The Path to Lubrication Reliability

Following the 5 Rights of Lubrication Is Only the Beginning of the Journey

Two wrongs don’t make a right. This proverb states that repaying a wrong deed with another wrong deed doesn’t justify a wrong action. However, can five rights make a wrong? The phrase,“the five rights of lubrication,” has earned its place in the dogma of reliability slogans and buzz words. They are: The right type, the right quality, the right amount, the right place and at the right time. This concise list outlines critical steps for achieving reliable lubrication, but more can be done to achieve lubrication reliability in a machine.

1. THE RIGHT TYPE OF LUBRICANT

“You cannot maintain your way to reliability.” This quote from Reliabilityweb.com^® is spot on. Plants and other facilities have to plan for reliability from the beginning. Installed assets are chosen because of their ability to be reliable. Maintenance is a way to keep these assets running optimally. This includes the lubricants selected for each asset type.

Selecting the ideal lubricant type for the application and the asset is the first step. This choice includes determining primary factors, such as:

• Viscosity;
• Additives in the formulation;
• The equipment’s operating loads, speed and temperature.

Without considering overall system reliability, full plant reliability cannot be achieved. Determining the right type can minimize wear and improve uptime.

2. THE RIGHT QUALITY OF STORAGE AND HANDLING

Quality does not just happen. It requires a deliberate process to control the storage and handling of lubricants from warehouse receiving to delivery at the machine. The steps are simple and easy to measure. That is exactly why it must be measured. Simplicity can lead to complacency. When handling lubricants, only one broken link in the chain of custody can render all prior steps useless.

Lubricants must be tested at receiving to ensure they meet the defined specifications before they are mixed in the storage systems. Simple ASTM tests measure the properties and the cleanliness of the fluid. Then, they most likely need to be filtered and polished to meet the quality specifications for the equipment. The transfer containers must be clean and sealed to prevent any contamination as the lubricant is transferred to the asset.

3. JUST THE RIGHT AMOUNT

The right amount follows the Goldilocks paradigm of finding the level that is just right. Too little lubricant is an obvious problem, but more is not necessarily better. Too much oil or grease can be just as destructive to systems. Extra lubricant volumes may hinder oil slinger rings, as well as splash lube systems. Excess volume also increases bearing operating temperatures and can blow out oil seals.

4. THE RIGHT PLACE

Ensuring lubricant reaches the right place is not as simple as it may sound. Many lubricants are produced in different viscosities. The also have multiple additive packages required for specific machine conditions.

Care must be taken to ensure lubricant containers are color coded and labeled by type. This helps teams prevent mixing lubricants in storage and transfer containers. The same precautions also must be used when labeling the matching points where the lubricant is added to the machines.

5. THE RIGHT TIME

Timing provides the biggest opportunity to improve reliability. Yet, determining the right time to replace the lubricant can be the most subjective. The most diverse opinions and variability from one plant to another involves the timing of lubricant changes.

For example, Company A, B and C may all have the same equipment type in the same operating environments. However, Company A changes the oil every quarter. Company B changes the oil once per year. Company C changes the oil every three years. Why? With this much variability, more reliability engineers and maintenance managers should be asking this question.

If All Is Done Right, What Can Go Wrong?

If the lubricant makes it into the machine clean and fit for use and the operating environment is the same, how does it become contaminated? The answer lies in the oil seals, breathers, filters, or some combination of these components. Seals, breathers and filters have a finite lifetime.

If these components are not maintained properly, the lubricant becomes contaminated and bearing failure begins. Filter life can be measured using differential pressure. These components can be replaced when the pressure differential indicates.

Also, many breathers use a color changing desiccant material to indicate their effective life. They can then be replaced as needed. Deciding when to replace them is not a guessing game.

The function of oil seals is to keep lubricants in and contamination out. Oil leakage is easy to see and measure. Determining the lubricant’s contamination level is more difficult. However, oil testing for contamination is available and is the only way to know whether an oil seal is operating effectively.

Oil seal performance can be measured. Oil analysis reveals how successfully the seal operates and helps determine functional failure rates. Understanding these failure rates is essential to the more ambiguous fi fth right of lubrication, which is to determine the right time to change the oil. This analysis replaces the subjective process, which creates a lot of variability across the industry, with a more objective, precise process for measuring oil life and performance. You cannot improve what you cannot measure. This is the biggest opportunity to improve equipment performance.

The Financial Impact

Companies spend considerable money to ensure proper lubrication. The correct color-coded containers and transfer containers are purchased. Filters and breathers are also kept in inventory. Therefore, these components can be replaced as soon as they indicate the end of their life.

In addition, personnel are trained to know the proper processes and procedures. They learn how to store and handle lubricants from warehouse receiving to delivery at the machine. They learn how much lubricant is added to each machine.

After spending all this money, time and effort, an ineffective oil seal should not be the reason equipment damage or failure occurs.

Oil changes because of contamination may be eliminated or, at the very least, minimized with noncontact, compound labyrinth bearing isolators. They allow for longer periods between oil changes and less oil used. The design of this isolator type, with expeller technology, forces any contaminants out of the seal with centrifugal force. They are moved away from the bearing and lubricant and out of the rotating asset.

When equipment is static or shut down, contaminants enter the bearing housing. A typical bearing housing interacts with the surrounding environment by always attempting to achieve equilibrium (see Figure 1). Under dynamic conditions, the housing vents to the atmosphere because it is at a higher temperature and pressure than the atmospheric side.

Figure 1: Air flow during shutdown

When the machine shuts down, the internal housing cools and because cool air is denser than warm, the bearing housing consumes the air inside and begins to draw air from the atmospheric side as it moves to equilibrium. Moisture and dust accompany this external air. As the contacting O-rings of traditional isolators wear, even more contaminants enter the housing, and therefore the lubricant. These contaminants continue to migrate into the bearing’s housing unless the seal is replaced or a different design is chosen.

Figure 2: The components of compound labyrinth bearing isolators

Noncontact bearing isolators may solve this problem. However, static sealing can present even more of a challenge for a true non-contact seal, such as compound labyrinth bearing isolators. With these seals, the bearing housing still takes in air under static conditions. But, in contrast to traditional isolators, as airborne contaminants and vapor enter, non-contact oil seals break down their energy as they are forced through a series of vertical, throttling gaps (see Figure 2). There, contaminants are captured within the internal condensate trap. They drain out through a small static weep hole at the six o'clock position of the bearing's isolator.