A Comprehensive Guide to Extending the Service Life of Mechanical Seals

by Mike H. Marketeer

The performance factors that affect the service life of a mechanical seal include the actual seal design, pump operation, installation issues, and the seal support system. When it comes to selecting a mechanical seal, you must know everything about its components (faces, O-rings, and metallurgy) to ensure maximum life.

Choosing the appropriate seal type is also critical for every application. Moreover, the right installation procedure must be accurately followed. Here’s your complete guide on extending the service life of mechanical seals.

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Reasons Why Mechanical Seals Fail

What causes the seals to fail, and how can you prevent this from happening? This is a major source of concern among operators and engineers in plants of all sizes and industries. A mechanical seal also refers to a "barometer" for the pump as it helps maintain and operators understand the pump’s health on which it’s installed.

Most often, poor selection of seals and installation errors might as well cause seal failure. If not taken care of, damaged mechanical seals result in pump downtime and account for more costly repairs than any other part of a pump. Here’s what you should look out for.

· Installation Errors

Since installation errors can damage mechanical seals quite easily, they must be installed by a professional. Make sure that the experts follow instructions accurately for a seamless procedure and to reduce chances of failure. Incorrect installation may cause potential damage to other parts of the pump as well as the seal. These errors may include:

- Shaft misalignment

- Wrong assembly length

- Hammering couplings into the shaft

- Using the wrong seal

- Dirt on the seal face

- Axially moving shaft

- Over-tightening of fasteners

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· Poor Lubrication

Poor or absent lubrication around the seal increases friction that raises the temperature inside the pump. The instant temperature change can damage o-strings or rubber and burn elastomeric parts on the seal. Moreover, mechanical seals made of hard materials tend to make a loud noise that causes vibration. As a result, the life expectancy of the seal and the pump reduces.

· Operator Error

Skipping initial start-up procedures and installation errors determine mechanical seal failure. Improperly starting the pump may cause the motor to trip and the shaft to twist, causing orbital movement. When the internal parts come into contact, it may shorten bearing life and cause seal failure. Mechanical seals can be sensitive as the faces are incredibly flat. Even a small amount of dirt or oil can cause misalignment.

Prevent Heat Generation

The commonly used softer carbon face against the harder silicon carbide face prevents heat generation. This is a cool-running combination as an alternate to the seal support system, such as a flush plain. The softer carbon face doesn’t generate as much heat as other combinations. So, it’s a good option for seals without seal support systems.

Proper Installation of Mechanical Seals

Seal installation should be performed according to the steps provided by the manufacturer. Extra care must be taken to avoid damaging the delicate seal faces. Not tightening screws and gland bolts evenly are some of the common installation errors you should keep an eye out for.

Component seal installation can be more vulnerable to errors than cartridge seals because of the extra steps and measurements needed. So, it’s better to choose a cartridge seal over a component design.

Seal Application Limits

This factor refers to the mechanical seal's pressure, speed, and temperature that is prone to misinterpretation. According to most seal manufacturers, the operation of the seal at one of these limits minimizes the life span of two years. There are no fixed rules that explain how much pressure, speed, and temperature a seal can tolerate. You will need expert advice in this area.

Seal Face Deflection

Seal face deflection during a transient depends on the magnitude and rate of the transient and the strength of the seal face. Seal face deflections occur as operating conditions vary and may either improve or affect lubrication of the seal faces. A reliable seal has a low degree of sensitivity to unexpected or expected transients. The seal's sensitivity can be demonstrated through its ability to maintain more or less parallel seal faces during the possible transients.

Are you looking for a reliable mechanical seal company to guide you with your purchase? Robco of America has got you covered. In addition to providing the best sealing solutions, we offer mechanical seals and mechanical seal repair services. For more information, get in touch with us via our website.

About the Author

The author is a mechanical seal engineer at Robco of America specializing in atomizer seal repair and custom design mechanical seals. With years of experience in the field and comprehensive knowledge about mechanical sealing solutions, he also manages and supervises emergency seal repairs.