Why do mechanical seals fail?

A mechanical seal is a seal that prevents the leakage of fluid or gases between two rotating or moving parts in the machinery, commonly used in pumps, compressors, and other rotating machinery.

The primary cause of pump downtime often stems from mechanical seal failures. To mitigate this issue, selecting the appropriate seal tailored for the specific function required is important.

Mechanical Seal failure often occurs, but why?

Here are the most common causes for a mechanical seal failing within a process.

Running the pump or machine dry: When a pump is operated without fluid, exposes internal components to high levels of friction and heat, leading to rapid failure. To avoid this, it is crucial to ensure the pump is filled with fluid before operation. If a seal has been dry run, the face of it will be white. Using an AMP sensor can help detect excessive AMPs, preventing further damage by stopping pump operation in time.

Excessive vibration: Vibrations in pumps can be caused by improper alignment, pump imbalance, or operation beyond the best efficiency point (BEP), damaging the machine and shortening the lifespan of the seal.

Hammering couplings: Machines containing components like pistons that have an intense hammering action can induce substantial vibration and movement, posing challenges for both the machine and the seals.

Incorrect Fitting: When a seal is installed, it is designed to have lateral and vertical movement with the shaft. Incorrect installation can cause excess play, damaging forces to the seal. The seal springs can snap and face wear due to restricted movement.

Worn Shaft or Wear: When a seal is replaced certain elastomers such as Viton can increase shaft wear. If the shaft has a smaller OD reduced by friction over the years, then the seal will not fit tightly enabling fluid to leak.

Contamination: Due to inadequate filtration, improper maintenance, or improper handling of the equipment the abrasive particles, dirt, or debris in the sealing environment can accelerate wear on the seal faces causing premature failure.

Excessive heat or temperature fluctuations: Operating the mechanical seal beyond its recommended temperature limits or subjecting it to rapid temperature changes can cause thermal stress, distortion, or thermal cycling that can lead to seal damage or failure.

Fluid incompatibility: Every material has its weaknesses. Exposure to fluids that are incompatible with the seal materials can cause internal parts such as rubber seals, gaskets, impellers, pump casings and diffusers to crack, swell, contract, or deteriorate.

Human error: Simple mistakes by operators can contribute to seal failures for example incorrectly starting the machine, leading to motor tripping and shaft twisting, can result in internal parts movement coming into contact, causing seal failure, and reducing the life of bearings.

To avoid or reduce mechanical seal damage, it is important to follow proper installation procedures, conduct regular maintenance, ensure proper lubrication and fluid filtration, monitor operating conditions, and utilise compatible seal materials for specific applications.

Browse our range of Mechanical Seals on our webstore or contact one of our knowledgeable teams today who are happy to advise on finding you exactly what you need.

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