Developing a robust oil sampling program can be a rewarding effort when these essential foundations are put in place:

• Meticulously selecting equipment to monitor with oil analysis, using a suitable criticality assessment.
• Setting the initial oil sampling frequency for each selected piece of equipment. For this objective, ISO 14830 recommended FMSA analysis, which shall be carried out in accordance with ISO 13379-1, to determine initial sampling and inspection periods [1].
• Careful selection of an oil analysis lab, specifying the appropriate analysis slates, and ensuring the delivery of independent and accurate results.
• Providing thorough training for personnel involved in the oil sampling process while fostering awareness of the importance of collecting only representative equipment samples. Establish an internal procedure to help ensure oil samples are truly representative.

These steps are crucial for ensuring the oil sampling program’s success and initiating the next phase of the oil analysis program, which focuses on using the results to monitor equipment and lubricant condition.

However, it’s essential to understand that simply carrying out these steps doesn’t guarantee successful implementation.

Oil sampling becomes part of routine operations only when it consistently runs smoothly according to best practices.

This article does not focus on implementing an oil sampling program within an oil analysis strategy. Instead, it assumes the four key components are already in place and centers on effectively managing the oil sampling program to ensure it meets its intended objectives.

Below I introduce four performance metrics for managing an efficient oil sampling program, covering the process from sample extraction to receiving the oil analysis report.

These metrics include monitoring adherence to the sampling schedule, minimizing delays before sending samples to the lab, tracking the time from sample collection to lab delivery, and assessing the lab’s turnaround time for testing and report release.

Sampling Schedule Compliance

Sampling Schedule Compliance could be automatically obtained using a Computerized Maintenance Management System (CMMS).

In its absence, the calculation can be done monthly by dividing the number of oil samples drawn during the month (or oil analysis reports received) by the forecasted number of samples based on the established sampling frequency during the program implementation.

Oil Analysis Data Management Systems (DMS) have become a key element of the Oil Analysis Service offered by many labs today. A standout feature of these systems is the ability to create an oil sampling schedule and user reminders via email or notifications.

They also enable tracking the completion of scheduled sampling tasks. Additionally, there are various specialized software options designed for comprehensive lubrication management.

These solutions, whether from LAB DMS or commercial software, provide a valuable alternative, especially for smaller companies without a CMMS.

In his book Maintenance and Reliability Best Practices [2], Ramesh Gulati presented examples of maintenance and reliability benchmarks; the typical word class of schedule compliance is over 90%. Similarly, the minimum adherence for oil sampling PMs is 90%.

Waiting Time for Shipping

Through this metric, the objective is to measure the duration between the moment a sample is drawn from the equipment and when it is picked up for conveyance to the laboratory.

The waiting time for shipping can vary, ranging from zero to several days, depending on the contract between a company and its oil analysis service provider. Some companies opt for full outsourcing, including sampling, sample shipment, and analysis at the laboratory.

In such scenarios, the oil analysis lab or service provider delegates an inspector or technician to extract samples from the customer’s equipment and promptly transport them to the laboratory for analysis immediately after sampling.

In contrast, some companies simply extract and prepare samples from their equipment for collection. The sampler leaves the samples in the mailroom, and collection is handled by the lab or a specialized transport company.

Contracts may specify collection schedules based on sample quantity or batches. If sampling routes aren’t optimized to meet the minimum sample threshold, customers may delay shipment until more samples are collected or incur additional costs.

I recently came across a noteworthy example of effective coordination between a laboratory and a transportation company. In this arrangement, the lab has partnered with an international transportation company.

As part of this collaboration, the lab’s customers are granted access to the transportation company’s platform, allowing seamless sample pick-up scheduling. Undoubtedly, this service incurs a cost, but its tangible benefits significantly enhance the overall efficiency of the process.

In all cases, minimizing the waiting time for shipping is essential.

Shipment Time

This metric measures the time between collecting the sample from the site and physically receiving it at the lab facilities.

Several factors contribute to the delay in achieving the agreed-upon shipment time for oil samples, including customer-related issues, challenges associated with the transportation company, and unforeseen natural events.

Most oil sample transportation issues on the customer side stem from improper storage and packaging. Customers must ensure samples are securely sealed and properly packaged to prevent leaks.

Leaks can lead to various problems, including cross-contamination, loss of label identification, and insufficient sample quantities for analysis, ultimately affecting the sample’s representativeness.

Additionally, customers play a crucial role in speeding up the process by declaring that their oil samples have no commercial value and including Material Safety Data Sheets (MSDS) with the shipment. Omitting this vital information can result in significant delays at customs, especially for international shipments.

Transportation company-related factors also contribute significantly to report release delays. Strikes within transportation companies and unforeseen traffic accidents can disrupt the timely movement of samples from one location to another.

These incidents not only introduce unexpected delays but also exacerbate the challenges posed by customer-related issues.

Moreover, other external elements beyond the control of customers and transportation companies add another layer of complexity. Bad weather conditions, for example, can further impede the transportation process, causing delays in the arrival of samples at the analysis facility.

The interplay of these factors makes it crucial for companies to establish contingency plans and collaborate closely with reliable transportation partners to minimize disruptions and ensure more efficient and timely deliveries.

Laboratory Turnaround Time

Laboratory turnaround time refers to the duration elapsed from receiving the sample at the laboratory to releasing the report to the end user. This includes testing all relevant parameters, completing the diagnosis, and making the report accessible online or via email.

In certain instances, labs may issue a preliminary report while awaiting the completion of testing the full parameters requested. In this case, the laboratory turnaround time is to be measured from the initial reception of the sample until the delivery of the final report.

Various factors, including laboratory-related and customer-related challenges, contribute to the delays experienced in meeting the agreed turnaround time for report release.

Some laboratories lack automated equipment capable of processing multiple samples simultaneously, leading to inefficiencies in the analysis process.

Additionally, some labs may not be fully equipped to process the required analysis slate, necessitating the subcontracting of specific tests. This subcontracting introduces additional complexities and time constraints, extending the turnaround time.

Additionally, various operational issues within the laboratory can arise, such as equipment downtime, calibration difficulties, accidents, or shortages of solvents or reagents. Retesting, sometimes necessary for result validation, further delays the report generation process.

Challenges often stem from the sample registration process on the customer side. Delays can result from incomplete identification or poorly labeled samples, highlighting the need for precise and detailed documentation.

Leaks can also cause label erasure, requiring prompt communication with the customer to retrieve accurate information and maintain the integrity of the analysis results.

Many labs include mobile applications in their oil analysis service packages to address these challenges. Each sample bottle is given a unique code, entered at the moment of sampling using the mobile app. This allows instantaneous sample registration on the lab Data Management System (DMS) before the sample arrives at the lab registration desk.

When the bottle arrives at the lab, the bar code is entered into the Lab DMS, extracting all associated data. This streamlined process will allow the lab to reduce the time spent on sample registration and enable quick integration of samples into the workflow.

Why Should the Time Between Sampling and Lab Registration Be Minimized?

Retaining oil samples onsite for the required duration poses no issue if they are securely sealed, adequately packaged, and protected from contaminants such as water, dust, intense light, or radiation. Additionally, leaving sufficient ullage is essential for proper sample preparation and agitation, ensuring that any particles settled on the bottle’s surfaces are resuspended in the sample.

In these conditions, if the sample is representative initially, it will remain representative but representative of the existing oil in the equipment at the moment of sampling. This is similar to capturing a screenshot of equipment status and lubricant condition at the moment of sampling.

Prolonged waiting times before dispatching samples—and consequently, delayed reports—can hinder timely awareness, delaying interventions in response to rapidly developing potential failures. This is especially critical for key components operating in harsh environments with rapid changes, such as heavy-duty engines.

Using online sensors or establishing onsite oil analysis capabilities can deliver quick results but presents challenges related to detection limits, repeatability, and reproducibility. Even with reduced frequency, regular analysis at a commercial lab remains essential. However, minimizing the time between sampling and receiving the analysis report is critical.

References

[1] ISO 14830-1: 2019-12, Condition monitoring and diagnostics of machine systems – Tribology-based monitoring and diagnostics – Part 1: General requirements and guidelines, P 4.

[2] Maintenance and Reliability Best Practices, Second Edition, Ramesh Gulatti, Chapter 1, P 6.

Diesel engines are the driving force powering many modern transportation and industry applications. They can be found in vehicles and machinery, from trucks to marine vessels. In the port industry, diesel engines are found in Rubber Tire Gantry (RTG), Terminal Tractors, Reach Stackers, and other heavy mobile equipment.

Efficient engine function relies heavily on the combustion process that converts fuel into mechanical energy. High-quality combustion is crucial for optimal engine performance and overall reliability.

This article will not delve into the combustion reaction but into using engine oil analysis as a robust diagnosis and prognosis tool for monitoring combustion performance.

Oil Analysis: An Effective CBM Technique for Combustion Quality Monitoring

Oil analysis, as a CBM/PdM technique, is valuable for acquiring important information about the lubricant condition, wear, and contamination. It enables early failure detection, offering an opportunity for timely intervention.

Regular in-service engine oil analysis detects most of these issues as soon as they appear, often well before they become observable to the naked eye. With oil analysis data, maintenance managers or workshop supervisors can strategically plan interventions or conduct minor corrective maintenance actions instead of triggering a major intervention on the engine.

This article specifically addresses a singular aspect of engine oil contamination – namely, the suboptimal combustion by-products. Oil analysis is a valuable tool for identifying these by-products associated with poor combustion. It provides an opportunity to proactively address or mitigate the impact of:

Oil Degradation. Due to poor-quality combustion, the oil undergoes contamination from by-products of combustion or unburned fuel in the case of fuel dilution. These contaminants alter the physical and chemical characteristics of the oil and affect its performance properties.

Consequently, the oil fails to fulfill its lubrication and cooling functions. In the case of fuel dilution, the oil is thinned to the point where it cannot support the engine load or build a sufficient film to separate the moving parts. Additionally, poor combustion by-products act as catalysts for oxidation, enhancing oil degradation.

Engine Wear. Poor-quality combustion accelerates oil degradation. Therefore, the oil’s capacity to efficiently lubricate, cool, and protect the engine is diminished, increasing component stress and accelerating wear.

Decreased Engine Performance. Efficient combustion boosts the engine’s power output, providing better acceleration and overall performance. This efficiency ensures greater fuel conversion into usable energy, enhancing fuel efficiency. Conversely, poor combustion lowers fuel efficiency, increasing fuel consumption and operational expenses.

Safety Concerns. Fuel dilution lowers the oil’s flash point. When excessive fuel infiltrates the engine oil, it reduces the oil’s viscosity and increases its susceptibility to ignition. This presents a severe hazard, especially with the high engine temperatures.

Environment Pollution. Excessive soot emissions contribute to air pollution, as they contain harmful substances that can adversely affect air quality and human health. High-quality combustion reduces atmospheric emissions, contributing to environmental sustainability.

Tests Standards for Combustion Quality Monitoring

Two common indicators of incomplete combustion are fuel dilution and soot formation. There are many standards to help measure and monitor soot content and fuel dilution in in-service engine oils. Following are some essential tests for diesel engine combustion quality monitoring:

Soot Content

Soot, comprised of unburned combustion by-products, is found in oil as carbon, causing it to become thicker and darker.

Soot from diesel combustion is expected in an engine. No engine is 100 percent efficient. That’s why engine oil is doped with detergent/dispersant additives to enhance oil dispersancy.

Dispersancy is defined in ASTM D 7899 as the property that allows oil to suspend and carry away pollutants of diverse sources, such as soot from combustion, metallic particles from wear, corrosion of mechanical parts, and insoluble products resulting from the aging of the oil [1].

Excessive soot content signals potential issues with the components involved in combustion. These can be injection problems, prolonged oil drain intervals, low compression, high fuel/air ratio, and cold air temperatures.

Sometimes, elevated soot content is due to an excessive oil drain interval or operations practices like excessive idling.

Methods for testing soot in engine lubricating oil include:

• ASTM D7686, Standard Test Method for Field-Based Condition Monitoring of Soot in In-Service Lubricants Using a Fixed-Filter Infrared (IR) Instrument). This test method pertains to field-based monitoring of soot in diesel crankcase engine oils as well as in other types of engine oils where soot may contaminate the lubricant because of a blow-by due to incomplete combustion of fuels. It applies to oils having soot levels of up to 12% by mass [2].
• ASTM D7899, Standard Test Method for Measuring the Merit of Dispersancy of In-Service Engine Oils with Blotter Spot Method). This test method provides a simple technique for condition monitoring of the dispersancy property of in-service lubricants [1].
• ASTM D5967, Standard Test Method for Evaluation of Diesel Engine Oils in T-8 Diesel Engine, is a method for soot analysis by thermal gravimetric analysis.
• ASTM D7844-2 is the standard test method for condition monitoring of soot in in-service lubricants by trend analysis using Fourier Transform Infrared (FT-IR) spectrometry. This test method pertains to field-based monitoring of soot in diesel crankcase engine oils and other engine oils where soot may contaminate the lubricant because of a blow-by due to incomplete combustion of in-service fuels. This test method uses FT-IR spectroscopy to monitor soot buildup in in-service lubricants due to normal machinery operation. It is a fast, simple spectroscopic check for monitoring of soot in in-service lubricants to help diagnose the operational condition of the machine based on measuring the level of soot in the oil [3].
• ASTM E2412, Standard Practice for Condition Monitoring of In-Service Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry. This practice covers the use of FT-IR in monitoring additive depletion, contaminant buildup, and base stock degradation in machinery lubricants, hydraulic fluids, and other fluids used in regular machinery operation. Contaminants monitored include water, soot, ethylene glycol, fuels, and incorrect oil. Base stocks’ oxidation, nitration, and sulfonation are monitored as evidence of degradation [4].

These tests could directly confirm the presence of soot in engine oil, while other oil analysis tests play a contributing role in validating this issue. In this context, viscosity measured at 100°C for multigrade oils is a secondary test, as heightened soot content increases viscosity.

Additionally, elemental analysis can substantiate this degradation by evaluating the concentrations of wear metals resulting from inadequate lubrication as the oil undergoes degradation. Furthermore, as soot serves as an oxidation catalyst, oxidation levels and viscosity increase becomes apparent.

This confirms that oil analysis parameters are mutually complementary for a comprehensive and cohesive interpretation of oil analysis results.

Fuel Dilution

Fuel dilution occurs when the amount of unburned fuel in the engine oil increases. A high fuel dilution rate indicates an abnormal fuel passage into the oil. The predominant factor leading to fuel dilution involves infiltrating surplus fuel into the crankcase, which mixes with the engine oil.

With high fuel present in the oil, the lubricant’s viscosity becomes too low, reducing overall lubricating effectiveness. This phenomenon is often associated with raw or unburned fuel mixing with the oil resulting from incomplete combustion, worn injectors, or improper fuel/air ratio.

Sometimes, elevated fuel dilution could be due to operations like excessive idling.

The international standards to measure the amount of fuel present in oil include:

• ASTM D7593, Standard Test Method for Determination of Fuel Dilution for In-Service Engine Oils by Gas Chromatography.
• ASTM D 3524, Standard Test Method for Diesel Fuel Diluent in Used Diesel Engine Oils by Gas Chromatography. This test method uses gas chromatography to determine the amount of diesel fuel in used engine lubricating oil. It is limited to SAE 30 oil. The diesel fuel diluent is analyzed at concentrations up to 12 percent by mass. This test method may apply to higher viscosity grade oils. However, such oils were not included in the program used to develop the precision statement [5].
• ASTM E2412, Standard Practice for Condition Monitoring of In-Service Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry.

These tests confirm fuel dilution. Other oil analysis tests play a significant role in validating this issue. In this case, viscosity measured at 100°C for multigrade oils is a secondary test, as fuel dilution decreases viscosity. Likewise, reducing flash point serves as an additional means of confirming fuel dilution. Furthermore, a reduction in base number (BN) may indicate a significant fuel dilution.

Elemental analysis can also confirm this degradation by evaluating the concentrations of wear metals due to inadequate lubrication as the oil degrades. This analysis also provides helpful information about additive depletion.

Countermeasures for Poor Combustion Quality

Since poor combustion quality is connected with engine oil, to mitigate it, we should start by ensuring the fulfillment of the five’ rights’ of lubrication. First, we need to satisfy the Right Lubricant and Right Change Frequency. On the other hand, countermeasures to remedy poor quality involve supplying good fuel quality, checking air intake, and adjusting injection parameters. Consider these countermeasures:

• Lubricant Selection. Oils with low oxidation resistance tend to produce a precipitate more rapidly and in greater quantities than oil with high oxidation stability. Lubricants containing detergent and dispersant additives exhibit lower susceptibility to sedimentation because these additives enhance the capacity of the oil to retain insoluble impurities and resist oxidation more effectively. Make sure to use the appropriate lubricant and adhere to recommended oil specifications.
• Oil Change. A timely oil change is highly recommended. As detailed above, changing the oil as soon as possible is crucial, even for engines where soot contamination is detected without signs of wear. Soot can lead to complications over time.
• Air Filtration. A clogged or dirty filter can restrict airflow, affecting combustion. Inspect the air filter to ensure optimal combustion conditions.
• Fuel Quality. Fuel quality influences engine combustion. The heavier the fuel by fractional composition, the more it penetrates the crankcase. Adhere to recommended fuel specifications and use high-quality, clean fuel with the proper octane rating. This helps ensure a more efficient combustion process.
• Injection System Tune-up. Evaluate the air/fuel ratio and adjust the injection system to achieve a balanced mixture. Maintaining the correct air-fuel ratio is crucial for efficient combustion.
• Exhaust Monitoring: Monitor exhaust gases for evidence of incomplete combustion or unusual exhaust smoke. The presence of black smoke or a distinctive odor can indicate incomplete combustion.
• Operation Mode: The engine is most susceptible to inefficient combustion during light operation modes. These modes include minimal loads, low speeds, frequent and extended stops, and engine idling.

Case Study: Combustion Quality Monitoring for a Terminal Tractor Diesel Engine

Let’s explore a snippet from an engine oil analysis report of a terminal tractor with a cumulative operation time exceeding 110,000 Hours. During the criticality assessment, the terminal tractor diesel engine was identified as critical equipment.

An oil sample is drawn from this diesel engine every 500 running hours. The routine analysis slate includes the following parameters: Viscosity at 100°C, Base Number (BN), Water Content, Elemental Analysis, Fuel Dilution, Oxidation, Nitration, Sulfation, Glycol Content, and Soot Content.

Two oil analysis reports have been released so far. Given the focus on engine combustion efficiency in this case study, our attention in this oil analysis report will be directed towards associated with the monitoring of combustion quality, with a primary emphasis on Fuel Dilution and soot as primary tests for the engine combustion quality monitoring.

Additionally, viscosity and wear are serving as complementary tests. The table below provides a summary of these findings:

Analyzed by Gas Chromatography in accordance with ASTM D7593, the measurement of fuel dilution in both samples confirmed acceptable values, remaining below 2% by weight.

On the other hand, soot content in the first sample exceeded the acceptable range of 2 % by weight. However, no consequential increase in wear metals was observed, as their concentrations remain within acceptable limits.

In the second sample, there is a moderate concentration of iron, elevated Soot content, and high oil viscosity. These findings suggest a rich fuel mixture, generating soot that is highly abrasive and consequently contributing to engine wear.

The maintenance team has been advised to check the control points mentioned in the Countermeasures for Poor Combustion Quality section above. The feedback received confirms the satisfactory status of the requested inspections. This leads us to conclude that the elevated soot levels are primarily due to the extensive unit service time (+100,000 hours) and prolonged use of oil (+500 Hours).

According to the OEM, the oil should be replaced every 250 Hours. A subsequent sample will be drawn for condition monitoring and trending at the next scheduled interval. We expect to observe a notable reduction in soot levels and an overall enhancement in engine health.

References

[1] ASTM D7899-13: Standard Test Method for Measuring the Merit of Dispersancy of In-Service Engine Oils with Blotter Spot Method.

[2] ASTM D7686-19, Standard Test Method for Field-Based Condition Monitoring of Soot in In-Service Lubricants Using a Fixed-Filter Infrared (IR) Instrument).

[3] ASTM D7844-21 Standard Test Method for Condition Monitoring of Soot in In-Service Lubricants by Trend Analysis using Fourier Transform Infrared (FT-IR) Spectrometry.

[4] ASTM E2412-23 Standard Practice for Condition Monitoring of In-Service Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR) Spectrometry.

[5] ASTM D 3524-14 (2020): Standard Test Method for Diesel Fuel Diluent in Used Diesel Engine Oils by Gas Chromatography.

Wear monitoring is one of the primary objectives of oil analysis for predictive maintenance. Many oil analysis tests are considered suitable for wear debris analysis, and some, like elemental analysis and Wear Particle Index, are recommended within routine analytical slates.

Others, like Analytical Ferrography, are only requested occasionally and are typically reserved for in-depth investigations whenever required.

Elemental Analysis

Elemental analysis is a part of almost all routine oil analysis test slates across many applications. It is a cornerstone of lubricant analysis and a powerful ally for wear detection at early stages.

Inductively Coupled Plasma (ICP) or Rotating Disc Electrode (RDE) are the most common analysis methods for conducting elemental analysis for used lubricants, and they are performed respectively per ASTM D5185 and ASTM D6595.

Elemental analysis is a standard method used to determine quickly and in one single measurement the concentration of various elements within an oil sample.

It identifies and quantifies at low parts per million (ppm) concentrations for at least 21 elements: Iron (Fe), Copper (Cu), Aluminum (Al), Chromium (Cr), Nickel (Ni), Lead (Pb), Silver (Ag), Tin (Sn), Silicon (Si), Sodium (Na), Potassium (K), Magnesium (Mg), Calcium (Ca), Phosphorus (P), Zinc (Zn), Boron (B), Molybdenum (Mo), Titanium (Ti), Vanadium (V), Barium (Ba), Sulfur (S).

Oil analysis professionals can monitor the levels of wear metals, additives, and some contaminants through elemental analysis. This helps assess the condition of oil and equipment and identify potential issues, such as contamination, additives depletion, or excessive wear.

However, it is essential to acknowledge the inherent limitations of elemental analysis. The ICP technique can detect elements accurately (with high repeatability) if the elements are below five microns in size, with repeatability tailing off for particles approaching and exceeding seven microns.

The RDE technique also provides confidence for detection up to a five µm size range, with detectability tailing off as particles exceed 10 microns. For RDE and ICP techniques, particle size visibility can vary by element type, such as copper and chromium.

While the accuracy of the analysis can be influenced by factors such as sample handling and instrument calibration, these techniques (ICP and RDE) are considered the preferred means for routine wear debris assessment for commercial labs.

Considering these constraints, most laboratories complement elemental analysis with additional test methods that detect particles beyond the incipient wear range (>5 µm size).

In the context of gearbox oil analysis, techniques like Particle Quantification and Ferrographic Analysis are complementary tools that provide a more holistic approach to monitoring gearbox condition.

Ferrous Density Analysis

The most prevalent and affordable method for assessing ferrous density is Particle Quantification Index (PQI), also known as Wear Particle Index (WPI).

This test directly quantifies the magnetic mass of ferrous debris in the oil sample, regardless of particle size and shape. It provides a non-dimensional value representing the total amount of the existing ferrous debris in the sample.

PQI is a powerful tool for wear detection, monitoring ferrous particles larger than the elemental analysis detection range.

In this regard, PQI is an invaluable complementary test to elemental analysis.

Performed per ASTM D8184, Particle Quantifier Index is recommended as a routine test for all types of industrial, mining, shipping, and aviation equipment.

Direct Read Ferrography (DRF) is another cost-effective technique for characterizing the wear concentrations of larger-size particles.

By leveraging the magnetic susceptibility of particles, DRF enables the calculation of the Wear Severity Index based on a direct reading of both large and small particles. Consequently, DRF can serve as a suitable alternative to PQI.

Analytical Ferrography

It is helpful to understand the underlying reason (the wear mode) whenever elemental analysis, PQ Index, or DR Ferrography indicates the presence of an elevated wear metal concentration. In these circumstances, it is helpful to ‘see’ what is occurring inside the machine.

Analytical Ferrography is a powerful and proven qualitative technique that utilizes a microscope to examine wear particle appearance, including the color, size, and shape of particles in the oil sample, to determine the different wear modes and the possible sources of wear debris.

The results are provided per ASTM D7684 and are complemented by photos, allowing the comments to be visualized. Given the time and expertise required to perform the diagnosis, its cost is relatively high.

Accordingly, it is conducted as a secondary test when other lower-cost methods have strongly indicated a problem.

With routine testing, the oil sample is drawn from the primary sampling location and represents the whole system. Secondary sampling locations close to the components should be utilized if a machine has multiple branches or subsystems.

These samples will reveal the highest concentration of wear metals and the likely source of the wear and failing components.

Given the above information, a well-designed analysis slate includes elemental analysis and Wear Particle Index as essential elements. When further investigation is needed, conduct Analytical Ferrography.

Please note that using permanently located oil sampling ports will yield the most representative results.

For a deeper investigation, oil analysts may opt for Filter Debris Analysis. This analytical technique involves examining debris and particulate matter captured within oil filters, which are explicitly designed to trap solid particles, wear debris, and sometimes even water contaminants.

Analysts can find critical clues about the types of wear occurring in the equipment by carefully scrutinizing the composition, size, shape, and quantity of particles in the oil filter.

By understanding the origins of these particles, maintenance teams can take proactive measures to rectify issues, prevent further damage, and extend the lifespan of machinery.

Case Study: Gearbox Condition Monitoring through Iron Content, Wear Particle Index, and Analytical Ferrography

The table below provides the oil analysis results of two samples drawn from a gearbox in the port industry. This case study focuses on the wear metals concentration data acquired through ICP and Particle Quantification Index.

Additionally, the Analytical Ferrography analysis was conducted only for the second sample, promptly following the release of the report of the first sample. All the other parameters are satisfactory, including Viscosity at 40°C, Total Acid Number, and Water Content.

A notably elevated PQ Index compared to the iron concentration detected by ICP has led us to deduce that there has been an accumulation of large ferrous debris within the oil sample, reaching notably high levels. This finding prompted consideration of abnormal wear phenomena inside the gearbox.

This could be attributed to various factors like the ingress of abrasive contaminants, suboptimal lubrication, misalignment issues, or excessive mechanical loading. It should be investigated further.

In this situation, maintenance personnel were asked to draw an urgent representative sample to confirm these abnormal results because this was the inaugural sampling for this gearbox.

One oil analysis report should never be used as the basis for a decision involving replacement or immobilizing equipment.

In addition to the routine analysis slate, Analytical Ferrography was requested. The lab was notified of the emergency and was asked for a quick turnaround.

Simultaneously, maintenance personnel checked the operating conditions of the gearbox, verifying the OEM-recommended parameters, the load, the speed, and the operating temperature.

They were also asked to assess alignment and vibration. Considering other non-destructive inspection techniques to confirm findings is recommended in these situations before embarking on any potentially expensive decision or action.

These combined actions are essential to promptly address and rectify any potential issues within the gearbox and provide a supporting finding. They will serve as crucial inputs for Root Cause Analysis once the lab releases the oil analysis report.

When the second sample report was received, the PQ Index result was confirmed high, and the iron content was relatively the same as the previous sample.

The Analytical Ferrography examination revealed the presence of several types of particles, including those attributed to Normal Rubbing Wear, Fatigue Chunks, Laminar Particles, Corrosive wear debris, Dark Metallo-Oxides Particles, Non-Metallic Crystals, Friction Polymers, and Fibers. Below is a compilation of potential sources of these particles:

1. Rubbing wear particles indicative of normal rubbing wear.
2. Friction polymers can be attributed to excessive mechanical load or stress on the lubricant.
3. Fatigue chunks, suggestive of abnormal periodic machine vibration.
4. Laminar particles are suggestive of a rolling contact failure.
5. Dark Metalo-Oxides, potentially resulting from high operating temperature and/or suboptimal lubrication conditions.
6. Fibers that may have entered the gearbox during maintenance or been introduced to the sample during its extraction.

These insights into the origin of the detected particles are invaluable for understanding the underlying factors contributing to the observed wear patterns. This case study is a concrete example of how combining wear debris analysis techniques is essential for gearbox condition monitoring.

By implementing this proactive approach, equipment managers can maintain high levels of equipment uptime and prevent costly breakdowns.

Oil analysis success hinges on the quality of the oil sample. Drawing a representative oil sample involves a combination of factors, including selecting the right location, deploying the right method, using the right hardware, determining the right sampling frequency, and providing relevant and accurate labeling.

This article is dedicated to the process of oil sampling using vacuum pumps. We will explore the steps in conducting successful oil sampling with a vacuum pump, shed light on the complexities and challenges surrounding this critical task, and suggest some tips to overcome these limitations.

The Importance of a Representative Sample

Before we dive into the specifics of vacuum pump oil sampling, let’s review why representative oil sampling is essential.

To ensure the data derived from oil analysis is reliable and actionable, the collected samples must accurately represent the condition of the entire system. This brings us to the primary concerns of maximum data density and minimum data disturbance.

The ISO 14830 standard states that maximum data density is the most possible information contained per sample unit volume [1]. This implies that the sample must have a sufficient concentration of all existing kinds of contaminants, wear debris, and other analytes of interest.

The density ensures that any abnormalities or deteriorations in the equipment can be detected early, allowing for proactive maintenance.

On the other hand, the same standard says minimum data disturbance is when information is uniform, consistent, and unaltered by the process [1]. Using permanently installed sample ports is always best to avoid data disturbance. Variability (data disturbance) can occur whenever a permanently installed sample collection port, including drop tube and drain port sample collection, is not used.

Oil Sampling Techniques

There are typically three available options for drawing an oil sample from machinery or equipment:

Sampling Valve

Not all equipment has a sampling valve installed correctly in a turbulent zone in the return line before the filter. Some machines are equipped with sampling valves which offer a reliable and convenient way to draw a representative oil sample.

Otherwise, evaluate equipment design and consider retrofitting with sampling valves or creating better access points to facilitate sampling. For future equipment orders, during the design phase, and when building specifications, consider future oil sampling and request that the OEM install a sampling valve in the best possible location.

Drain Valve

The drain valve can be used if the equipment does not have a sampling valve installed. But this is the least recommended sampling location. It is impossible to ensure that the extracted oil sample is representative, as the oil at the bottom may differ in composition from that higher up in the reservoir.

The only option to ensure drawing a representative sample from the drain valve is to use a drain port adapter that places a formed steel tube into the correct location in the reservoir. Thus, in addition to the drain, the drain valve will ensure a second function: getting an oil sample from a desired location inside the reservoir.

Vacuum Pump

In case there is no sampling valve located in a turbulent zone, or it is not practical for use due to obstructions or safety concerns, a drop tube with a vacuum pump can serve as a marginal alternative to extract the oil sample. This sampling technique offers the ability to get the oil sample from various locations within the equipment.

However, knowing the data disturbance constraints linked to this method is crucial. In the subsequent sections, we discuss how to use a vacuum pump to draw a representative oil sample from equipment and explore how to mitigate potential errors when using this method.

Process for Vacuum Pump Oil Sampling

Oil sampling with a vacuum pump involves a series of steps to ensure that the collected sample is representative and uncontaminated.

The best possible sample result using a sample gun (vacuum pump) is achieved by installing an internal ‘pitot’ tube to ensure that the sample entering the sample bottle is always precisely from the same location within the machine. The image below demonstrates what the installation should look like upon completion.

The end of the tube should be at a minimum of 75 millimeters/3 inches above the bottom and away from a vertical sump wall. If possible, permanent tubes should also be formed so that the internal pipe opening is placed in the dynamically moving body of oil within the machine.

Before starting the oil sampling procedure, gather all necessary tools, including a vacuum pump, sampling bottles, suction tube reel, gloves, and all required PPEs. Begin by inspecting the vacuum pump to ensure it is clean and in good working condition. Any contamination present on the pump could introduce errors into the sample.

Once the preliminary preparation is completed, the following steps apply to various scenarios: splash-lubricated gearboxes, bath-lubricated equipment, and reservoirs.

• Step 1: Ensure the equipment to be sampled is in operation or has recently been operated to collect a representative sample. Equipment should have been operated in its typical working conditions (temperatures, loads, pressures, speeds, and level) for at least one hour before extracting an oil sample. Samples should not be taken when the equipment is cold, idle, or has not been running. Additionally, avoid lubrication starvation by checking the oil level indicator and confirming it is at the required level when drawing the sample.
• Step 2: Identify the sampling point and ensure it is clean and accessible. The sample point could be the filling point, the breather, or the dipstick. Clean the sample point with a lint-free cloth. Taking a routine sample from the same location each time is highly recommended to guarantee consistent sampling.
• Step 3: Cut the new sample tube to the desired length, ensuring that the tube length allows the vacuum pump to be horizontal during sampling. The drop tube length should be the same every time you take a sample.
• Step 4: Insert the sample tube into the metallic disk on top of the vacuum pump so that the tube extends approximately ½ inch from the bottom and tighten the metallic disk to secure the tubing.
• Step 5: Remove the waste bottle cap and affix the bottle to the vacuum pump to ensure drop tube flushing.
• Step 6: Insert the tubing into the sampling point cautiously, being vigilant to prevent the tube from touching any surface or internal components, such as gears, in the case of a splash-lubricated gearbox. Ensure that the tubing reaches the desired depth within the equipment, positioning the tubing tip at the midpoint of the existing oil volume in the reservoir.
• Step 7: Start the vacuum pump to create a controlled vacuum within the sampling container and the tubing by pulling the pump handle 1 to 3 times. Allow the sample bottle to fill to the ullage mark. There is no need to keep pulling the handle.
• Step 8: Discard the waste bottle and connect the vacuum pump to the sampling bottle. The lid should be kept sealed until ready for use to prevent contamination of the oil sample. Ensure the sample bottle is appropriately labeled and matches the sample ID tag on the equipment sampling location.
• Step 9: Operate the vacuum pump to draw the oil into the sample bottle, ensuring that the bottle is filled to the recommended level, which varies depending on viscosity. Once the desired sample volume is achieved, use the pressure relief button on the sample gun or loosen the bottle to release the vacuum and stop the flow.
• Step 10: Remove the sample bottle from the pump and securely seal it to prevent contamination.
• Step 11: Take the used sample tubing out of the pump and dispose of it properly. Do not reuse the tubes.
• Step 12: Use a clean, lint-free cloth to wipe down the vacuum pump, removing any trace of oil. Ensure that any spilled lubricant is cleaned up thoroughly.
• Step 13: Complete the sample label and documentation with relevant and essential information. For a more in-depth understanding of sample identification best practices, refer to the article: Oil Analysis Blunders: How to Avoid Mistakes in Sample Identification, which offers comprehensive insights.
• Step 14: Package the sample to prevent contamination and store it in a clean and secure container for safe transportation to the laboratory.

It is highly recommended to have a specific Standard Operating Procedure (SOP) for each machine monitored by oil analysis. This SOP should be documented and followed each time by all members of the oil analysis team.

Limitations of Vacuum Pump Sampling

While vacuum pump oil sampling is an alternative when well-located sampling fittings are not installed, it has limitations. There are several challenges, including:

Questionable Cleanliness

The vacuum pump-based sampling method requires, in addition to the vacuum pump itself, a suction tube and plastic bottles. All three components must be handled carefully to maintain integrity and prevent contamination. The vacuum pump should be securely protected within a plastic bag to ensure this.

The same level of protection should extend to the drop tube reel and the plastic bottles. Furthermore, these containers must remain sealed and unopened until the precise moment they are needed for sampling. Unfortunately, it is common to overlook the proper storage conditions of the sampling kit.

 The objective of the fifth step of the procedure outlined above is to remedy this neglect by using a waste bottle to flush the internal steel (pitot tube) and external plastic suction tube before collecting the sample to be analyzed.

Unfortunately, sometimes maintenance personnel don’t understand the importance of thoroughly flushing the sample pathway and collecting the sample without flushing. This oversight can affect the cleanliness and reliability of the obtained samples.

Questionable Consistency

Consistency in sampling means that the oil sample is extracted from the same location using the chosen method at each sampling operation.

With the vacuum pump technique, the sampling personnel inserts the suction tube into the reservoir, typically through a breather port, and even if they precisely measure the needed length of the tube and insert it as required, this does not guarantee repeatability and optimum results.

Without exceptional attention to detail, it is tough to ensure that the flexible plastic tube reaches the exact and desired location to collect the oil sample. This depends on the quality of the plastic tubing, its length, and the oil temperature.

When a ‘fixed sample port’ installation is impossible, the drop-tube sampling process should be enhanced to ensure that the tubing consistently reaches the desired sump depth and location. This can be done by affixing the sample tube to a rigid item like a rod or attaching a weight to the tube.

Be sure to rinse the rod or weight before and after each use. Use a solvent and allow it to evaporate at room temperature. This precautionary measure helps to avoid cross-contamination and maintains the integrity and reliability of the sampling process.

Contamination Likelihood

To extract an oil sample using a vacuum pump, we typically need to remove breathers, dismantle filters installed in the filling points, pull the dipstick, or even sometimes open manholes. Although these actions are performed with meticulous care and respect for established procedures, contaminants can always get in during sampling, particularly with wind or rain. Consider cleaning the sampling location properly with a clean rag and deploy protective measures for equipment installed in an uncovered area in case of bad weather.

Motorized Oil Sample Vacuum Pumps

Integrating a battery motor-driven vacuum pump into your oil sampling program is a strategic investment for monitoring lubricant and equipment health. With prices starting as low as $100, these motorized vacuum pumps can bring a cost-effective solution to the oil analysis team that can yield substantial benefits.

Many advantages include enhanced service levels, improved efficiency, and heightened overall effectiveness. These benefits stem from the user-friendly features of motorized vacuum pumps, such as their convenience, robust design with a one-handed grip, and the simplicity of a one-touch operating switch.

The integrated speed control valve allows for precise adjustments in sampling speed, making it adaptable to various scenarios, even in confined spaces.

Moreover, this technology enables efficient sampling with a single worker, reducing labor requirements and increasing productivity. The speed and efficiency of the process are further highlighted by the rapid sampling time, making motorized vacuum pumps an exciting tool for those committed to monitoring the health of their lubricants and equipment.

In conclusion, a repeatable and representative oil sample is the foundation of a practical oil analysis for predictive and condition-based maintenance. Analysis results interpretation is only valid if samples are collected in a repeatable manner and are representative of the lubricant under operating conditions.

Errors in obtaining samples impair all further analytical efforts [1]. Central to a representative oil sample is achieving maximum data density and minimum data disturbance. By mastering drawing oil samples with vacuum pumps while acknowledging their limitations, maintenance professionals can ensure that their oil sampling process is reliable to achieve oil analysis program objectives.

 References

[1] ISO 14 830-1:2019: Condition monitoring and diagnostics of machine systems — Tribology-based monitoring and diagnostics — Part 1: General requirements and guidelines.

Industry professionals and lubrication practitioners know the crucial role of proper lubricant selection in ensuring equipment operation efficiency. To help in this process, Lubricant Technical Data Sheets (TDS) serve as an essential resource.

Whether conducting a lubricants consolidation study or performing a lubricant compliance check, TDS provide maintenance engineers with the information to make informed decisions regarding lubricant selection and maintenance.

What Is a Lubricant Technical Data Sheet?

A TDS is a one- or two-page document provided by lubricant blenders that contain technical information and performance details about the lubricant. TDS has other names, like Product Data Sheet or Product Information.

Understanding the content of a lubricant TDS can help accomplish the following objectives:

Proper Lubricant Selection

As detailed in the next section, Lubricant TDS clearly explains the lubricant’s physical and chemical characteristics and performance capabilities. This knowledge allows for a better alignment between lubricant properties and the desired equipment performance, such as improved corrosion protection, enhanced fuel efficiency, or high load-bearing and surface (extreme pressure) capability.

This enables users to make informed decisions to select lubricants of a certain quality level most suitable for their equipment and operating conditions. Furthermore, if applicable, TDS allows users to ensure that the lubricant meets recognized industry standards, requirements, and OEM approvals.

This knowledge minimizes the risk of using an unsuitable lubricant. Using the right lubricant reduces the risk of compatibility issues, mitigates potential warranty-related concerns, enhances equipment performance, and extends its useful life.

Equipment Health Condition Monitoring

The lubricant is a chemical product. Lubricant physical and chemical properties degrade over time, under the effect of operations and environmental conditions. The lubricant TDS can be used as a valuable troubleshooting tool by checking in-service lubricant condition against initial values included within its respective TDS.

Additionally, in case of lubrication-related issues or equipment failures, TDS can help identify potential causes by cross-referencing the lubricant’s properties and performance characteristics. This facilitates faster problem resolution, minimizing downtime and reducing associated costs.

Regulation and Industry-Specific Standards Compliance

Certain industries have specific regulatory requirements for lubricants. For example, lubricants must meet strict health and safety standards in Food Processing Industry. TDS helps to quickly check that lubricants comply with these regulations.

On the other hand, TDS may highlight any environmentally friendly features of the lubricant, such as biodegradability or eco-label certifications. This information is vital for applications where environmental compliance or sustainability is a priority.

What Is on Lubricant Technical Data Sheets?

There is no standard for lubricant TDS, and they can typically be divided into various sections:

Generalities

Lubricant TDS typically begins with key elements for product identification, including its brand, name, and product code, if any. This allows easy identification and differentiation of a lubricant among various available lubricant options.

Additionally, this section of generalities includes a description of the product and some details about its blending formulation, including an overview of performance additives and the lubricant benefits.

The TDS also details specific applications where the product is intended to perform optimally: Equipment Type, Equipment Design, Operating Speeds, Temperature Ranges, and environmental factors—all this obviously with some cosmetics from marketing people.

Typical Lubricant Properties

Understanding the lubricant properties helps determine the lubricant’s suitability for specific applications and operating conditions. Accordingly, TDS includes laboratory measurements performed on the batch of product and provides crucial insights into the testing results of various physical and chemical parameters and performance tests.

• Physical Parameters: Lubricant TDS usually includes test results for a range of physical parameters that provide users with a comprehensive understanding of the lubricant’s physical properties. This information is needed to help determine the suitability of use for specific machine operating conditions. Some common physical parameters found in TDS include Viscosity measured at 40°C or 100°C, Viscosity Index and Density measured at 15°C or 20°C.
• Chemical Tests: Lubricant TDS typically includes many chemical test results or information that provides users with some insights into the performance characteristics of the lubricant. These chemical parameters help determine the lubricant’s stability and protective capability for common machine materials. Rust and Corrosion Protection and Oxidation Stability are chemical test performance data examples.
• Performance Tests: Lubricant TDS sometimes includes information about various performance parameters. These parameters highlight the lubricant’s ability to meet specific performance requirements and give users insights into its effectiveness in different applications. Under the umbrella of performance tests, we may find Load-Carrying Capacity, Friction Characteristics, and Wear Protection test data.

Example of how lubricant properties are provided within a lubricant TDS:

We cannot conclude this discussion on lubricant characteristics without highlighting that the specific performance parameters and their respective test results in the lubricant TDS may vary depending on the lubricant type, application, and manufacturer.

Further, where these standardized test results are lacking, it is reasonable to ask the lubricant vendor to provide these critical data points from unpublished internal resources.

Lastly, multiple petroleum performance test labs can be hired to supply or verify test result claims found on the TDS. Individual performance testing is typically not expansive.

Specifications and Approvals

Specifications and Approvals are critical in ensuring that the lubricant meets the required quality and performance standards, thereby supporting optimal equipment performance. In some Lubricant TDS, specifications and approvals are merged in one section.

In these sections, Lubricant TDS outlines the performance specifications and industry standards that the lubricant complies with. Approvals from OEMs and industry certifications further assure that the lubricant is specifically formulated and has undergone rigorous testing.

It meets specific performance criteria to ensure the machinery’s performance capability and adherence to specific requirements. These specifications and approvals can be set by various organizations, such as international standards bodies or industry associations, including:

Disclaimer

In a separate section or included within every other section, disclaimers and warnings are considered important content provided by lubricant blenders about their product. It addresses restrictions and limitations and asserts that the provided information is based on the manufacturer’s current knowledge and experience.

It highlights that users should conduct their own assessments and tests to determine the lubricant’s suitability for their specific application(s). The disclaimer may also indicate that the manufacturer is not liable for any damages or losses resulting from using the lubricant based on the information provided in the TDS.

What Are the Limitations of a Lubricant Technical Data Sheet?

While Lubricant TDS provides valuable information about lubricants, it is essential to be aware of their limitations. Understanding these limitations helps users make informed decisions and ensures that TDS are used as a helpful tool rather than a sole determinant. Here are some lubricant TDS limitations to consider:

Generalized Information Vs. Required Customization and Specification

The information contained within a lubricant TDS is general. It may not address every specific requirement or operating condition. Users are urged to conduct additional laboratory tests to verify the lubricant’s suitability to their particular lubrication context. They should consult lubrication experts or refer to the lubricant supplier’s technical support for specific application guidance.

Lubricant Quality Control Vs. Long-Term Performance

Lubricant TDS provides information based on blending plant laboratory tests within the quality control process. It may not provide comprehensive data on the lubricant’s long-term performance or aging characteristics.

This way, Lubricant TDS focus on the lubricant itself and may not address external factors that can influence performance, such as equipment maintenance practices, contamination levels, or operating conditions.

Users should consider external factors, conduct additional tests or refer to experts and benchmarks to gather more insights about the lubricant’s performance within the operating context.

Legal Disclaimers

Lubricant TDS typically includes legal disclaimers that limit the liability of the lubricant manufacturer for any damages or losses resulting from using the lubricant. Users should be aware of these disclaimers and understand they assume responsibility for applying, using, and testing the lubricant in their specific circumstances.

In conclusion, lubricant TDS are part of a comprehensive lubrication strategy. This article aims to share guidelines to navigate the information presented within a lubricant TDS and gain insights into the critical aspects of lubricant selection and maintenance.

By understanding the significance of each section and its implications on lubricant performance, lubrication professionals can make well-informed decisions that align with their specific lubrication requirements. Thus, they will be empowered to optimize equipment performance and extend their useful life. One rule of thumb is to consider Technical TDS limitations as well.

Conducting additional tests, seeking guidance from lubrication experts, and considering application-specific factors are essential for ensuring optimal lubricant selection and maintenance.

They are used to lift and pull heavy containers in Ship-To-Shore Cranes (STS), Rubber Tyre Gantry (RTG), and Straddle Carriers. I can also see them on my way to work in different construction machines, and I feel their usefulness when I use the elevator of the building where I live.

But they are not only used in handling heavy loads! They also serve as structural support cables in large static structures like The Mohammed VI Bridge, the longest cable-stayed bridge in Africa, linking the capital city of Rabat to the city of Salé.

Getting optimum life out of dynamic steel wire rope is one of the key strategies within a maintenance program. A simple discussion with maintenance folks in the field will reveal that wire ropes are a big issue. In this article, I will not dwell on dimensional characteristics but focus on the lubrication side of dynamic steel wire ropes.

I will explore how to keep dynamic steel wire ropes youthful through relubrication, starting by shedding light on the importance of relubricating dynamic steel wire ropes, then reviewing the types of lubricants used. This article concludes with different possible methods to relubricate dynamic steel wire ropes and the best practices for effective dynamic steel wire rope relubrication.

Why Is Lubricating Dynamic Steel Wire Rope Required?

Adequate and proper lubrication is vital to keeping dynamic steel wire rope running at its best. DIN 15020 standard explains that lubricants in wire rope diminish friction and corrosion between the groove and the wire rope and between the individual wires.

The same standard explains that shorter rope service life should be expected if the wire rope lubrication is stopped for operational reasons. Thus, lubrication is essential in the steel wire rope life cycle.

It considerably impacts its operability and aims to support the integrity of the wire ropes with continued safe and effective operations. Lubrication could eliminate or minimize most of the causes of wire rope failures. We can segregate between 3 tiers for steel wire rope lubrication:

Lubrication Of Dynamic Steel Wire Rope During The Manufacturing Process

Individual steel wires are subjected to extensive bending, twisting, and tension during their manufacturing process to form the rope. These actions generate friction between the individual wires and strands, leading to wear and potential damage.

The lubricant helps the wires move smoothly through manufacturing machines. Also, it helps create a protective layer between the wires to allow slight movement between them and minimize the risk of wear and corrosion. ISO 4346 Standard specifies the nature, properties, and basic requirements of lubricants used to manufacture wire ropes for general purposes [2].

Lubrication Of Dynamic Steel Wire Rope During Storage

Dynamic steel wire ropes depart the manufacturing plant saturated in lubricant. During their storage, wire ropes can be exposed to several factors affecting their performance and longevity after deployment.

Direct exposure to rain or snow, humidity, temperature changes, and chemicals increases the risk of corrosion before deployment. Proper lubrication is essential in protecting their structural integrity and readiness for use.

Regular wire rope inspections during storage can help determine when relubrication is necessary. Signs of wear, corrosion, or excess dirt and debris may show the need for relubrication.

Additionally, wire ropes stored for an extended period without use may require relubrication to ensure they are still in optimal condition before installation. If necessary, apply a suitable preservative or lubricant compatible with the rope manufacturing lubricant [3].

Lubrication Of Dynamic Steel Wire Rope In Service

During operations, a steel wire rope is bent considerably. The wires and the strands move against each other. Relative movements also occur between the wires in stranded ropes changing the tensile forces by friction. There are also movements between wire ropes and sheaves [4].

On the other hand, steel wire ropes must withstand demanding working conditions (heavy loads, constant friction) and harsh environments (exposure to dirt, chemicals, moisture from rain or high humidity, and other contaminants). These factors can cause the wire rope to deteriorate over time, leading to loss of strength, wear, and eventual failure. Lubrication helps to minimize the effects of these factors by:

• Reducing internal (metal-to-metal contact between wires and strands) and external friction (wire rope exterior surfaces with grooves).
• Enhancing flexibility.
• Mitigating fatigue failure.
• Protecting from external contaminants.
• Preventing Corrosion.

What Is the Right Lubricant For Dynamic Steel Wire Rope Relubrication?

To make dynamic steel wire rope conduct its duty smoothly while being protected from external contamination and corrosion, consider two categories or types of lubricants: penetrating and surface coating lubricants.

Penetrating Lubricant

Dynamic steel wire ropes may fail from the inside with regular use. Penetrating lubricants are intended to reach the steel wires in the strands and rope core to reduce friction and wear during normal use and provide maximum protection against corrosion. Desired properties for penetrating lubricants are:

• In grease, suitable consistency, drop point, thickener, and base oil viscosity with friction modifiers additives (AW & EP).
• In the case of oil, suitable base oil viscosity with desired additives (AW & EP).

In both cases, the lubricant should withstand the elevated temperatures generated during wire rope operation and have excellent water and oxidation resistance.

Coating Lubricant

The coating lubricant should act as a barrier and seal to protect the outside of the wire rope from moisture and contaminants. Desired properties of coating lubricant are:

• Corrosion prevention
• Resistance to hot temperatures and water/wash
• Sufficient adhesive strength to allow the lubricant to remain on the rope

It is advisable to avoid asphaltic compounds because they dry into a dark hardened surface that makes inspection and cleaning difficult.

Several lubricating products can be used to relubricate dynamic steel wire ropes, including greases, oils, and dry lubricants. The choice of lubricant will depend on the application, environment, and operating conditions.

When selecting a lubricant for dynamic steel wire rope, make sure it complies with the recommendation of the steel wire rope manufacturer.

What Is the Right Quantity of Lubricant To Use While Relubricating Dynamic Steel Wire Rope?

The amount of lubricant applied is critical. Over-lubrication can lead to excess buildup and attract dirt and debris, while under-lubrication will not adequately protect the wire rope and lead to increased wear. Following the manufacturer’s recommendations, applying the right lubricant amount can help ensure optimal lubrication and wire rope protection.

Relubrication Intervals for Wire Ropes

After the wire rope is put into service, the original lubricant is lost gradually with normal use. Regular relubrication is essential to ensure the wire rope’s longevity. However, the relubrication frequency is difficult to manage as it depends on various factors, such as the application and operating conditions, including load, speed, and environment.

With wire rope relubrication, we should differentiate between coating lubrication and penetrating lubrication. The coating lubrication frequency follows the inspection frequency. Before visual or magnetic inspection, the wire rope should be cleaned (remove the coating lubricant). After the wire rope inspection, the coating lubricant should be re-applied.

However, as a rule, dynamic steel wire rope relubrication intervals should be scheduled per the wire rope manufacturer’s recommendations and the equipment manufacturer where it is installed. Without such instructions, lubricate wire ropes for benign operating conditions at least once a year.

More frequent lubrication would be necessary for severe operating conditions and environments to maintain optimal performance and prevent wear and corrosion.

Methods to Relubricate a Wire Rope

Relubricating wire ropes should be preceded all the time by cleaning. Any residual coating lubricant and contaminants should be removed first before applying any new lubricant. There are three common methods for wire ropes lubrication: [6]

Manual Lubrication

Manual lubrication involves applying the lubricant to the wire rope by painting, Swabbing, or brushing. It is typically used only for coating outer wires and is suitable for wire ropes not exposed to elevated temperatures. When using oil, a spray can be used for the wire rope relubrication.

Manual Lubrication (painting) of wire ropes is time-consuming and poses safety and environmental issues. Technicians come into close contact with lubricants and may have some safety concerns due to broken strands and intensive labor.

Additionally, manual lubrication will use more lubricant than other methods, probably resulting in poor lubricant penetration. The more lubricant quantity used, the greater the lubricant cost and risk of environmental impact.

Semi-Automatic Technique

The drip, spray, or trough method can apply the lubricant. These methods apply the lubricant at a single point and use the rope’s movement to spread the lubricant over the entire length of the system.

Automatic Technique

Pressurized lubricant application is the best relubrication method for wire ropes. This approach utilizes a pump, the force of the pressurized lubricant between the wires and into the wire rope’s small vacant spaces.

This mode provides maximum penetration of the lubricant into the gaps of the wire rope, enables the lubricant to adhere to each wire, and offers the best protection against corrosion. Side benefits from the pressurized application include less safety risk to technicians and less chance of environmental impact from routine care.

Best Practices for Wire Rope Lubrication

To ensure adequate dynamic steel wire rope lubrication, follow these best practices:

Do’s

Lubricant Compliance

Use the right lubricant suitable for the wire rope material and application. Consider the factors mentioned above and follow recommendations from the wire rope manufacturer to ensure compatibility and effectiveness.

Cleaning Before Relubrication

Before applying the lubricant, clean the wire rope thoroughly to remove any dirt, debris, or any other contaminant from the outer strands and in the valleys of the wire rope. A wire rope cleaner could be used. This will enable a proper penetration of the new lubricant and enhance the corrosion protection to optimize wire rope lifespan.

In case of dirty wire rope, hardened lubricant, or accumulated layers of the old lubricant or other contaminants, the wire rope should be cleaned with a wire brush and petroleum solvent, compressed air, or steam cleaner before relubrication. For this, use only compatible cleaning fluids, which will not impair the original rope lubricant nor affect the rope-associated equipment.

Lubrication Method

Use the wire rope lubrication proper method, which will facilitate the application of the lubricant evenly over the wire rope full length.

If the lubricant contains a diluent that evaporates after exposure to the atmosphere, the lubricant should be given 4 to 8 hours to ‘cure’ before the device is returned to service.

Safety

All mandatory Personal Protective Equipment (PPE) shall be worn in addition to the relevant PPE if needed. If cleaning by brush, eye protectors must be worn. If using fluids, understand that some products are highly inflammable. Wear a respirator if cleaning with a pressurized spray system.

Don’ts

Lubrication Method

Over-lubrication can cause the lubricant to accumulate and attract dirt and debris, leading to wire rope wear.

Safety

Don’t discount the potential safety hazards of working on a moving rope.

Please don’t attempt to clean and lubricate the wire rope while it is suspending a load unless otherwise stated in the OEM’s instruction manual or other relevant documents.

Proper lubrication is essential for protecting the dynamic steel wire rope against corrosion and contaminants and for protection from wear and other potential damage. Select the right lubricants, following the most suitable application method, and lubricate at the optimum frequency.

A helpful starting point would be a review of the lubrication recommendations and any specific requirements specified by the wire rope manufacturer and OEM of the equipment.

Precision lubrication is vital for extending wire rope lifespan but is not the only parameter to address. Proper storage conditions, handling, precision installation, and regular inspection can help prolong the service life of the wire rope and reduce maintenance costs.

[1] DIN 15020: Lifting Appliances; Principles Relating to Rope Drives; Calculation and Construction.

[2] ISO 4346: Steel wire ropes for general purposes — Lubricants — Basic requirements.

[3] ISO 4309: Cranes — Wire ropes — Care and maintenance, inspection, and discard.

[4] Wire Ropes; Tension, Endurance, Reliability; Second Edition; Klaus Feyrer. pp 31 to 33.

[5] Lubrication and Reliability Handbook; M.J. NEALE pp A10.1 from to A10.3.

[6] Handbook of Lubrication and Tribology; Volume I: Application & Maintenance; Second Edition; George E. Totten. pp from 15-1 to 15-6.

Like other condition monitoring techniques, oil analysis is vital in monitoring equipment health and maintaining performance. It aims to detect underlying root causes of failure and early-stage potential failures before they cause significant damage.

Oil sampling is an essential process in oil analysis. It consists of drawing a small amount of oil from the equipment, analyzing it to assess its condition, and looking for early signs of wear and contamination.

Why Draw Oil Samples?

Oil analysis helps us monitor the oil condition and the current operating state of the equipment in which the oil is used. Accordingly, it helps optimize costs and productivity and helps ensure safe working conditions.

There are several desirable outcomes of a successful oil analysis program, including:

Lubricant Condition Monitoring

Over time, oil can break down, become contaminated, and its properties can degrade. Lubricant Condition Monitoring deals with the assessment of the chemical, physical and performance properties of the oil.

Testing and verifying these properties can assess the oil’s remaining useful life and determine when it has become degraded and not serviceable anymore.

Checking the condition of the oil reveals meaningful information. It will tell us, for example, if the oil’s viscosity changed due to contamination, oxidation, thermal degradation, or other chemical reactions.

Additionally, it informs about depleted or impaired additives and the damage of base oil by oxidation, hydrolysis, or thermal degradation.

Equipment Health Monitoring

Maintenance technicians can identify needed corrective actions early on by analyzing the oil for developing evidence of abnormal wear, oil properties degradation, and contamination, such as filter change, oil filtration, oil dehydration, or even oil replacement.

This helps prevent significant damage and costly repairs or replacements. Thus oil sampling can help improve equipment performance and extend the overall usable life of lubricant and equipment.

Oil analysis helps reduce sudden in-service failures and is essential even before equipment commissioning.

Oil analysis can confirm if new equipment has a manufacturing defect and has been properly commissioned.

Additionally, oil analysis can help establish if a machine has been adequately repaired or rebuilt. It can also help identify lubricant-related sabotage activities.

Lubricant Pollution Measurement

Given that the lubricant is a carrier of information about machine and lubricant health, it is also an effective carrier of information about the pollution state of the machine.

Moreover, oil analysis can reveal the presence of undesirable contaminants, either liquid or solid (cross-contamination with other fluids or lubricants, fuel, water, process fluid, coolant, soot, dirt, rust, etc.). Proper corrective actions to address external contaminants identified in analysis ensure that goal-driven contamination targets are maintained.

Cost Optimization

Many potential problems can be identified thanks to oil analysis before they become severe enough to cause equipment failure or downtime. Equipment is maintained in good condition, unplanned downtime is minimized, and productivity is steady.

By assessing the combustion quality and identifying faults that lead to engine inefficiency and excessive fuel consumption, like a leaky fuel injector, oil analysis can help machine owners lower fuel consumption.

Additionally, oil analysis can help improve the quality of equipment and lubrication maintenance decisions. Drain intervals can be extended by establishing condition-based oil changes and maintenance actions, leading to reduced oil consumption. Unnecessary maintenance, such as time-dependent component changes (oil, filter, and separator replacements), can be reduced.

Safe Working Conditions

Oil analysis is an excellent tool for maintaining and improving safe working conditions. Regular oil analysis helps ensure that equipment functions properly and safely, reducing the risk of accidents and injuries to operators and workers.

Contaminated or degraded oil can lead to increased friction, wear, and heat, which can cause machinery malfunction or even a safety hazard to workers and operators.

Regarding environmental compliance, if you use lubricants, you must dispose of them when changed. By reducing oil changes, you reduce your environmental impact.

What Equipment Should Be Sampled?

When selecting equipment to be monitored by oil analysis, consider the following criteria:

Equipment Criticality

Overall Lubricant Criticality (OLC) is one of many existing methods and approaches to determine equipment criticality. What is specific with OLC is that it assesses the criticality of equipment in the context of lubrication.

It defines the overall importance of lubricant health influenced by both the probability and consequences of lubricant and machine failure. OLC involves the following factors:

• Machine Criticality Factor (MCF): This factor is associated with the consequences of machine failure, combining mission criticality and repair costs.
• Failure Occurrence Factor (FOF): Corresponds to the probability of failure. This probability is highly influenced by maintenance and lubrication practices.
• Lubricant Criticality Factor (LCF): Defines the economic consequences of lubricant failure. The cost of the lubricant affects the LCF, the cost of the downtime to change the lubricant, the flushing cost, the system disturbance cost, etc.
• Degradation Occurrence Factor (DOF): Defines the probability of lubricant failure. Influencing sub-factors include lubricant robustness, operating temperature, contaminants and other exposures, lubricant makeup rate, etc.

How Often Should You Sample Oil?

Once the equipment is selected to be monitored by oil analysis, it is time to define how often it should be sampled. This is not an easy task as oil sampling frequency can be a complex process that requires careful consideration of several factors, such as Equipment Criticality, Equipment Type, Oil Type, Cleanliness Target Tightness, Historical Machine Failures, Failure Modes, Fluid Environment Severity, and Operating Conditions.

Sampling less frequently can risk missing a machine or lubricant failure. Sampling more frequently can waste time and money. For example, machines that operate in harsh conditions or are subject to high loads may require more frequent sampling.

Machines that use synthetic oils may require less frequent sampling as they are more resistant to oxidation and contamination. The more we know about the equipment, the easier it is to determine the optimum sampling frequency.

On the other hand, many general advisory recommendations can be found. Experts in the field can also be consulted to determine the appropriate sampling frequency based on their experience with similar equipment. Additionally, OEM and oil suppliers can provide valuable advice.

The frequency of oil changes is determined so that the oil remains serviceable and can fulfill its technical functions inside the equipment between two complete oil changes. Be sure to take a sample well before the end of this period to detect early signs of wear, oil degradation, and contamination.

When implementing an oil analysis program with no OEM recommendations for oil sampling frequency, consider sampling it at 2/3 of the oil change frequency (see figure below). The frequency can be adjusted after enough data has been collected.

Who Should Draw Oil Samples?

The International Council for Machinery Lubrication (ICML) has detailed in ICML 55.1 the required skills and qualifications for all personnel involved in lubrication management.

For lubrication technicians designated to execute routine tasks as defined in work procedures and job descriptions (task-based training), the body of knowledge set forth is Machinery Lubrication Technician (MLT-I) or equivalent. Oil samples should be drawn by qualified technicians who:

1. Understand what a representative sample is.
2. Are familiar with the equipment being sampled.
3. Have mastered oil sampling procedures.

In conclusion, every oil sampling strategy cannot apply to all equipment and applications. When an oil sampling program is well designed and implemented, the equipment life can be extended, the risk of costly breakdowns can be reduced, and safe working conditions are ensured.

However, it is crucial to consider adjusting the oil sampling frequency over time as a lubricant, operating conditions, and other factors change to ensure that it is still convenient for the context where it was initially established.

Additionally, a cost-benefit analysis should be considered. More frequent sampling may provide more data and earlier identification of impending failures, but on the other hand, it involves more costs. Finding the balance between adequate data and cost-effectiveness is crucial.

Lubricants are the lifeblood of machines. Like a blood test, lubricant analysis can provide early warnings of impending failures, far in advance, before it is too late to take timely action. But not all oil samples can give such alerts completely!

Only representative samples lead to correct conclusions regarding machine performance and lubricant health. Drawing a representative sample is the oil analysis program’s cornerstone and a fundamental step to achieving its related goals. 

Getting a representative oil sample is about more than just the right sampling location, the right sampling method, and the right sampling tools. It is about the right identification of the sample as well!

Many laboratories and consultancy firms specializing in lubrication and reliability have published articles about sampling locations and methods. But in this article, I would like to focus on how the proper labeling of an oil sample is as important as choosing the best sampling location and following the most accurate sampling methods. 

Equipment Identification 

Equipment identification includes providing the equipment name, description of component sampled (e.g., hydraulic tank and engine crankcase), equipment OEM, equipment model, equipment serial number, fleet number, etc.

This identification should be precisely the same for each sample. If not, the equipment could be registered with the oil lab as the wrong equipment, and the trending history will be lost. Using a unique ID provided by the laboratory for each piece of equipment is better. 

Additional identification data to be provided: Sump capacity and cooling mode (air, oil, or glycol-based liquid ) are also helpful when submitted with the oil sample.

Oil in Use

For the oil in use, make sure to identify its brand, its name, its type, and its viscosity grade. Since oil manufacturers produce hundreds of products, providing only the oil brand, such as Shell or Total, or providing only ISO VG 320 or SAE 5W30, with no additional information, is not enough. 

Oil analysis is about assessing oil properties, wear, and contamination. The lab must know the oil that is in use so that the analysis can be performed correctly.

Molybdenum, for instance, is a metallic additive used by some lubricant manufacturers, whereas it is considered wear or contaminant for other lubricants. In this case, the diagnostician could make a wrong conclusion simply because he is unaware that Molybdenum is within the oil formulation.

Component Age

Component age can be provided as the number of operating hours, kilometers, or miles on the equipment since commissioning. Providing this information will help the oil analyst benchmark with similar equipment operating in a similar environment. 

Oil Age

Oil age reflects the oil usage between the last complete oil change and the moment of sampling. It is typically reported in hours, kilometers, or miles. This information is essential to accurately identify a divergence from normal wear patterns by normalizing elemental data to “Rate of Wear” calculated by the formula below. 

Hours of operation could be kilometers, hours, or days. Recording the sampling date is complementary information, especially if oil sampling is triggered on a calendar basis.

Let’s look at the elemental analysis values extracted from a gearbox oil analysis report. The first reading of iron content in sample 04 and sample 05 will tell us that sample 04 wear is higher than sample 05. But the oil in sample 04 was in service for 73 more hours. The oil age is helpful in correctly assessing elemental analysis data.

Top-up Amount

The top-up amount refers to the volume of oil added between the last complete oil change and the moment of sampling. Topping-up oil helps normalize wear, contaminants, and additives. Adding fresh oil to your equipment between oil samples affects oil analysis data because of dilution. 

Additional Information 

The more information provided to the oil analyst, the more accurate and relevant the findings will be. These include:

• Lubricant abnormalities such as bottom sediment and sludge, foam, and varnish. 
• Work performed on the sampled equipment like an overhaul.
• Operating conditions like speeds, loads, service duty, ambient temperature, operating temperatures, and potential exposure to contamination such as dust or salt water.

Completing the standard oil sample form is often a source of errors, either needing missing information or poor handwriting. In this era of digitalization and to reduce the risk of inadequate sample labeling, many laboratories provide web platforms and mobile applications, which are not only for oil samples pre-registration but also for analysis data management. 

In such cases, the laboratory provides sampling bottles already labeled with barcodes. Equipment should already be registered, and there is no need to enter information like equipment ID or machine serial number – only changing information like running hours and top-up amounts.

The key takeaway is that oil analysis results are interpreted based on the sample submitted and the supporting information accompanying it. The more accurate information you share with the lab, the more precise the diagnosis.

So, labeling the oil sample accurately and thoroughly, either by handwriting or registering online, is urged to guarantee an accurate oil analysis interpretation.