universal agreement, the safety and reliability of facilities in the hydrocarbon processing industry—and most other industrial plants—are of highest importance.
By universal agreement, the safety and reliability of facilities in the hydrocarbon processing industry—and most other industrial plants—are of highest importance. That is why modern facilities no longer consider mechanical seals as commodity products wherein only initial cost and timely delivery are given emphasis.
At reliability-focused facilities, mechanical seals are considered engineered products. Best-in-class companies involve one or more of their reliability technicians or engineers in the selection of preferred seal manufacturers. As the quasi-”owners” of a portion of the plant’s machinery, they are intimately involved in vendor selection and performance tracking of mechanical seals. Knowledge of best practices and the advocacy of long-term sealing solutions are listed on the role statements of reliability professionals at best-in-class companies. An actual field example highlights how senior reliability technicians and reliability professionals contribute to mechanical seal success.
When the failure frequencies of sealing products in light hydrocarbon services at their plant did not meet expectations, two professional employees made thorough experience checks. After establishing that Plan 53 was very successful in comparable services elsewhere, they presented their firm recommendations to management. They reached consensus that Flush Plan 53, incorporating a heat exchanger in the flush loop (FIG. 1), should be recommended for services up to 430°F (220°C) at their U.S. refinery.
FIG. 1. API Plan 53C: Pressurized and cooled barrier fluid circulation in the outboard seal of a dual-seal configuration. A tapered pumping ring keeps up circulation while running. Source: AESSEAL Inc.
However, close communication with one of the plant’s technology providers indicated that for several pumps operating with temperatures substantially above 400°F (205°C), the heat load in a Plan 53 circuit could exceed comfortable factors of safety. Attention was then concentrated on API Flush Plan 54 (FIG. 2), where an external pump is used to circulate flush fluid in a closed loop. Plan 54 offers a high rate of heat dissipation and positive circulation of flush fluid. For the record: If properly maintained, this is often considered the most reliable pressurized plan for dual seals. HP
FIG. 2. API Flush Plan 54. Source: AESSEAL Inc.
The Author
Bloch, Heinz P. -
Hydrocarbon Processing Staff, Montgomery, Texas
Heinz P. Bloch resides in Montgomery, Texas. He retired as Exxon Chemical’s Regional Machinery Specialist for the U.S. and has authored or co-written more than 780 publications, among them 23 comprehensive books on practical machinery management, failure analysis, failure avoidance, compressors, steam turbines, pumps, oil mist lubrication and optimized lubrication for industry. Mr. Bloch holds BS and MS degrees (cum laude) in mechanical engineering from the Newark College of Engineering (NCE). He is one of 10 inaugural inductees into NCE’s Hall of Fame, which honors its most distinguished alumni.
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