Getting Started with Lubrication ManagementAre you waiting until you’ve implemented basic lubrication management strategies before taking those first oil samples because they might be bad? Don’t hesitate to start your program. You will likely see many problematic oil samples, but that is no reason to delay sampling. Oil-related problems are opportunities for your lubrication management program. The worse the problem is, the better the opportunity for a cost-effective solution resulting in big savings. Start sampling before you make improvements to establish lubricant condition baselines. The initial oil analysis results provide direction of the solutions to implement.
What to Look ForWhen you receive your first oil sample results, you will most likely see a number of abnormal sample reports. You may even see some critical sample reports. The main issues to watch for are water contamination, high levels of oil particulate, improper oil top-up and poor oil condition.
Figure 1. Listed above are the most common oil-related issues uncovered by oil analysis and their associated general warning limits.It’s possible that you will have sample reports showing abnormal or severe wear in some machines. However, the purpose of establishing a lubrication management program is to maintain proper lubrication to avoid unnecessary wear. So let’s assume your reliability team is assessing these reports and has the situation in hand. Focus on the oil-related problems. Let’s concentrate on water and dirt for starters. Water will show up on your sample report as “water” or “H2O.” Are these results abnormal or severe? At this point, you have not set any alarm levels for water contamination. It is fine to use the laboratory defaults for your industry and type of machine. With most rotating equipment, the contamination limit for water will be 0.1 percent water. Limits range as low as 0.03 percent for turbines and as high as 0.2 percent for gearboxes. Some compressors using certain synthetic oils go as high as several percent water. Dirt will show up on the sample report under silicon (Si) along with elemental data for wear and additives. If you are sampling machines with oil filtration, the laboratory should perform particle count testing. Ensure that you are purchasing the correct test kits for this type of machinery. Pay attention to the ISO cleanliness code as well as the particular particle counts by micron size. Abnormal or severe silicon levels and/or particle count results indicate a problem with contamination. Again, the laboratory will be using typical industry limits for silicon and oil cleanliness. This is fine when you are starting your oil analysis program. Typical silicon alarm levels for most equipment are around 25 parts per million (ppm). ISO cleanliness codes for filtered systems are typically around 19/17/14. Improper oil top-ups are a bit more difficult to detect. Look for comments about changes in the elemental additive levels like phosphorus, zinc, magnesium, boron, barium, sulfur, etc. Monitor any changes in oil viscosity that are +/- 10 percent from the oil specification. Elemental additive levels can fluctuate as much as +/- 25 percent. A laboratory looks for other elements that shouldn’t be present or the lack of an element that should be present. Some labs have very sophisticated algorithms that not only compare the used oil to the new baseline but can determine the fluid type and compare this to the generic fluid type for the oil you have specified. They can alert you when a different type of fluid is being used. You may want to inquire whether your laboratory has the ability to perform this level of comparison. The most blatant types of improper oil top-up or incorrect oil use is when the viscosity varies drastically from the specification. For instance, this would include when you state that you are using an ISO 320 gear oil and the oil viscosity is actually 100 centistokes (cSt). This indicates a possible top-up with hydraulic, compressor or circulating oil. For most lubricated plant machinery, oil condition is monitored using the oil’s acid number (AN). When the oil oxidizes, it forms acidic degradation products. Increasing the AN indicates oil degradation. Once the AN is over the limit for the oil, it’s time to schedule an oil change. Large systems like turbines require more advanced testing. This includes rotating pressure vessel oxidation testing (RPVOT), water separability, rust characteristics, foaming characteristics and air release to determine if the oil is suitable for continued use.