Most pump failures result from seal failure. That’s the conclusion of William Burke, a fluid sealing specialist. An article he wrote for Pumps & Systems magazine in 1996 has been used as a handout by the Central States Water Environment Association as recently as 2017.
The idea that seal failure precedes most pump failures should be of considerable concern to chemical processors because pump failures are:
- Potentially dangerous to plant employees
- Potentially hazardous to the environment
- Expensive in terms of time and money
Causes of Mechanical Seal Failure
In his CSWEA handout, “Seal Failure Analysis Results,” Burke concludes that three of the leading causes of seal failure in the chemical plants he cites are I.D./O.D. rubbing, O-ring failure and bearing failure. Other problems associated with seal/pump breakdowns include bearing failure, poor installation, the pump running dry, lost environmental controls, worn or opened faces and corrosion.
Bearings, writes Burke, most often fail because of “contamination and water emulsions in a pump’s bearing housing.” He calls for upgrading the seals whenever the bearings are changed.
O-ring failure can be the result of cleaning with a caustic steam solution, Burke says. The answer is upgrading to better O-rings able to handle a harsh environment.
As for I.D./O.D. rubbing, the problem is “rubbing of the rotary seal member against an object, most commonly the bore of the stuffing box.” To fix this issue, Burke notes that installing a seal chamber instead of a stuffing box might be the appropriate response.
Poor installation, dry pumps and lack of environmental controls can probably be chalked up to human, rather than mechanical, error. Worn or opened faces and corrosion demonstrate a lack of appropriate inspection and maintenance—in other words, human error.
CinchSeal: The 3-in-1 Mechanical Seal Solution
Packing seals, lip seals, mechanical face seals, O-rings and other kinds of seals have been around for quite a while and are still in wide use, even in the chemical industry. That said, they’re certainly well tried but not so true. Without proper maintenance, which, with rising cost concerns, is not a given, they fail. And if they do get proper maintenance, it requires considerable expertise and it’s a constant challenge.
As experienced chemical mechanical seal suppliers, CinchSeal high pressure rotary shaft seals have been designed to address the three leading causes of seal failure, and they also go a long way toward solving the maintenance issue. First the reasons for failure:
Contamination in the bearing housing. CinchSeal rotary seals provide these features to reduce the chance of leakage and contamination:
- A larger surface for the shaft/seal interface
- Polished stainless steel-plated and PTFE rotor cups
- O-ring failure.
While CinchSeal custom shaft seals do not feature O-rings, they do feature:
- Silicon elastomer molded slightly smaller than the shaft to achieve an interference fit that prevents material from leaking out
- Purging to establish an air barrier to keep product out of the seal
- Reduction of friction-generated heat by cooling the rotating seal faces, prolonging seal life
- I.D./O.D. rubbing. With CinchSeal rotary seals, damage from rubbing is virtually eliminated. The seals employ an elastomer the spins with the shaft, preventing friction damage.
Reduced Maintenance and Replacement
The evidence is clear that CinchSeal rotary seals are designed to last longer, require less maintenance and extend the replacement cycle. When they do need to be replaced, the process requires considerably less expertise than other kinds of seal.
For example, the CinchSeal 9700 split seal is designed for the harsh environments found in chemical plants. The seal offers these advantages:
- Machined out of stainless steel to withstand caustic wash downs
- Designed split, making installation and conversions simple
- Easily disassembled for batch and weekly cleaning
The Clear Choice
Here’s a summary of the facts in CinchSeal’s favor. Only CinchSeal rotary seals provide:
- A solution to all three major causes of seal and pump failure: contamination, O-ring failure and I.D./O.D. rubbing
- Simpler and less frequent maintenance and replacement for a high level of cost-effectiveness
- An economically advantageous answer to leaks and failures that are potentially hazardous to employees and the environment
Since 1994, CinchSeal has been a major rotary shaft seal manufacturer for for screw conveyors, ribbon blenders and all kinds of bulk handling equipment. CinchSeal products serve as replacements and major upgrades that make the need for machine replacement less likely.
More information on rotary shaft seal manufacturing is available by contacting CinchSeal. Quotes and drawings are guaranteed to be available in 24 hours. Custom engineering usually takes 10 days. Explore our rotary shaft seal catalog to learn more about our products!
