9 Major Reasons of Mechanical Seal Failure in Slurry Pumps

There are several reasons for mechanical seal failures. However, once the seal fails, it causes huge operational and resource loss. Know more about the reasons why mechanical seals often fail with traditional or other available pumps.

Request a Quote

Contact Us

A mechanical seal in a slurry pump is a component used to prevent the leakage of fluid (such as a slurry) from the pump housing along the rotating shaft. Slurry pumps are specifically designed to handle abrasive and corrosive fluids containing solid particles, and they are commonly used in industries such as mining, dredging, and wastewater treatment.

The mechanical seal is typically located at the point where the pump shaft exits the pump housing. It consists of two primary components: a rotating seal face attached to the pump shaft and a stationary seal face mounted in the pump housing. These two faces come into contact with each other and create a sealing barrier.

However, in some cases, the seals break down causing leakage and challenges to the overall operation. These mechanical seal failures can happen due to a number reasons. Let’s shed more light into the roor causes of why slurry pump seals often fail or leaks while in action.

The failure of a mechanical seal in a slurry pump can be attributed to several factors. Let’s have a look at some of the major reasons for mechanical seal failure.

Reasons of a mechanical seal failure

1. Abrasive and Erosive Wear

Slurries often contain abrasive particles that can cause wear on the sealing surfaces of the mechanical seal. The repeated contact between the seal faces and abrasive solids can lead to accelerated wear and loss of sealing effectiveness. This ultimately contributes to the failure of slurry pump seal or mechanical seal failure.

2. Cavitation

Cavitation occurs when the pressure of the slurry drops below its vapor pressure, causing the formation and collapse of vapor bubbles. This phenomenon can erode the seal faces, leading to pitting, surface damage, and reduced sealing performance. Cavitation is among the most common reason a slurry pump seal often fails.

3. Chemical Attack

Some slurries contain chemically aggressive substances that can attack the materials of the mechanical seal resulting in mechanical seal failure. Chemical corrosion can degrade the seal faces, elastomers, or other seal components, resulting a slurry pump seal to fail abruptly leading to leakage.

4. Misalignment and Overloading

Improper alignment of the pump shaft and the mechanical seal can lead to uneven loading and excessive stress on the seal faces. Overloading the mechanical seal beyond its design limits can cause distortion, misalignment, and premature mechanical seal failure.

5. Insufficient Lubrication

Mechanical seals rely on a thin lubrication film to prevent excessive friction and wear between the seal faces. Inadequate lubrication, caused by dry-running or insufficient sealing fluid flow, can lead to increased friction, heat generation, and accelerated seal wear, causing the slurry pump seal to leak.

6. Excessive Heat

Slurries with high temperatures can subject the mechanical seal to thermal stress. Elevated temperatures can degrade the sealing materials, reduce their resilience, and compromise the seal’s ability to maintain an effective sealing barrier. Thus, high or unregulated temperature can cause mechanical seal failure in the slurry pumps.

7. Installation Errors

Improper installation practices, such as incorrect seal assembly, inadequate tightening of fasteners, or improper alignment, can introduce mechanical stress, distort the seal faces, and compromise the seal’s integrity. Once the seal’s integrity is compromised, it results the slurry pump seal to lose its effectiveness resulting in leakage.

8. Inadequate Seal Flush/Quenching

Some slurry pump applications require a continuous flow of clean liquid to flush the seal faces and remove solids or contaminants. Insufficient seal flush or inadequate quenching can lead to the buildup of solids and increased wear on the seal. As the buildup increases overtime, it creates excess pressure on the slurry pump seal causing it to give up its potential strength and expected operational life.

9. Lack of Maintenance and Monitoring

Inadequate maintenance, failure to detect and address early warning signs of seal deterioration, or neglecting routine inspections can contribute to mechanical seal failure. Regular monitoring and proactive maintenance practices are essential to identify and address potential issues before they escalate and result in mechanical seal failure.

Request a Quote

How to avoid mechanical seal failures in slurry pumps?

Lack of knowledge and experience are the main reasons why mechanical seals usually fail. One can easily avoid all types of mechanical seal failures with adequate knowledge and understanding of how the slurry pump seals work or how to fix them to the rotating shaft and the stationary pump housing. Once these points are well taken, one should also understand the below points to avoid mechanical seal failures of any types:

Best Efficiency Point (BEP)

Every pump has a distinct or unique efficiency point on the performance curve called the ‘Best Efficiency Point’. Exceeding this point disturbs the usual flow of the pump resulting in mechanical seal failures. Before equipping a mechanical seal, one has to understand or estimate the BEP for pump correctly to avoid any kind of seal failures in the future.

Net Positive Suction Head

Net Positive Suction Head (NPSH) is a critical parameter used to determine the suitability of a pumping system and ensure proper pump performance. It is a measure of the pressure available at the inlet of a pump, taking into account the fluid properties and the conditions at the suction side of the pump.

NPSH is of two types: NPSH Required and NPSH Available. For a slurry pump to deliver optimal performance, the NPSH Available should always be higher than the NPSH Required. In case the latter exceeds the former, there are high probabilities of mechanical seal failures.

Wrong Adjustment of Control Valve

Insufficiently adjusting the control valve to restrict the pump’s flow can result in flow choking. Choked flow induces recirculation within the pump, leading to heat generation and an increased risk of slurry pump seal failure.

Irregular Venting of Seal

Among various pump configurations, vertical pumps pose a higher vulnerability as their mechanical seal is situated on the upper part. Inadequate venting can cause air entrapment around the seal, hindering the removal of air from the stuffing box. Continuing to operate the pump under such conditions will eventually lead to mechanical seal failure.

Inadequate Vapor Pressure

The vapor pressure margin refers to the variance between the absolute pressure within the seal chamber and the absolute vapor pressure of the fluid being pumped. Mechanical seals run optimally under a sufficient pressure range. In case the vapor pressure increases or decreases, there are high chances of mechanical seal failures.

Request a Quote

EDDY Pump’s Advantage

Switching to EDDY Pump is another great way to avoid mechanical seal failures. The EDDY Pump’s patented slurry pump design creates a negative pressure behind the mechanical seal of the slurry pump, which provides several benefits, including:

Improved Seal Performance

By maintaining a negative pressure or low-pressure zone behind the mechanical seal, the EDDY Pump’s slurry pump helps prevent the entry of slurry or abrasive particles into the seal chamber. This reduces the likelihood of damage to the slurry pump seal or premature wear, improving seal performance and longevity.

Reduced Leakage

The negative pressure created behind the mechanical seal helps to minimize or eliminate leakage of the slurry or fluid being pumped. This is especially beneficial when handling corrosive or hazardous slurries, as it reduces the risk of leaks that could harm personnel or the environment. It also helps maintain process efficiency by preventing the loss of valuable fluids.

Increased Seal Life

The EDDY Pump operating with a negative pressure behind the mechanical seal can extend the seal’s life and other related components. By reducing the exposure to abrasive particles and minimizing the risk of mechanical seal failure, the wear and tear on the seal are significantly reduced. This leads to longer intervals between seal replacements, lower maintenance costs, and increased pump reliability.

Enhanced Operational Efficiency

The presence of a negative pressure zone behind the mechanical seal helps to maintain optimal operating conditions. It prevents the accumulation of solids or slurry particles in the seal chamber, which can otherwise cause blockages or hinder the smooth operation of the pump. By ensuring unobstructed flow and reducing the risk of clogging, the pump can operate at its designed efficiency, delivering the desired flow rates and reducing energy consumption.

Protection of Pump Components

In slurry pumps, abrasive particles in the slurry can cause damage to various pump components, including the impeller, volute, and casing. By creating a negative pressure behind the mechanical seal, the pump can minimize the entry of these particles into the seal chamber and further downstream, thus protecting the internal components and reducing maintenance requirements.

Know more about the: Common causes of mechanical seal failure on a centrifugal pump.

Request a Quote

Related Videos

Common FAQs on mechanical seal failures

Why is my mechanical seal leaking?

Mechanical seal leaks can occur due to various reasons such as improper installation, seal damage, worn-out seals, excessive shaft movement, or inadequate sealing face contact.

What causes excessive heat generation in mechanical seals?

Excessive heat in mechanical seals can result from factors such as high fluid pressure, inadequate lubrication, seal face misalignment, excessive shaft speed, or insufficient cooling.

How can I prevent mechanical seal failure due to dry running?

Dry running, which occurs when the seal faces operate without sufficient lubrication, can be prevented by ensuring proper fluid flow, using compatible sealing materials, and implementing adequate lubrication or cooling systems.

What is cavitation and how does it affect mechanical seals?

Cavitation refers to the formation and collapse of vapor bubbles in a fluid due to low pressure regions. It can cause erosion and damage to mechanical seals by impinging on the seal faces, leading to premature failure.

How can I extend the lifespan of mechanical seals?

To prolong the life of mechanical seals, it is important to follow proper installation procedures, provide adequate lubrication and cooling, avoid dry running conditions, monitor and address any abnormal vibrations or shaft movements, and perform regular maintenance and inspections.

What are some common signs of mechanical seal failure?

Signs of mechanical seal failure include visible leakage, increased temperature around the seal area, unusual noises or vibrations, reduced pump performance, and seal face damage or wear.

How often should mechanical seals be replaced?

The replacement frequency of mechanical seals depends on various factors such as operating conditions, seal design, fluid properties, and maintenance practices. Regular inspection and monitoring can help determine when seals need replacement.

Can I repair a failed mechanical seal?

In some cases, failed mechanical seals can be repaired by replacing damaged components or reconditioning the seal faces. However, it is crucial to assess the extent of damage and consult with experts or manufacturers for appropriate repair options.

Are there specific considerations for sealing corrosive or abrasive fluids?

Yes, sealing corrosive or abrasive fluids requires selecting appropriate seal materials that can withstand the fluid’s properties. Harder face materials and protective coatings may be necessary to resist wear and chemical attack.

How important is proper installation and alignment for mechanical seal longevity?

Proper installation, alignment, and following manufacturer guidelines are crucial for ensuring optimal seal performance and longevity. Incorrect installation or misalignment can lead to increased stress, premature wear, and failure of mechanical seals.

Request a Quote

Still Having Questions? Call Us: 619-345-5446

Tell us about your project. See the custom pump curve page, and we can start the first step of a quote to determine if your project fits our equipment.
Contact Us Here