Interpreting an Oil Analysis Report

7/30/2019 Interpreting an Oil Analysis Report

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Interpreting a n Oil Analysis Report - The Top 10 Tips

The final laboratory Report - whether received in an electronic form or ashardcopy - is the axle upon which any oilAnalysis program turns. Without asolid grasp of the underlying principles of reading and understanding the

Analysis report, the inexperienced reader is likely to quickly grow frustratedwith trying to make sense of the seemingly unintelligible test data.However, with just a few basic rules and a modicum of understanding, anyoilAnalysis neophyte can quickly come to grips with reading andunderstanding an oilAnalysis report. The following 10 tips are provided toallow anyone new to the oilAnalysis game to come to terms with his or herreports.

Tip No. 1:

Know the Sampling Point Before Reviewing Its Report

When the moment comes to review your latest set of sample results, it isunlikely that you will have the time to look up each piece of supporting datafor each sampling point as you read. Familiarity with the machines you

monitor, in all senses of the term - operational, mechanical, maintenanceand servicing - is essential for relating mechanical, operational anddocumentary machine information to the oilAnalysis results. Recordingsupporting information, like filter changes and oil top-offs as they happencan also help correlate changes and problems highlighted by the Report tomaintenance activities.

Tip No. 2:

Provide Feedback to the Lab Regarding Your Findings

If you are working with a commercial laboratory, the Report interpretationprocess should be a collaborative process between you and theprofessional analyst. Lab analysts specialize in the chemical and physicaloilAnalysis tests and how they relate to diagnosing mechanical andlubricant-related problems in the sampled system. You, on the other hand,


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have the field experience on the sampled systems operation andapplication. You know the actual result of any actions you took and damageyou discovered based on the data from a given report. Consider the Reportas a locked room full of treasure; but the lock requires two keys to open.You have one key and the analyst has the other. The room will never beopened without timely, routine communication and cooperation. Without theanalysts input, you may never learn in depth how problems on the horizon create changes incertain results, and without your input, the analyst may never learn theoperational details that are sometimes necessary for a set of results tomake sense.

Tip No. 3:

Learn About Magnitudes of Change for Common Test Results

Nothing is more frustrating than seeing a wear metal result change fromtwo to four (a 100 percent increase), only to find that the lab did not flag thedata as significant. This can often leave you wondering if something wasmissed. One key to resolving this situation is to grasp how vanishinglysmall one part per million (ppm) is. To put this into understandable terms,try this: find a standard-size (not jumbo) paper clip composed of iron anddissolve it in one liter (1.06 quarts) of oil. Take a sample of this oil, send itto the lab and have it analyzed. If the lab has perfect calibration on aperfect spectrometer - one able to pick up all the iron in the sample - theresult should come back close to 500 parts per million by weight (thestandard reporting scale for elemental analysis). This illustrates how a largenumerical value may be associated with a small actual quantity of material.When looking at the change in wear metal concentrations from sample tosample, it is important to consider:

the total area of oil-wetted surface in the system that is made of themetal whose level changed, and

the total volume of oil in which the wear metal is suspended.

One of the more challenging aspects of learning how to interpret oilAnalysis data is reaching a reasonable conclusion on whether wear isbeing generated from the entire oil-wetted area of the part(s) composed ofa given metal, or just a small portion of it. For example, in a particulargeared drive with a five-liter oil capacity, iron has increased from 115 to


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281 ppm from one sample to the next. Does this represent wear generatedover the entire two square feet of iron alloy gear surface, for example dueto corrosion, or does it represent two square inches of one side of a flakinggear tooth?

Tip No. 4:

Locate the Worst Reports and Address Them First

You should start by sorting multiple reports by severity/condition status.The severity/condition status statement or code is the labs capsulesummary that characterizes the overall seriousness of the conditionsrevealed by the analysis. It provides the Report reader with a rapid way to

tell if the latest sample from a given sampling point requires immediatereview or action. It is important to sort the samples with the highest priority(critical, alarm, etc.), then the next highest (abnormal, alert, etc.). Once thecritical and abnormal samples have been identified, the reports thatindicate minor result changes but do not require immediate action(marginal, monitor, etc.) should be grouped with the normal sample reports- hopefully the majority of your sampled machines. As a part of this step,glance at the sampling point ID and determine if the systems aremisidentified when compared with the most recentAnalysis samples.

Tip No. 5:

Proof the Reports Clerical Data before Examining the Numerical Data

Verify the Reports RoutingAre you the reports intended recipient? If not, is it because of a simpleclerical error such as a misspelled or incomplete address, or is the samplecompletely misrouted or mismailed? Laboratory clerical mistakes can be

easily corrected by faxing the laboratory a corrected hard copy of thereport. In the case of larger accounts with multiple areas of responsibility, itis essential to provide the lab with accurate names, addresses, phonenumbers and e-mail contact points.Verify the Customer-provided InformationThe content of an oilAnalysis Report can provide information about theeffectiveness of samplers, maintenance personnel and clerical staff at both


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ends of the oilAnalysis process. Missing, incomplete or unacceptableentries may reflect either a failure of plant personnel to provide the data tothe laboratory or a failure of the lab to record it. Either places a limit on thelaboratorys ability to select and apply appropriate guidelines.First, you should review the system supporting information - machine andlubricant information used for interpretation of the test results. Thisinformation is usually found in a block near the top of the form. Note anyreports that have missing or obviously erroneous data for later correctionand forwarding of updates to the lab. Next, look at the difference betweenthe date the sample was taken and the date the lab received it. Anextended time between the sampling date and the day it was received atthe lab may reveal turnaround issues that may not be related to labperformance, such as storing the samples for an extended time beforemailing them or using an inherently slow mail service.

Next, be sure to review the operating data-records of periodic usage orservicing of machine and lubricant since a specified time-based servicepoint (startup, overhaul, oil change, etc.) Unfortunately, in the industrialsetting, the oil time in-service data is often one of the most omitted piecesof supporting data, yet one of the most vitally important. If the time on theoil is not provided, results simply cannot be trended accurately. Almost allwear elements and many contaminants are evaluated on a rate of changebasis. It is also important for the make-up oil - fresh oil added during thesampling interval to maintain a correct oil fill level - to be reported andproperly recorded. Make-up oil additions tend to drive all test values towardnormal as the fresh oil replenishes additives, dilutes contamination andlowers wear metal concentrations.Finally, you should look for missing or obviously incorrect lubricant-in-service data - the oil manufacturer, brand and grade. This customer-provided information is vital to the proper interpretation of the test results,because it underlies all serviceability assessments of viscosity and additivecontent.

Tip No. 6:

Read and Interpret the Report in a Logical Order

Review the Analysts Comments FirstThis step comes before read the test results for a good reason. Bydefinition, the specific purpose for the analysts comments is to interpret


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any significant changes in machine condition as indicated by significantvalues or trends in the data. If you attempt to review the test results beforereading the recommendations, you will often encounter minor sample-to-sample variations which have no diagnostic significance, but which will begexplanation. Having read the analysts comments first, when you do reachthe test results you are already sensitized to the information that thelaboratory professional considers of primary importance. It is, in a sense,like reading the answers before taking the test.Once you overcome your understandable desire to jump directly to thenumbers on your report, review the summary statement, which in mostcases begins the analysts comments. It should give you a conciseoverview of whether the conditions detected fall into the realm ofcontamination, oil degradation or abnormal wear.The condition summary statement will generally be followed by a series of

informative statements which detail each problem, causative factors assupported by data, laboratory or operational experience, and arecommended course of diagnostic or corrective action. First, look overthese statements to see if they make sense from a servicing or engineeringstandpoint for the system being sampled. If you encounter statements thatare incomplete or erroneous for the sampled system, such as drain andflush on a high oil capacity system or shut down immediately on anuclear reactor feed pump, mark the Report for later follow-up with the labanalyst. To drive your decision on what actions need to be scheduled,quickly review the supporting data for any errors that might have led theanalyst to make such statements. If the analysts comments pass thisreasonability test, then move on to a closer examination of their contentfrom a machine condition and diagnostics standpoint.Review the Test DataOn any quality report, test values that have diagnostic significance will beflagged or highlighted in some way (underline, letter code, boldface type,etc.). You should begin your review with these flagged results. If controllimits are printed on the Report along with the as-tested values, you have aconvenient way to judge the severity of the current test results. If limits are

not printed on the report, it may simply mean the laboratory chose not to tryto condense its evaluation for each result into a set of numbers. This choicecertainly does not render the Report useless; it merely increases thereaders dependence on the analysts comments and his or her on-the-spotknowledge and experience in reviewing data.It is best to focus initially on one test at a time. The Report presents a greatdeal of numerical data and text in a small space; it is easy for the eye to be


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overloaded by all the data. To guide your eyes, use the embeddedshadings and lines between vertical and horizontal columns, if yourReportformat has them. When viewing a large number of reports, remember totake breaks - when your eyes are tired it is easy to overlook a small,important detail.When reading the numerical data, take note of the abbreviations used bythe lab for different tests. For example, if the lab Report prints out thechemical symbol for each wear metal instead of the full element name, andyou are not familiar with all of the abbreviations, you may feel a little lost.Try to learn each elements chemical symbol, or ask for a diagnostic chartfrom the lab to explain what each one means. Most labs provide suchcharts free of charge to their customers.Likewise, other test data may be listed under an abbreviated heading likeFTIR-Ox (Fourier transform infrared oxidation data) or RPVOT (rotating

pressure vessel oxidation test). Learn what these abbreviations mean, andmost importantly, how the test data pertains to diagnosing certain problemconditions.Presently, there is no generally accepted inter-laboratory set ofabbreviations for the wide range of physical and chemical properties tests.If coded abbreviations appear instead of full text headings and they are notimmediately understandable, look on the back of the Report for a key to thetest codes. If no key is given, contact your laboratory for a test code key;not knowing what test a given abbreviation stands for is one of the majorsources of reader frustration when scanning a report.

Tip No. 7:

Look for Confirming Diagnostics/Symptoms - The Second Opinion

The medical analogy often used to explain the role of oil and oil Analysis asthe lifeblood of mechanical equipment is appropriate here. If you werediagnosed with a serious condition and your doctor recommended surgery,

it would be perfectly reasonable to seek another doctors advice on whetherthat surgery was necessary. Similarly, when oilAnalysis results come backindicating problems, take the time to see if other condition-monitoringtechnologies being used on that system are also showing alert indications -increases in vibration readings, rising operating temperatures or surfacehot spots near critical parts can all help to support or confirm oilAnalysisdata interpretation. The system operator may also have noticed poor or


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erratic response, excessive noise or an inability of the system to reach full-rated load or speed. Sensory evaluations, performance observations, oilanalysis, vibrationAnalysis and thermography operate on differentdiagnostic principles and each has its own strengths and weaknesses, butmultiple alert indications signal that its time to act.

Tip No 8:

Gauge Your Response - Dont Under- or Over-React

When faced with a confirmed abnormal oilAnalysis report, take it for what itusually represents - an early warning. With a well-planned oilAnalysis testprogram, you often have time to plan your next step. Production and

maintenance scheduling for the affected system may allow you to groupother actions together with those directly related to the oilAnalysis findings.Previous successes in diagnosing problems may also give youmanagement support to take quick action where necessary. In reviewing alldata, but particularly wear and additive element data, remember thatalthough sharp up or down shifts may indicate a serious problem, onesample is not a trend. More often than not, the correct response to a singleelevated reading is to immediately resample and retest to confirm the initialdata. However, also be wary of the most common, usually incorrectresponse to a bad sample Report - an oil change, a little time and anothersample will cure the problem. Ailing equipment rarely cures itself!

Tip No. 9:

Get Into a Report Reading Routine

It has often been said that if you do something every day for six weeks, itwill become a habit. Thats a good approach to reading your oil Analysis

reports. Set up a specific time, and if necessary, a specific place to reviewyour reports. Its best to read reports before scheduling the next daysactivities and well in advanced of scheduled downtime so that anyinvestigation of detected conditions can be factored into the productiontimetable.


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Tip No. 10:

Read Your Reports Today

After Tip No. 9, you might be asking why belabor the point? Every yearthere are cases where, while assisting in root causeAnalysis on the failureof a routinely sampled system, it became obvious that the oil AnalysisReport was ignored completely or simply not read until it was too late. Inaddition, when resamples are needed there is generally a small window fortaking them; if you do not act on the report, the effective resample windowmay close.Much time and effort is spent in creating your lab reports. High-quality oilanalysis, supported by qualified chemists and engineers in the lab, is oneof the most valuable tools in the condition-monitoring toolbox. Labs work

hard to place critical machine condition data at your fingertips - its up toyou to take it the rest of the way.

Editors NoteThis article is an excerpt from a conference paper presented at NoriasLubrication Excellence 2003 conference held in Houston April 1-3, 2003.For a complete full-length version of this article and others on lubricationfundamentals and strategies, oilAnalysis and contamination control best

practices,

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Interpreting an Oil Analysis Report