With manydisruptions in the supply chain in the recent past, it is becoming commonplace for lubricants to have longer lead times, and in some cases, lubricants may not be available at all. In these times, it becomes increasingly important to optimize the lubricants we are using, our inventory levels and a host of other programmatic issues that lead to the increased usage and depletion of the lubricant. By making a few adjustments to our processes, we can help ensure that we have the appropriate lubricant on hand and plenty of lead time to backfill our supply when needed.
One of the first items that can be tackled is determining if the proper relubrication intervals and volumes are being followed. This tends to be a bigger issue when dealing with greases than with oils. It is common for bearings and other grease-lubricated components to get relubricated every week or two. When you multiply this across a plant with several hundred to several thousand bearings, it can equate to a large volume of lubricant. If you were to determine proper regreasing frequencies, you might find that the component you are adding grease to every week doesn’t actually need to be greased but every couple of months or more. Not only does greasing too frequently result in the overuse of lubricant, but there is a large labor requirement for this as well.
As mentioned, frequency is one side of the coin; volume is the other. It is common practice to “grease it until you see it,” resulting in the damaging of seals and the overuse of the lubricant. By determining the proper regrease volume, we can help minimize this. Using the right volume of grease not only saves lubricants, but the equipment will operate at a lower temperature, and seals will be maintained in better working order.
The importance of lubricant volume also applies to oil-lubricated equipment. Many splash lubricated components don’t have a reliable method to check the lubricant level when in service, which can result in fluid levels that are too high. Not only does this cause more lubricant to be consumed in the initial fill, but it also makes the equipment run at an elevated temperature. The increase in operating temperature reduces the fluid’s life, so more frequent oil changes are necessary. It’s important to also consider the increased energy costs required to churn through the added volume.
Not all lubricants are created equal; some provide additional protection in specific areas, and some perform better in terms of longevity. When selecting lubricants, compare factors such as base oils, additive packages and performance-related tests. Commonly, people refer to tests such as the Rotating Pressure Vessel Oxidation Test (RPVOT) and Turbine Oil Oxidation Stability Test (TOST) to glean insight into how long a lubricant’s life might be. While these tests do provide insight into oxidative stability, you must determine the most likely means of lubricant failure for your equipment and then look at the appropriate test results. For instance, if your fluid is more likely to fail due to hydrolysis (water contamination), then select lubricants that perform better in hydrolytic stability tests. Choosing more stable lubricants may cost extra on the front-end, but you will reduce the number of changes and thus the number of gallons needed on-hand overall.
To dial in frequencies, the use of condition-based maintenance techniques tends to be the gold standard. For greasing, tools such as ultrasound and grease analysis are very common. By performing this analysis, we can make sure bearings, gears and other components are getting greased in the appropriate timeframe (analysis also helps determine appropriate volumes). Oil analysis serves a similar purpose to help change fluids only when the need arises. Also, the condition of the oil can be monitored so that action can be taken when contaminant levels rise, which, in turn, extends the life of the oil. In some cases, based upon the condition of the oil, you could avoid a complete changeout and potentially opt for a bleed-and-feed or partial changing of the oil. This can be done to extend the current charge of oil until such time that a full change can be performed. Lubricant analysis is a powerful tool, especially when it comes to helping you identify ways to extend intervals and change lubricants only when prescribed.
Another place in the program where good lubricants can go bad is storage. Oils that sit in packaged options or bulk tanks can become contaminated, shortening their lifespan. Additives can separate in storage as well. To help minimize either of these from occurring, proper storage activities should be followed. This includes keeping lubricants sealed and in climate-controlled areas as much as possible. For bulk storage tanks, this may also include the use of kidney-loop filters. Periodically circulating the stored oil helps remove any contaminants that ingress, keeps additives in solution, and generally helps maintain the lubricant in a better condition prior to use. Lubricants that are stored outside and allowed to breathe in dirty, wet air often aren’t fit for service and need to be disposed of before ever being used.
In the case that inventory levels can’t be maintained, plan ahead for any oil changes. Work with your supplier to find an oil or grease that is compatible and whose operating characteristics are as similar as possible. Doing compatibility tests ahead of time allows you to quickly make the transition and lets you know if you need to flush the systems or simply do rolling changeouts. With the way the market exists right now, having a couple of candidate options available can save headaches that may arise later.