Oil revenue
Lubricant audits enhance productivity and return on capital

Lubricant audits increase equipment reliability, cut maintenance costs, help companies rationalize the number of lubricants they use, and so increase both productivity and return on capital. This five-step plan shows you how to carry out a lubricant audit on your own plant.

Are you using the right lubricants, in the right places, at the right times? Strategies that were appropriate when the plant was new are not necessarily so as equipment ages or production conditions change. A lubricant audit of your plant can give you the answers you need to increase equipment reliability and save money.
An effective lubricant audit has five steps: pre-audit planning; equipment and site analysis; document review; lubricant report; and stakeholder review. It is essential to seek help from a lubrication expert—often your lubricant supplier—to minimize the amount of time needed for the audit and maximize the benefits.

Pre-audit planning provides auditors with a statistical record of equipment operating conditions and output over given periods of time. Companies will need to compile maintenance records, condition monitoring reports, and equipment inspection reports taken since the last audit or during the last three years. For each equipment item it is important to include information on the manufacturer and model number, lubricants currently used, lubrication frequency and volume, repairs and replacements. Information such as operating temperatures, cleaning cycles and products or system diagrams provide helpful insight later in the process. If the company does not already record this information, now is the time to start a file that can be updated in the future. For example, if a reciprocating compressor operates in an environment where the temperature fluctuates by more than 25°C over a 24-hour period, this is likely to create condensation in the crankcase. Documenting this will be useful in future audits and will help to avoid repetitive maintenance problems.
An equipment and site analysis requires a substantial investment in time, anywhere from four hours to several days. However, the potential cost savings and increased production efficiencies generated from an audit program substantially outweigh the time spent.
The equipment and site analysis monitors the flow of lubricant through each piece of equipment. This offers new insight into maintenance tasks and helps in identifying leaks. If a lubricant appears to be softening, hardening, or losing shear stability, there may be some compatibility issues that can be resolved. Compatibility issues in changing a lubricant, or consolidating lubricant inventories, need to be studied on a case-by-case basis, taking into ac-count the base stocks involved.
Lubricant fittings are also examined for dirt or contamination. Adjustments may need to be made to the filter maintenance schedule to keep the lubricant clean. Any number of factors may compromise the formulation of the lubricant and shorten its life. For large hydraulic systems, or in systems with large lubricant sumps, the breather desiccant should be examined as well, since the presence of water can degrade the lubricant. A properly-functioning breather can dramatically reduce lubricant costs.
Lubricant performance is affected by storage conditions such as temperature, cleanliness and moisture. Check the storage area to make sure that lubricants are protected from the elements. All containers should be labeled and color-coded.
After the equipment and site analysis, documents relating to the equipment and its lubricants need to be reviewed for trends in trace metal analysis, total acid number (TAN) levels, water content, rust, and equipment wear. In plants with high humidity, this review may highlight excessive rust, wear, or corrosion. The lubricant report might recommend switching to a PAO-based lubricant, which improves condensate separation, to increase the service life of air compressors and equipment using compressed air.
Bearing inspections should also be documented. The resulting reports may indicate previous cases of excessive wear, inadequate bearing alignment, or improper lubricant service intervals and volumes.
Companies should consult OEM manuals to check the specified types, amounts, and application intervals of lubricants. These recommendations are often based on conventional mineral-based lubricants; synthetic lubricants may allow service intervals to be increased, but check with the lubricant manufacturer because the performance of synthetics depends on the type of base stock.
The OEM’s recommended lubricant viscosity is usually based on average values for operating loads, speeds and temperatures. These conditions may change, however, to meet new production demands. As a result, a lubricant that differs from the OEM specification may be needed to give optimum performance under new conditions. For this reason, a lubricant audit is recommended at least every three years. The lubricant report is created during the document review. It should include concise tables showing, for each equipment item, the item name, location, current lubricant, and recommended lubricant products. Photographs are also very useful, and are easily added with today’s digital cameras. The tables will highlight areas for potential lubricant rationalization, and help to minimize the risk of improper lubrication, incompatibility, or the need for seasonal lubricant changes. Filter service intervals should also be identified, because effective lubricant filtration has been shown to improve equipment life significantly. Some lubricants contain high-molecular-weight polymer additives that might be filtered out if the filter is too fine, however, so always check with lubricant suppliers and filtration experts.
The lubricant report should also detail any special operating conditions that may affect lubrication requirements. For instance, if a compressor were lubricated with a mineral oil that is thickening under cold conditions, the lubricant report might recommend changing to an ester-based lubricant, which has better low-temperature performance and other characteristics. The last part of the lubricant report is a concise analysis of potential savings. These can be defined in terms of lower inventory through lubricant rationalization, improved equipment reliability, longer maintenance intervals, reduced oil losses through fixing leaks, and extended oil change intervals through the use of synthetics. The final step is a stakeholder review, in which the company’s executives decide whether to carry out the changes outlined in the lubricant report. If the report is clear and concise, and based on sound information gathered with the help of lubrication specialists, the company is likely to see clear benefits.