Clean Machines: Cut Operating Costs with Contamination Control
Investing in a clean-fluids strategy can pay dividends in machine availability
By Russell A. Carter, Managing Editor
Component life, according to Simon Bishop, a product support specialist with Caterpillar Global Mining, is a function of basic design, proper application, and quality of maintenance and repair. A major factor within “quality of mainte- nance” is selection of the proper fluid(s) required by a component, such as fuel, oil, grease, coolant or hydraulic fluid— and implementing the correct proce- dures to ensure that these fluids aren’t contaminated before, during or after installation.
It’s estimated that equipment mainte- nance and repair expenses account for about one-third of overall haulage costs. Taking it one step further, Caterpillar reports that maintenance/repair costs involving transmissions, hydraulics, final drives/differentials and fuel injectors typ- ically total up to 70% of overall machine operating costs. And to top it off, some studies show an estimated 75% of com- ponent failures are the result of surface degradation caused by fluid contamina- tion. So, it’s simply good business to pay attention to the fluids that keep major components functioning as originally designed.
How, exactly, is fluid contamination defined? According to Bishop, it’s any- thing found in a fluid that doesn’t belong there. Contaminants generally fall within two basic areas: particulates (dirt, met- als and fibers), and other unwanted ingredients such as water, air—even heat. Although many of the latest oils, greases and coolants are, for the most part, high-tech products designed for use in high-tech equipment, the process of contamination often begins at a very low-tech level that can involve every- thing from whether and how well a vehi- cle is washed before it enters the shop, to what type of material the maintenance crew uses to soak up accidental oil spills. Contamination problems aren’t always apparent to the naked eye; even particulate contaminants that are con- sidered large are still less than one-fifth the thickness of a human hair, while small particles are about one-third the size of the big ones.
Fluid contamination control in all phases of off-road equipment operation is a concept that has rapidly gained trac- tion in recent years, due in no small part to new technologies, tighter regulations, basic business economics and other fac- tors that are forcing equipment owners and operators to consider the expensive consequences that can result from lax fluid storage and handling practices. As Caterpillar’s Bishop explained in a pres- entation at the 2010 Cat Global Mining Forum, inattention to contamination con- trol can be disastrous to an operation’s bottom line—and conversely, a well- planned and executed CC program can yield millions of dollars in reduced repair and replacement costs over a haulage fleet’s life cycle.
Citing a case history involving an African open-pit mine, he noted that after the operator implemented “world-class” fluid cleanliness practices for the mine’s fleet of Cat 785C haulers, component life-cycle increases ranging from more than 28% for truck engines to almost 62% for wheel group assemblies were achieved, wheel bearing life was extended to 20,000 hours, and by eliminating one rear powertrain replacement over the course of a 785C’s life cycle, the mine was able to save $90,000 per truck, equating to a $3-million savings across the fleet. In addition, the mine had to replace only 16 fuel injectors in a fleet comprising 24 machines with 20,000 hours—representing one injector replace- ment every 35,562 operating hours.
Among the many factors that com-
prise a well-planned defense strategy
against premature parts wear, injector
longevity has grown to be an area of
major concern in recent years as new
engine technology puts these precision
components under increased duress.
According to Pall Corp., a global supplier
of fluid filtration and separation prod-
ucts, there are three types of engine fuel
injection system failures attributed to the
presence of particulate contamination:
• Mechanical failures from component wear and blocking component movement;
• Electrical failures (typically as injector solenoid burnout) from silting around the poppet valve stem, restricting movement; and
• Performance failures from blocking of injector nozzles and altering injector spray patterns.
The Port Washington, New York-based company notes that as diesel fuel injec- tion technology has progressed, so has its sensitivity to contamination. With new technology such as Electronically Con- trolled Unit Injectors (EUIs), injector nozzle openings are 6–7 µm in diameter. These openings can become blocked or suffer erosion from particulate contami- nation as diesel fuel is passed through them at high pressures. Nozzle shape can be changed or spray patterns altered, adversely impacting engine performance in the form of reduced power output and poor fuel economy.
The High Pressure Common Rail (HPCR) fuel injection technology used in the latest off-road diesels offers improved power and fuel efficiency and lower exhaust emissions. To achieve these results, however, HPCR systems operate at pressures in excess of 2000 bar and have injector nozzle openings in the 2–3 µm diameter range. This requires diesel fuel 30 times cleaner than that which is acceptable for standard EUIs and more than 100 times cleaner than what is typ- ically dispensed at the pump. According to Pall, this level of cleanliness cannot be achieved with onboard filtration alone; supplementary bulk and point-of-fill fil- tration is required.
The risk of fuel system problems also increases with the use of ultra-low sulphur diesel fuels, which newer engines are required to use. While it has been reported the removal of sulphur has shown no detrimental effects in engine performance, the removal of other com- pounds in the refining process can lower the lubricity of fuel, resulting in potential injector system component wear, espe- cially with modern fuel technology such as MEUI, HEUI and HPCR systems, which are far more sensitive to inade- quate lubrication from low lubricity fuels.
As previously mentioned, studies have shown major component life-cycle costs (calculated by determining cost to rebuild a component divided by compo- nent life in hours) represent the lion’s share of total machine operating costs— and engine costs alone represent about 40% of that share, followed closely by final drive/differential, transmission/ torque converter and miscellaneous costs. Given the potential damage con- taminated fuel can cause in modern diesels, plus the sheer volume of fuel that large mines require for operation, one of the largest payoffs from a contam- ination control effort would likely origi- nate from a mine’s fuel handling and storage facilities. Proper bulk storage of fluids—sometimes a forgotten link in the chain of fluid cleanliness—can play a huge role in combating contaminants.
Size Systems Carefully
As Pall Corp. points out in its technical literature, funding for capital projects such as fuel system upgrades can some- times be difficult to justify. Even when an upgrade has proven to be a necessity or at least a viable proposition, cost is one of the main defining attributes a mine site looks at when making a purchasing decision. The size of a filtration system is one of the main contributors to this cost.
Diesel filtration systems are typically sized using a formula that takes into account the pump flow rate (or rate of delivery required), fuel viscosity, fuel den- sity, and system pressures. Once these factors are known, a system can be sized. However, according to Pall, in many cases fuel filtration solutions that are being presented to mine sites are drasti- cally undersized for their intended pur- poses. Why? Because these systems are often missing one key aspect in the sizing formula—the annual fuel quantity being used at the mine site and the levels of contamination that this fuel carries.
It’s not unusual for a mine to con- sume more than 200 million liters of diesel fuel per year, and some larger mines may use more than 400 million liters annually. When dealing with these huge volumes, it’s important to under- stand the amount of contamination that the filtration system is expected to remove. Pall’s experience indicates that for a mine site with annual diesel fuel consumption of 200 million liters a year, with a delivered fuel cleanliness level of ISO 21/19/16, the amount of contamina- tion removed by a filtration system each year can total as much as 1.6 tons. Additionally, with a water contamination level of 500 ppm, a coalescer system would be expected to remove some 100,000 liters of water each year.
Using this fuel volume as an example, it’s important to understand the actual capacity of the filter elements typically installed in mining bulk diesel systems. Pall says it is common at mine sites to see filter installations sized to handle 1,200 liters/min of diesel fuel; such a system may have dirt-holding capacities as low at 900 grams for the three ele- ments in the housing at the given flow rates. Taking into account the 1.6 t of annual contamination, this equates to an annual consumption of 1,388 elements.
That rate of filter consumption, and its attendant costs, might overshadow any benefits from the installation at all. Pall, which in addition to its filtra- tion/separation product line offers fluid analysis services and component cleanli- ness auditing, thus emphasizes that many factors including pump flow rates, viscosity, density, temperature and pres- sure must be considered in any formula used to size a bulk filtration system—a task best performed by an experienced vendor.
Going Under Analysis
The care and cleanliness of engine lubri- cating oil is another critical area that can yield significant benefits from contami- nation control measures coupled with an oil analysis program. Oil analysis services are available from many sources, and recent developments in this technology now allow thorough analysis at almost real-time rates.
WearCheck, a company that special- izes in oil analysis, emphasizes that the effectiveness of any oil analysis program is strongly affected by how well the main- tenance staff understands the program and by the quality of their input to the testing service. An important fact to bear in mind, according to the company, is that oil analysis should not be viewed as a replacement for normal maintenance techniques. It is a first-stage monitoring tool that identifies a problem; diagnostic tools are then required to physically con- firm the problem and isolate the defec- tive component. Oil analysis comple- ments diagnostic tools, it does not replace them. When the information from all testing sources is combined, the result is a powerful management tool for monitoring and controlling machine health.
Oil analysis works on the principle of
detecting progressive wear by establishing
a baseline of normal wear metal and con-
taminant levels and trending the results
from subsequent samples. WearCheck
recommends implementing a set of basic
policies that can maximize the effective-
ness of any oil analysis program.
• Ensure total commitment from top man- agement all the way down to the work- shop floor.
• Make members of the maintenance team aware that their efforts do make a difference to the longevity of the machines.
• Clearly define and communicate sam- pling policy and frequency.
• Appoint and train responsible people to take the samples and complete the sample submission forms accurately.
• Appoint a competent senior mechanic to carry out troubleshooting and ensure all physical diagnostic tools are available.
• Train a clerk to keep accurate records of oil analysis and physical tests car- ried out on components at service intervals and during troubleshooting.
• Ensure feedback is returned so that oil analysis records can be updated and the information is available to the diagnosticians.
Counting the Costs
It’s been estimated the actual costs of basic contamination control and overall systems cleanliness in an operation often amount to less than 3% of poten- tial total costs incurred due to fluid contamination—not bad for an invest- ment that has the potential capability to reduce an operation’s maintenance budget, increase fleet mechanical availability by significant single- or even double-digit percentage points, and even improve employee morale and accountability.
Take the First Step in Contamination Control: Delete Dirt and Debris
A contamination control program doesn’t have to be high-tech to be effective—but it does have to include all areas of an oper- ation that may contribute to fluid contamination problems. Here are a few basic guidelines that can help achieve a higher level of cleanliness:
The approach area to a service bay should be paved with gravel or concrete and kept free of dirt and debris. Machines and components should be washed with high-volume, high- pressure hot water and soap before entering the shop. Inside the shop, maintain good housekeeping practices by:
Contamination control starts with good basic housekeeping: shop-approach
aprons should be paved and kept free of dirt and debris. Interior floor surfaces
should be sealed and accidental fluid spills should be cleaned up with absorbent
pads or with a wet/dry vacuum. Avoid using granular absorbent materials that can
create airborne dust.
• Cleaning floors daily. Consider sealing floor surfaces.
• Keeping tools clean and organized.
• Keeping work benches clean and organized.
• Storing parts off the floor.
Use a vacuum or absorbent pads to clean up accidental spills, and finish the cleanup with a powered floor scrubber, or mop with degreaser. Avoid using granular absorbent materials that can produce dust.
All hose and tube ends should be plugged or capped. Hoses and tubes removed during a repair should be cleaned internal- ly before being reinstalled. Keep parts/components packaged until ready to install. Protect in-process parts when not being worked on.
Consider using an oil-service preventive maintenance cart
Filter all new fluids upon arrival and during transfer. Seal fluid reservoirs and bulk tanks. Install high-quality des- iccant and particulate filters on tanks. During refueling proce- dures, clean fueling ports and nozzles before fueling and cover them after fueling. Drain sediment and water from machine tanks at PM intervals, as part of PM checklist.
On-site Fluid Analysis in Minutes, Not Days
It didn’t take a six-year federal study to show that miners want fluid analysis equip- ment on-site for speedy but comprehensive results as part of their equipments’ preven- tive maintenance programs. But that’s what a 2004 U.S. Department of Energy study concluded, and what an increasing number of players in the mining industry, including service provider Megatrol Inc. and equipment provider P&H Mining Equipment, are moving to implement.
“To stay maximally productive, mines need real-time information they can act on as part of their daily planning instead of a periodic checkup,” said Tom Barnes, product support manager, P&H Mining Equipment, “Equipment is bigger and more complex; mines are more remote; and technical help is harder to get, espe- cially in emerging markets.”
Claimed to be as easy to use as an ATM, more and more mine operations are using fluid diagnostic
equipment at their sites such as these from On-Site Analysis Inc. These on-site analyzers provide
comprehensive results in 10 minutes or less showing metal wear, contamination and other factors.
Fluid analysis is vital to machine health, but collecting and sending hun- dreds of lubricant samples each month to an off-site laboratory is costly at more than $20 per sample. That cost is multi- plied when mine managers have to wait for results, anywhere from days to weeks.
Real-time on-site analysis is now elim- inating the wait and reducing the cost. In 10 minutes or less operators can have comprehensive analysis showing metal wear and contamination before equipment loss and downtime become catastrophic, allowing mine managers to repair their equipment faster and get it back in serv- ice more cost effectively than ever.
Jon Rose, who has 40 years of experi- ence in the mining industry as owner of Megatrol Inc., a provider of proactive solutions for efficient mining equipment management and maintenance, said “An extra hour of operation can lead to very expensive downtime and that is a prime reason for on-site oil analysis.”
For real-time analysis and repeatabili- ty of data that can help maximize mining equipment production uptime, Megatrol turned to On-Site Analysis Inc. (OSA), a global leader of used-fluids diagnostic analysis technologies. OSA was formed to address the market need for faster, com- prehensive, laboratory quality testing and consequently developed the MicroLab on-site analyzer. Essentially a “lab in a box,” the on-site analyzer was developed to produce lab quality results in a small- er package and with an easy to use touch screen interface.
The analyzer can identify the pres- ence of 20 metals, measure physical properties such as glycol, TBN, soot (diesel engines only), fuel dilution, water, nitration, and oxidation, and also meas- ure viscosity. It has an integrated particle counter and provides comparisons against expected equipment wear rate curves similar to off-site labs, unlike hand-held analyzers that are limited to single tests like viscosity.
After analysis is complete, the equip- ment delivers a diagnostic report that includes suggested preventive steps. The data can be downloaded to a password-pro- tected Web site for review from anywhere in the world. Results also are e-mailed as an alert if an abnormal finding is discovered.
Megatrol is successfully using two OSA labs at a mine in Gillette, Wyoming, USA, testing 600 to 800 fluid samples monthly from a fleet of several hundred vehicles including trucks, dozers, scrap- ers, and support equipment. According to Rose, such fast test results from analysis can save an engine, transmission or a major bearing on key mine equipment.
“With timely on-site analysis and repair, a high-volume mine site could save thousands by avoiding unscheduled repairs and downtime,” said Rose. “By replacing a $5 hose in time, for instance, you could save a $120,000 engine or $70,000 transmission.”
Every minute of downtime is scruti- nized and any unscheduled downtime must be minimized, particularly on key equipment that can adversely affect pro- duction if that equipment breaks down, said Barnes.
P&H has added on-site fluid analysis to its Prevail Remote Health Monitoring Program, which expedites equipment diagnosis, maintenance, and repair through its MinePro Services network, and is starting to roll it out globally. The PRHM program allows managers and technicians to monitor all key equipment vitals online.
“Working with OSA, we’ve added on- site oil and hydraulic fluid analysis, plus an ability to track historic component wear trends with flexible online reporting to our ability to monitor vitals like tem- perature and equipment fault logs,” said Barnes. “This gives mine managers and technicians near real-time ability to ana- lyze, diagnose, predict, and respond to needed repair from a one-stop, secure website interface, or to receive critical email alerts. It also allows mine opera- tions to benchmark and develop trends which lead to optimized performance and best practices.”
According to Barnes, the availability of more immediate results allows operators to streamline preventive maintenance pro- grams and optimize routine maintenance tasks and oil change intervals. The improvement to machine availability and utilization alone can significantly improve the operation’s bottom line and has the additional benefit of reducing disposal costs and environmental impact.
As a result, “mines could achieve ROI in less than one year with the Prevail Remote Health Monitoring Program, including on-site fluid analysis,” said Barnes.
There’s an App for That…
Oil Conditioning, on the Spot
Fighting Fluid Contamination in Flood-Damaged Equipment
Widespread recent flooding in Queensland and other Southern Hemisphere regions has left many communities devastated and caused serious disruptions to industrial activ- ities such as mining.
In Australia, for example, flooding has affected the Queensland coal industry, not only causing producers to lose an estimated billion dollars in lost production, but also cost- ing them many hundreds of millions to repair machinery and infrastructure inundated by water.
Dingo Maintenance Systems, a supplier of mine-mainte- nance software solutions based on CBM and oil analysis prin- ciples, recently issued a technical bulletin outlining the types of damage to look for and the maintenance response needed to cope with water-damaged equipment.
According to the Dingo bulletin:
• The effects of water contamination can be wide-ranging,
If the vapor pressure of water is reached in the low- pressure regions of a machine, such as the suction line of a pump or the pre-load region of a journal bearing, the vapor bubbles expand. Should the vapor bubbles be sub- sequently exposed to sudden high pressure, such as in a pump or the load zone of a journal bearing, the water vapor bubbles quickly implode and simultaneously con- dense back to the liquid phase. The water droplet im- pacts a small area of the machines surface with signifi- cant force in the form of a needle-like micro-jet, which causes localized surface fatigue and erosion.
Water contamination also increases oil’s ability to en-
train air, thus increasing gaseous cavitation.