Lubricants play a vital role in the reliability of any equipment. It is not only the oil quality but, most importantly, the oil storage and handling practices that enhance the reliability and life cycle cost of machines.
By Bhaskarudu Peddakotla
All fleet owners follow the equipment manufacturer guidelines in usage of appropriate grade of oils and when it comes to quality, some customers will go with the oil brand and some customers prefer proof of testing from oil labs. But few understand the importance of oil storage and handling.
Oil Storage and Handling
This job of ensuring proper storage and handling of lubricants is entirely in the hands of the fleet owner. Protecting lubricants is protecting the machine, but unfortunately, people at many sites do not pay serious attention to lubrication storage and handling practices as they are not aware of the repercussions and the problems that can arise with improper storage and handling. Lapses may be in providing improper covered storage facility, exposing barrels or containers to the open atmosphere; missing or loose fixing of caps; mixing of different oil grades; inadequate oil handling tools; using dirty cans to carry oils, etc. All these lapses expose the oils to dust (silica) or moisture (water).
Dust in lubricants
After oxygen, silicon is the most abundant element available on earth and more than 90% of earth’s crust is composed of silicate minerals; quite literally, there is no job site without silicon.
Silicon when it joins with oxygen becomes silica - the most abrasive material; even more abrasive than any ferrous, copper or aluminium parts used in the power train components of a machine. Construction or mining site operations are prone to fine dust (fine silica particles). Clearances between moving parts of the engine and other power train components are very thin in order to balance both sealing and lubrication film. These dust particles when mixed with the lubricant, pass between the piston, rings and cylinder and eventually become suspended particles and start “scratching” the surface. The next action will be induction of dust particles between two metallic surfaces, affecting uniform load distribution and leading to concentrated load on particles, with tremendous increase in pressure at the point of contact. All these lead to rapid wear and premature failure of engine and other power train components, and wherever the contaminated oil passes. Fine particles that are equal in size to the oil film are more harmful as they can easily pass along with the oil and act as a scratching medium.
Effect of dust in lubricants
Dust that enters the oil cannot be easily taken out and the lubrication activity turns into metal scratching, which leads to rapid wear of all parts where the oil passes through, such as the engine piston rings, liners, valve train, bearings, hydraulics pumps, motors, cylinder seals, barrels, transmission components, final drive parts, etc.
Most of the causes for premature failure of engine and other power components are attributed to dust entry. So, if one takes proper care in protecting the lubricants from dust, the reliability of the machines can be improved a lot and their life cycle cost can be minimized significantly.
Water in lubricants
Water can exist in oil in three states: dissolved, emulsion, and free. The dissolved phase is the dispersed state of water molecules throughout the oil, but invisible. This can be found in fresh oil to the extent of 500 ppm (0.05%). When the water content exceeds beyond the dissolved state, it is considered as emulsion state, where microscopic water droplets are found in suspended form in the oil. This is like a foggy weather, wherein (in lubricants) fog is referred to as haze, which means a kind of cloudy appearance of oil. Further water contamination is the free state where water can be seen in a ‘separation’ form from the oil. As most of the lubricants’ specific gravity is less than 1.0, water formation can be seen below the oil.
Effect of water contamination
The most harmful water contamination stages are free and emulsion phases. For example, in crankshaft journal bearings, the incompressibility of water relative to oil can result in a loss of the hydrodynamic oil film, which, in turn, leads to excessive wear. It is so serious that one percent water in oil can reduce the life expectancy of a journal bearing by as much as 90 percent!
For roller bearings, the damage will be worse because the water not only destroys the oil film strength, but also causes instantaneous flash-vaporization under the extreme temperatures and pressures in the load zone of rollers, which leads to erosive wear.
Protecting lubricants from dust and water
- Depending upon the size of the fleet, proper oil storage room has to be maintained by providing the required facilities like pneumatic oil dispensing pumps with flow meters and adequate hose length, oil barrel covers, storage pallets, separate cans for each grade of oil etc.
- Moisture trapping filters to be provided in compressed air line and condensed water to be drained at regular intervals from air reservoir.
- Manual oil pumps are to be avoided however small the fleet size may be. Under unavoidable circumstances, for a single or two machines, small size oil cans to be procured.
- Oil top-up for tyre mounted machines has to be done directly through hose provided to oil pump.
- No drained or used oil to be stocked in the same room where fresh oil is stocked.
- Oils and grease have a shelf life and there is possibility of depletion of additives’ strength when oil is stored beyond its shelf life. So, oils are to be consumed on first come first serve basis. Whenever new stock arrives, it is to be stocked behind and the old stock kept in front.
- Clear signboards with ‘oil grades’ and ‘which compartment to be used’ are to be displayed in local language against each barrel.
- Lifting and carrying trollies are to be provided and fire extinguishers to be kept in storage room.
- Implement 5S workplace organization practices: Sort, Set in Order, Shine, Standardise and Sustain.
- Above all, educating the maintenance team on the importance of lubrication storage and handling is very important because unless the frontline technicians understand and feel ownership, execution will not be effective.
By maintaining good oil storage and handling practices, one can also reduce oil change intervals suitable to specific sites and thereby have additional savings. Cost incurred for maintaining contamination-free storage and handling facility is very little as compared to the benefits obtained through improved machine uptime and lifecycle cost of the machine.