A Comprehensive Guide to Prevent Mechanical Seal Failure

by Mike H. Marketeer

A mechanical seal is a sealing alternative that prevents pump leakage and contamination. It has numerous benefits over its sealing counterpart, gland packing. Although mechanical seals are more cost-effective and provide better sealing, they can fail prematurely due to various reasons. A mechanical seal degrades and must be replaced eventually; however, some other things can cause the seal to fail early. To help you extend the life of your mechanical seals, here’s a list of things that can cause your seal to fail and how to avoid them.

Shaft Misalignment

Shaft misalignment is one of the most common reasons for mechanical seal failure. There are two types of misalignments static and dynamic. Some of the reasons for shaft misalignment are static shaft deflection, seal components being out of tolerance, and improper installation.

Some seal designs are more accomodating of misalignments, whereas others aren’t. It’s important to check for misalignment when installing your seal. Installing a seal in a misaligned shaft can damage your mechanical seal. It can cause the shaft and the seal to rub together, producing heat due to friction. Your mechanical seal manual might have information for an acceptable amount of misalignment. Make sure to check for it before you install your seal.

Unsuitable Operational Conditions

Every seal works the best in a specified range of operational conditions. Anything beyond the range can damage the seal. Therefore, it’s important to ensure that the seal you’re installing is compatible with your process’s operational conditions. Also, make sure your operational conditions stay within the specified range. Any changes can hurt the mechanical seal.

Improper Seal Installation

It’s one of the most common reasons for premature seal failures. No matter how many seals you’ve installed. It’s important to follow the guidelines for seal installations religiously. This is because different seals may have different installation processes. Not following them can lead to improper seal installation, causing damage to the seal once you start with your operations. Always hire an experienced and skilled seal expert to help you with the installation.

No Flush Plans

Flushing plans are essential, especially when you’re dealing with abrasive fluids. They help prevent the abrasives from coming in contact with the seal, keep the things moving in the stuffing box, and help provide lubrication. Not using flush plans can cause the process fluids to enter the seal interface damaging the seal. Make sure you have a proper seal flush plan installed to prevent seal failure.

Chemically Incompatible

Installing a seal that is chemically incompatible with the process’s fluids can lead to seal failure. If the material of the mechanical seal can’t withstand the fluids from the process or is chemically incompatible with them, this can cause your seal to degrade. The seal material can even react with the process fluids affecting the integrity of the seal and the pump.

Dry Running

Letting your pump run dry can be another reason for mechanical seal failure. Running your pump dry can cause a thermal shock due to the excessive friction and cause the seal to shatter. It’s therefore important to have proper lubrication and flush plans in place.

Vibrations and Mechanical Impact

Excessive vibration and mechanical impact can also cause the seal to fail. This can occur due to various reasons such as misalignment, pump imbalance, running the pump away from the best efficiency point (BEP). These vibrations can cause visible damage to the seal, such as cracking and chipping.

Over-Tightening Your Seal

Although it’s a common response to tighten your seal when it leaks, it’s not necessarily the best. Overtightening can distort internal seal components. It’s therefore important to follow the guide when installing the seal. You can use a torque wrench to follow the tightening guidelines in the manual.

Contamination

Although contamination is an issue that arises more commonly when using a gland packing, it can also occur due to a mechanical seal. As seals are placed close to bearings, the contamination due to seal leakage can cause the debris to move towards the bearing. This can cause more debris from the bearing to move toward the seal. This can damage the seal and lead to seal failure. To have a better sealing against contamination, use a double seal instead.

Using the Wrong Seal

Not all seals are fit for all processes and operations. You need to make sure that the seal you’re installing is fit for you. Some of the things to check before installing are:

· Tolerance to misalignment
· Tolerance to vibrations
· Operational temperature
· Operational pressure
· Chemical compatibility with process fluids
· Overall process

Make sure the seal is compatible with all the factors mentioned above before installing it. Installation of a wrong seal doesn’t just hurt the seal itself, but it can also damage the pump.

Mishandling of Seals During Installation

Mishandling your seal during your installation can damage your seal even before it’s fully installed. It’s important to hire a mechanical seal expert to handle your installation. Following are some of the things you should do when handling your seal during installation:

· Don’t unwrap the seal face
· Clean your work surface
· Wash your hands
· Don’t place your seal facedown
· Avoid touching the seal face

Lack of Inspections and Maintenance

Although mechanical seals might not require as much maintenance as gland packing, it’s still crucial to have regular inspections of your seal. Inspections help point out issues early on. This can help you take the right corrective action and prevent your seals from failing. Having regular inspections and maintenance can be really helpful in extending the life of your seals.

About the Author

The author is a mechanical seals expert associated with Robco of America, a mechanical seals company that provides a variety of mechanical seals and services. The author is well-versed in mechanical seal installations and problems and is an expert in dealing with mechanical seal failures.

If you’re looking for a mechanical seals company to find the best-engineered sealing solution for your pump, contact Robco of America.