ALS Tribology eSource
September 2010

How Oil Analysis Can Fit Into Industrial Equipment Maintenance Practices for Equipment Reliability
by David Doyle, CLS, OMA I & II
Vice President & Operations Manager, North America

How does oil analysis fit into your industrial equipment reliability practices and maintenance program?

Some industrial applications use oil analysis in conjunction with scheduled preventative maintenance (PM). This is primarily done because it works into a convenient sampling routine for the in-service lubricant and complements routine maintenance practices if timed properly. Preventative maintenance normally addresses planned maintenance and OEM recommendations and requirements. This sampling routine may not always provide the most optimal benefits of oil analysis for some applications. Under these circumstances, using in-service lubricant analysis as a maintenance tool might only provide rudimentary benefits. Scheduled preventative maintenance alone may result in too much or too little maintenance activity.

A more proactive approach is using in-service lubricant analysis to perform predictive maintenance (PdM) of industrial equipment. The advantage that predictive maintenance has over scheduled maintenance is that maintenance is determined by what is actually occurring with the health of the equipment at any given time. For example, if it is determined through oil analysis that a bearing or gear is starting to fail, repairs can be scheduled before unexpected downtime occurs and work activity is interrupted. With predictive maintenance through in-service lubricant oil analysis, maintenance can be scheduled well enough in advance so that downtime does not greatly affect work schedules. Predictive maintenance using oil analysis allows corrective action to be performed well before equipment performance deteriorates and indications develop that equipment is going to fail. Under these circumstances, not only would a failed bearing require unexpected replacement but many times additional components will suffer damage. In order to optimize equipment maintenance based on equipment condition detected through in-service lubricant analysis, sampling schedules should occur at regular intervals, including between oil drains.

Many facilities currently use a process called Reliability Centered Maintenance (RCM). Reliability Centered Maintenance is a process that is intended to establish acceptable minimum levels of maintenance in order to optimize equipment reliability. The use of in-service lubricant oil analysis through predictive maintenance techniques in addition to traditional preventive measures can be a key component in Reliability Centered Maintenance. Predictive maintenance through oil analysis can be used to improve scheduled maintenance by either bringing to light additional issues that scheduled maintenance needs to address or by optimizing the timing of scheduled maintenance.

When taking oil analysis to the next level for optimizing equipment reliability, root cause analysis focuses on the source equipment failure and maintenance issues. While with predictive maintenance there is a tendency to treat the symptom rather than the underlying fundamental problem, root cause analysis targets and measures the real problem cause. Generally, root cause detection through oil analysis focuses on contaminants or operating conditions that lead to real problems. Contaminants such as dirt, water, coolant, or incorrect fluid can be detected. Adverse operating conditions can be detected by looking for signs of oil degradation due to excess heat or inadequate fluid film due to improper viscosity. The cost of eliminating the root cause that leads to symptoms of degraded equipment reliability is much less expensive than fixing the symptoms after they occur. Eliminate the cause, prevent the problem from recurring.

By using oil analysis to complement maintenance practices and using the resulting data as proactively as possible, the return on investment (ROI) can be greatly increased in industrial applications. Using oil analysis to optimize predictive maintenance or reliability-based maintenance can easily result in a ten-fold return on investment when compared with only using oil analysis during scheduled preventative maintenance practices. If root cause analysis to keep contaminants below a threshold level that affects equipment reliability or detrimental operating conditions are caught before there is a negative impact, the return on investment for the cost of oil analysis can be even greater.

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