- Buyer's Guide
Has your oil analysis program been running for a few years, or maybe longer, in its current state? Have you been wondering if it could be better? If so, then it may be time for an evaluation and tune-up.
When to Review
We tend to implement programs in our facilities, then leave them to run on their own while we move on to other projects. A comprehensive review of your oil analysis program may be just the ticket to revitalize the program, fix some shortfalls and eliminate some unnecessary testing or sampling.
The review should include the equipment sampled, the lab you are using, sampling locations and frequency, the tests performed, alarms and limits, reporting, the responsibilities of the people involved, training and certification. You will likely find some improvement is needed.
Many plants have had oil analysis programs in place for years. But like most things in life, we continue to learn and want to improve the way we do things. Therefore, it is likely time to revisit your oil analysis program with the latest approaches and technologies.
Room for Improvement
There are improvements to oil sampling in both the selection of the locations from which to sample and the hardware used to obtain a better sample. Laboratory tests have improved as well. Several new test methods have emerged in the past few years related to particle counting, varnish potential detection and antioxidant (and oil) life remaining.
Knowing how and when to apply test methods that have been around for a while has evolved. There are laboratory software improvements for oil analysis data that provide more useful information to maintenance specialists. The calculating and plotting of wear rates, or the rate-of-change of wear, are useful but require good records of the hours that the oil has been in service.
Makeup oil volumes can have a significant impact on wear rates if the volumes vary considerably between oil samples. All of these items could make a significant improvement in the effectiveness of your oil analysis program, making it more cost-effective and more likely to catch major faults before they become costly failures.
In any discussion on oil analysis and especially when evaluating a program, keep in mind that the program should provide (or has the ability to provide) information about the condition of the oil, condition of the equipment and contaminants in the oil.
Also, remember that oil analysis is but one valuable tool in a tool box of many to assist with analysis. Vibration, thermography, ultrasonics and motor current analysis are other tools available to us.
Where to Start
With respect to your oil analysis program, the place to begin is with an evaluation of the current oil analysis program to form a baseline. What is the performance of your current program? What parts of the program are functioning well and contributing to the desired results versus those parts that would benefit from improvement?
An evaluation usually includes a site visit to discuss the current program with several maintenance personnel. During the visit, the oil analysis records are reviewed to check for completeness and to identify the tests being performed. The procedure for taking a routine oil sample is observed to check various aspects of the sampling equipment and procedures used.
An evaluation can consist of 10 categories. These include the following:
alarms and limits
test slate selection
field oil sampling technique
interpretation of data
training and certification
Each of these will be discussed briefly to provide insight into the contents of the category.
Equipment selection involves ensuring that a process is in place to decide exactly what equipment is critical to the function of the plant and should be included in the oil analysis program. It is essential that critical equipment is included; however, there are likely many smaller pieces of oil-lubricated equipment that cannot justify the cost of being included in an oil analysis program.
Selecting a laboratory requires a quick overview assessment of the laboratories used. This could be expanded into performing a complete and detailed laboratory evaluation or audit. During this evaluation, we are determining, in cases where one primary laboratory is used, if that laboratory has an apparent level of competency and ISO certification, and if the oil samples from each piece of equipment are sent to only one laboratory. It is important to determine if any on-site oil analysis testing is performed at the plant level and, if so, whether it is performed properly.
Alarms and Limits
This category assesses the validity or usefulness of the current warning and condemning limits or flags. Who sent the flags and what information are they based on? Are they OEM limits or oil supplier limits, or have they been calculated by the laboratory based on a statistical treatment of historical data? Have they been changed by field staff to reduce the number of alarms received? Alarms and limits are an important factor in the success of the program.
Most maintenance staff members are too busy to look through every oil analysis report and, therefore, rely heavily on the alarms and limits to flag the reports needing attention. If a flag is not assigned to a report by the lab, then that report may not be viewed by the maintenance staff. The improper use of alarms could mean a failing piece of equipment is missed and proceeds into a catastrophic failure.
Test Slate Selection
Test slate selection addresses whether the appropriate lab tests are performed on an oil sample based primarily on the type of equipment, but also on the age of the oil and the sampling frequency. Often, tests are not performed as a cost-saving measure. This needs to be assessed against the risk of not detecting a fault in the machine and, to a lesser degree, against the aging or condition of the oil.
A basic oil analysis package may be less expensive, but it does not provide the information that a more comprehensive test package provides. There can be significant differences from one lab to another in the tests that are included and in the cost of a basic package.
In recent years, there has been an increase in the use of particle count testing, Karl Fischer water determinations and ferrous density measurements, as well as some new technologies such as Fines, Ruler and Qualitative Spectrophotometric Analysis (QSA®) testing. These new approaches and technologies should be assessed for their application to your plant.
This category investigates how the raw data (for example, spectrographic wear metals) is treated and presented. It is important to consider whether just the raw parts per million (ppm) values for each metal are provided, or if wear rates are calculated and plotted based on the hours that the oil has been in service. This is important information.
Most labs provide the end-user with only the raw wear metals data and provide poor-quality plots or graphs of the data. A proper time-in-service is needed to generate a meaningful wear rate. This requires that the field or plant staff provide accurate information on oil changes and how many hours the oil has been in service at the time that the oil sample was taken.
Another factor often overlooked is the amount of makeup oil added during an oil change interval. If widely varying volumes of oil are added as makeup during different sampling periods, then the larger volumes will dilute the wear metals that are generated and give the illusion that the machine is generating less wear. Makeup oil volumes should be noted and considered when calculating accurate wear rates.
Field Oil Sampling Technique
This technique observes how an oil sample is taken from a piece of equipment in the field, and is a critical part of the evaluation. A verbal description of the procedure is not enough. Oil sampling is a critical step in the oil analysis program that occurs early in the process. A poor sample creates inaccurate results. Garbage in equals garbage out.
In an overall evaluation, physically taking an oil sample may be considered the most heavily weighted (most important) category of the program. The oil analysis program cannot recover from a poor sample and the erroneous data that it generates. Clean, new sample bottles and tubing, proper sampling ports and locations are all critical to the success of the program.
The oil sampling evaluation category goes beyond taking a physical sample. The plant should have a comprehensive list of all of the equipment sampled. The program should also include taking samples of the new oils delivered to the plant, both in bulk and in drums. This is necessary to ensure that quality control measures, primarily for contamination reasons, are adhered to by the oil supplier.
A written oil sampling procedure may sound like an unnecessary step, but it will help ensure consistency in the samples taken. The frequency and the consistency of samples can be determined from viewing the oil analysis reports and are important to the success of the program. Samples need to be sent to the lab within two working days to ensure the timeliness of receiving results back from the lab.
Data should be reported to the client and to appropriate plant staff in a timely manner, preferably in an electronic format. This should occur within five working days of when the sample is taken, and a method of reporting highly critical emergency conditions should be established.
Interpretation of the Data
The interpretation of the data is greatly enhanced by having a history of data for the machine and an analysis of the new oil as a reference. Most laboratory reports offer only generic computer-generated interpretation comments for the client. A few organizations offer personal interpretation of the data. The ability of the individual (client) who receives the reports to interpret the data is important, and an assessment of this ability during the interview process is determined.
A chain of responsibility within the organization for acting on the interpretation must be established, clearly identifying who receives the lab results, who is responsible for interpreting them and who is responsible for taking action on those results. Ideally this should be one person.
Training is necessary to keep staff informed of new technologies and techniques. It helps all of us on our continuous quest for improvement. It can provide insight into the reasons why a maintenance procedure is required, and it reminds us of what is important. We tend to develop bad habits and shortcuts that may compromise the value of the work we perform. Therefore, it is a good habit to receive retraining every three to five years on a scheduled basis.
Certification is a means of confirming that the training is effective, and thus provides a sense of accomplishment.
In the evaluation of an oil analysis program, questions in each category are scored and weighted for their relative importance. These figures are then used to calculate an overall score for the oil analysis program of the facility. Areas such as strengths, weaknesses and recommendations are provided, with a priority assigned to recommendations.
This type of oil analysis program evaluation could revitalize an existing oil analysis program which has not kept up with changes or has been only moderately effective over the years. Or, it could improve a program that was not set up properly in the first place. To properly protect your capital investments, evaluating your oil analysis program is a wise step.