What Happens When Mechanical Seals Fail on Centrifugal Pumps

Mechanical seals are critical components in centrifugal pumps. Seal failure can lead to leaks, damage, and downtime.

This post explores what happens when mechanical seals fail.

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When a mechanical seal fails, it can no longer effectively contain the fluid being pumped. This leads to leakage of the fluid from the pump.

Loss of Pump Efficiency

Some of the energy intended to move the fluid is lost as the fluid escapes through the damaged seal. This decreases the pump’s overall performance and can lead to increased energy consumption.

Sleeve / Shaft Wear

A damaged mechanical seal can allow abrasive particles or contaminants to enter the space between the seal and the pump shaft or sleeve. These particles can cause excessive wear on the shaft or sleeve surface. Over time, this wear can lead to further seal damage and increased leakage.

Bearing Damage

Leakage from a failed mechanical seal can contaminate the pump’s bearings. The presence of fluid and contaminants in the bearing area can cause corrosion, increased friction, and eventual bearing failure or seizure. Bearing damage can lead to increased vibration, noise, and further damage to the pump.

Gouging, Denting, Scratching of Shaft

When a mechanical seal fails, the seal faces may come into direct contact with the pump shaft. This contact can cause gouging, denting, or scratching of the shaft surface. The damage to the shaft can create additional leak paths and worsen the seal failure.

Corrosion of Seal Shaft

Leakage from a failed mechanical seal can expose the seal shaft to corrosive fluids. Over time, the shaft material may corrode, leading to pitting, weakness, and further seal damage. Corrosion can also affect the seal faces and other components, accelerating the failure process.

Flashing or Etching

In some cases, the leaking fluid may vaporize as it passes through the damaged seal. This vaporization, known as flashing, can cause etching or erosion of the seal faces and shaft.


Fretting occurs when there is small, relative motion between the mechanical seal components and the shaft or sleeve. A damaged seal may allow increased vibration or movement, leading to fretting.

Abnormal Noise

These noises may include squealing, screeching, or grinding sounds. The sounds are caused by the seal faces rubbing against each other or other components in the pump.


The vibration is caused by the imbalance created when the seal faces are no longer properly aligned. The vibration can cause damage to other components in the pump, such as bearings and impellers. Excessive vibration can also lead to premature failure of the pump.

Increased Temperature Around the Seal Area

The increased temperature is caused by friction between the seal faces or other components in the pump. The heat generated can cause damage to the seal and surrounding components. Excessive heat can also cause the seal faces to warp or crack, leading to further leakage.



Can mechanical seals be repaired, or do they always require replacement

In most cases, mechanical seals cannot be repaired and must be replaced when they fail. Attempting to repair a damaged seal can result in suboptimal performance and may lead to premature failure.

How often should mechanical seals be replaced in centrifugal pumps

The frequency of mechanical seal replacement depends on various factors, such as the type of fluid being pumped, operating conditions, and seal material. Consult the pump manufacturer’s recommendations and establish a preventive maintenance schedule accordingly.

What should you do if you suspect a mechanical seal failure in your centrifugal pump

If you suspect a mechanical seal failure, it is essential to shut down the pump immediately and investigate the issue. Continuing to operate the pump can exacerbate the problem and lead to more extensive damage.

Can a centrifugal pump continue to operate with a failed mechanical seal

While a centrifugal pump may continue to operate with a failed mechanical seal, it is not recommended. Continuing to run the pump can lead to increased damage, reduced efficiency, and potential safety hazards.


Mechanical seal failure in centrifugal pumps can cause significant issues. Proper maintenance, monitoring, and timely replacement are essential.

Consult with seal experts to optimize seal performance and minimize the risk of failure. Contact us today to learn more about our seal maintenance and replacement services.

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