Common Failures in Mechanical Seals

Mechanical seals are perhaps one of the most underrated and unappreciated parts of pumps or machines. They ensure that pumps, for instance, do not leak, causing damage to the rest of the machine.

In general, mechanical seals contain the fluid within machines, like pumps and mixers, where a rotating shaft passes through a stationary housing. It prevents visible leaks from leaking. The thing is that machines do leak about ½ teaspoon of liquid each day. But this is normal as the machine captures the moisture and is condensed within it. It also has lightly loaded faces that consume less power. Moreover, the machines suffer from less corrosion because the product or liquid is contained within the pump.

There are different types of seals that machines use and these include stationary seal, rotating seal, balanced seal, unbalanced seal, and mounted seal. The most common seal is the rotating seal and it is used as a component that holds rotating springs together.

The quality of seals is crucial. It is also important to apply the correct seal for the appropriate function. But even if you have chosen the right seal, there will be moments wherein your seals are failing fast. This is especially true if you are working in a plant containing different industries. You have to take note that the mechanical seal serves as the lifeline of the machine. Thus, letting you understand the health of your machine. When the seals are failing, it indicates that your machine might also be failing. There are so many reasons why seals fail and understanding these reasons is crucial to protecting the seal and making it last for a long time. Below are the common reasons why seals get broken.

Letting the Pump or Machine Run Dry

Letting the pump run dry can damage the mechanical seal. Because the seals should not run dry, they are usually designed to allow a thin film of liquid that migrates across the seal faces. If the seals run dry, the friction can cause heat to build up eventually cause damage and leaks. In most cases, the mechanical seal undergoes thermal shock and can disintegrate within 30 seconds after friction and heat have been introduced to it.

Too Much Vibration

Machines do vibrate over time and this is caused by many factors like improper alignment and pump imbalance. It can also be caused by operating the pump beyond its best efficiency point. This means that the machine is operating beyond its normal working point. Machines normally make vibrations as they contain different moving components that produce movements resulting in vibrations. Vibrations can hurt the machine thus resulting in damaged components including reduced seal life.

Hammering Couplings

Machines contain components such as pistons that take on a hammering action. While it is necessary to move the machine, hammering can be very destructive not only for the machine but also for the seals. In some machines, the hammering is so intense that it produces a lot of movement and vibrations. While hammering is inherent among machines that are driven by the piston, it can cause a lot of problems to the seal.

Human Error

Human error can also cause the seals to fail. An example of human error that can lead to damage of seals is skipping initial start-up procedures. If the machine does not start properly, this causes the motor to trip and the shaft to twist. In turn causing movement that results to internal parts coming into contact. It can also lead to failure of the seal and reduce the bearing life. On another note, improperly installing the seal can cause damage to components such as the O-rings. Failure to clean the surrounding of the seals can also lead to failure. Proper maintenance should be given to the seal. The thing is that seals are very sensitive and they can get damaged with even the presence of oil, dirt, and even fingerprints.

Using the Wrong Mechanical Seal

There are different types of mechanical seals out there and it is important that the appropriate seal should be used for a particular machine. Unfortunately, even seasoned engineers lack the necessary information on which type of mechanical seal they should use with their machines. Choosing an inappropriate mechanical seal leads to errors during the installation process. Remember that different machines or pumps handle different kinds of products. You cannot, for instance, choose a seal to handle an abrasive and caustic liquid and expect it to not leak eventually.

If you want to improve the lifespan of your machine, it is important to reduce the mechanical seal failure. You can do this by selecting the right seal and also engaging in good operating practices. While seals look small and disposable, they are very reliable and they can function effectively if they are used and cared for properly.

For more information on a variety of engineered rubber and plastic sealants, machinery devices, laboratory testing, and design engineering, contact Real Seal. Our organization is geared to meet the more fragmenting aspects of industry today. Industrial manufacturers are being tasked with offering consumers more choice, a wider latitude of performance criterion, and greater economic restraints. As American industry continues to evolve to meet the demands of today’s consumers and the challenges of international competition, Real Seal continues to provide solutions and create value.

 

How To Extend Mechanical Seal Life

If you want to drastically improve the efficiency of your pump and reduce maintenance, the first thing to do is change your approach to maintaining your pump. Focus not just on the specialized equipment your plant uses, but on the pipes, valves, and other pieces which are crucial for the plant’s operation.

Did you know that the most common source of wasted energy in pumping systems has to do with seals that weren’t properly sized for their applications? This causes throttling of the pump’s flow, and reduces efficiency. Pumps run in this way also produce higher levels of vibration, which will cause unnecessary damage and reduce the longevity of the seals significantly.

Where does seal failure begin?

While improvements in mechanical seal design have drastically improved their lifespan, using seals outside of their intended environment will cause them to fall short of these estimates. Oftentimes, the problem is that the pump has been used outside of its desired application range. By taking the time to ensure that the entire system is working properly, and fixing problems at their source, you can reach the best efficiency point (BES) and extend the life of your seals.

Root Causes

If a premature mechanical seal failure occurs, there are several common root causes which should be investigated to reach optimal performance for the whole system. In most cases, sealing devices are are being used in an off-design operation. This can cause excess vibrations transmitted throughout the pump, and damages the seals installed in the system.

Avoid these root causes of seal failure

Excessive vibration in the seal chamber cavitation, internal re-circulation, or asymmetrical wear.
Cavitation refers to the vaporization of the fluid and fluid film in the seal chamber.
Temperature increases in the seal chamber under low-flow conditions will cause vaporization of the fluid in the seal chamber.
Insufficient cooling flow from mechanical seal support system.

Critical Seal Components


The mating pair of seal rings is the most sensitive to vibration and insufficient lubrication. Choose these rings carefully based on the conditions of the sealed environment, including the temperature and surface pressures involved. These conditions can change quickly when the seal is exposed to vibration or lacks the sufficient lubrication. Sealing systems try to compensate for changing interface conditions, but off design pump operations may damage the seal if it is forced into a setting it was not intended for. Be wary of more subtle damage which may result from leakage at the seal interface. The cause of this may be unrelated to the material of the seal or its design.

By taking a more involved approach in the subsystems of your pump, you can save money on seal maintenance and improve its overall efficiency. To purchase mechanical seals and other gaskets, visit Real Seal.