Intermediate storage and handling of lubricants
Storing and handling lubricants is a lot like running a kitchen. Cleanliness, inventory management and safety precautions ensure efficient operations and save time and money.
- Maintaining lubricant cleanliness and integrity pays off in cost savings and operational safety and efficiency.
- Lubricant containers must be stored with easy and safe access and transport in mind.
- Site inspections, thorough record keeping and stock rotation help ensure good practices are followed.
How effectively lubricants do their job, and for how long, depends on what they encounter between the supplier’s delivery truck and their destination in bearings, gears and other mechanical components. “We need to take the lubricant delivered to our facilities with extreme care and precision to make sure the integrity of the product, the labels and other factors stay intact and that the lubricant is as clean — or even cleaner, in many cases — than what is delivered from our suppliers,” said Society of Tribologists and Lubrication Engineers (STLE) member Manuel A. Garcia, senior technical services advisor for Petro-Canada Lubricants LLC, in a recent webinar presented by STLE Education. This article is based on an STLE Education Webinar presented Oct. 14, 2020, by Garcia.
Good storage and handling practices reduce oil usage by minimizing leaks, spills and drips from improperly closed containers and during transfer from containers to machine reservoirs. Contamination is reduced because lubricants are not exposed to dust, metal particles, fumes and moisture. Tracked and rotated lubricant inventories are less likely to degrade by being stored past their “use by” dates. Environmental contamination is reduced if residual oils and greases are cleaned from containers before they are disposed of. Proper labels, maintained in a legible condition, and a color-coding system reduce the likelihood that incompatible lubricants will be mixed in a machine.
The results are measurable in economic and operational terms. “It costs 10 times as much to clean dirty oil as it costs to keep it clean in the first place,” Garcia said. “The single greatest opportunity for increasing component life and lowering operating costs is to effectively manage fluid cleanliness. It does not matter how great our predictive and preventive maintenance practices are in any plant if we can’t assure the correct clean oil at the right time, in the right amount at the machines.”
Making sure the right lubricant goes into the right part of a system and avoiding unintentional mixing of lubricants pays off in reduced repair costs. Critical systems are less likely to fail if they are protected by lubricants with the right formulation for their operating temperatures, loads and speeds. The right lubricant formulation, uncontaminated by other lubricants, particulates and moisture, can prevent catastrophic failures of expensive systems, eliminate critical backstop repairs, reduce the overall budget for repair parts and reduce labor costs and downtime.
Oil room design
Oil storage rooms should be customized to suit the application (steel mill, food processing plant, etc.) as well as the size of the plant they serve. The first rule of setting up an oil storage room is “location, location, location,” Garcia said. Plant workers must be able to get to the products effectively and efficiently, and the oil products should be close to the equipment where they are used. The overall layout, as well as storage containers and cabinets, should be planned with fire and worker safety in mind.
Lubricant containers should be stored in a way that makes it easy to rotate the stock. The general rule is “first in, first out” (FIFO) to keep older containers from being stranded past their expiration dates in the back of the storage room. Lubricant suppliers can provide date information corresponding to batch codes, and these codes can show which slow-moving products are nearing their expiration date.
One simple oil room layout uses three separate areas to reduce the risk of airborne contamination (see Figure 1). Unopened drums are received and stored in the outermost room, which also can be used for filter cart storage.
Between the receiving room and the office is a “clean room,” a controlled-access space where lubricants are transferred from drums into smaller containers for transport to various parts of the plant. Because sealed containers are opened here, this room should have filtered air and temperature control. Sealed floors and walls make it easier to clean up spills. Lubricants should be segregated by product family, with a color-coding system to prevent cross-contamination or using the wrong lubricant.
Figure 3: Satellite storage facilities. Courtesy: STLE[/caption]
Shelves, cabinets, lockers and tank stands keep lubricants clean and organized, and they can reduce spills and worker injuries by making it easier to dispense lubricants into smaller containers for transport to the point of usage (see Figure 4). Storage cabinets of various sizes must have locks or other access control and fire safety ratings appropriate for the type of lubricants or equipment stored in them.
Storage tanks should be clearly labeled with the identity, vendor information, delivery date and use by date of the product inside. Color-coded labels, tags or container lids provide a quick check to avoid mix ups. Printed tags are easier to read than handwritten tags, which also tend to wear off easily.
The oil coming out of clean room tanks should be at least as clean as — if not cleaner than — the way it was received from the vendor. Oil should be filtered when it is transferred from the vendor’s containers into storage containers in the clean room and filtered again when it is transferred into smaller containers for transport into the plant. Desiccant breathers, which might need to be upgraded from the ones supplied by the original equipment manufacturer (OEM), help keep moisture and particulates as small as 0.5 micron out of a tank’s headspace. Portable filter carts are another effective tool for extending fluid life and reducing the amount of fluids purchased.
Record keeping and controls
“Oil rooms and procedures must be designed to facilitate record keeping,” said Garcia. “Fluid deliveries and usage must be accurately metered and recorded. Record keeping not only saves costs by keeping track of the amounts and ages of your lubricants inventory, but it also helps to locate equipment leaks by comparing monthly consumption and comparing it to expected amounts.”
Lubricant record keeping can be as simple as recording orders and deliveries on a clipboard or a computer spreadsheet, along with dates when plant workers take lubricants out of the storage room, how much and where it’s going. Periodically examining these records helps track which machines and departments use more oil than others and which applications are the most critical. Tracking lubricant use and storing containers in an organized fashion also ensures that there aren’t multiple partially used containers of fluid sitting around the storage room.
Table 3: Life extension table (LET) shows extensions of service life for specific reductions in particulate levels. Courtesy: Noria Corp.[/caption]
The effects of fluid leaks
If your records indicate a particular piece of machinery is going through oil much faster than it should, chances are some components are leaking. “In North America alone, an estimated 100 million gallons of fluid could be saved annually by eliminating external leakage from hydraulic machinery and other lubricated equipment,” Garcia said.
Leaks can increase fluid consumption, cause machinery to operate inefficiently, cause environmental damage and pose safety and accident liabilities (see Table 1). Leaks also contribute to premature machinery component failure and can result in poor manufactured product quality (e.g., discolored fabrics or off-flavor food). They increase capital costs and fluid disposal costs, and they contribute to ancillary costs like floor dry and pig products to sop up leaks.
The hydraulic fluid index (HFI) is a convenient way to monitor monthly fluid consumption and schedule leak inspections. The HFI is the ratio of fluid consumption to reservoir capacity, and it can be monitored on the facility, department or machine scale. “The average industrial plant,” Garcia said, “has an annualized HFI of about 3:1, but plants that are especially diligent about identifying and repairing leaks can achieve an HFI of 1:1 or less.”
Going through an entire plant and finding all the leaks is a daunting task. Garcia said, “Significant savings can be achieved by applying the Pareto principle: Find and repair the 20% of your systems that account for 80% of your leakage. If your HFI numbers decrease over time, that means you’re operating your facility more efficiently.”
Plant workers should be trained to observe best practice guidelines for keeping lubricants cool, clean, dry and free of dust. Dust acts as an insulator that traps heat inside machinery. It’s essential to wipe dust from gearbox housings and other components where it is prone to collect. Dip sticks and funnels should be wiped with a clean rag to remove dust and residual oil before they are inserted into a reservoir. Tank breather filters should be inspected, maintained and replaced regularly, and they should be wiped down with a clean rag to remove dust. All oil dispensing containers and equipment (funnels, grease guns, oil cans, etc.) should be kept clean and dry and stored in clean conditions.
Before injecting grease into a bearing or other part, all grease fittings must be wiped off with a clean rag. This not only ensures that dust doesn’t enter the component, but it also helps prevent oil from contaminating the grease. “No level of oil contamination (even down to the ppm level) is allowable in any oil or grease system,” Garcia said. Critical manufacturing equipment should have regular oil analysis to spot potential problems before they get out of hand.
Clean, dry oil extends equipment life
Clean rooms, locked cabinets and color-coded systems might sound like they belong more in a hospital than in a manufacturing plant but keeping lubricants clean and segregated can save significant time and money on equipment replacement and repair.
ISO cleanliness codes quantify the amounts of various sizes of particles in a lubricant. Three numbers indicate 4-micron, 6-micron and 14-micron particle counts per milliliter of fluid. For example, an ISO cleanliness code of 18/16/13 indicates 2,136 particles counted greater than 4-microns, 463 particles counted greater than 6-microns and 63 particles greater than 14-microns per milliliter of fluid. Comparing ISO codes for current lubricant conditions with recommended levels provides an idea of how running cleaner fluids can extend service life for various types of systems (see Table 2).
In table 3, initial ISO cleanliness levels are shown in the tan boxes in the left column. Improving ISO cleanliness values in the red boxes in the top row extends service life by the factors indicated in the white boxes where the row and column intersect. The legend at the bottom left indicates the types of parts for each number in the white boxes. For example, going from 22/20/17 to 17/15/12 extends the service life of hydraulics and diesel engines by a factor of 4. Table 4 shows similar information for the benefits of reducing moisture contamination. For example, reducing the moisture level in a mineral-based oil from 2,500 ppm to 156 ppm extends service life by a factor of 5.Case study: Investigating a contamination situation
Proper storage and handling of lubricating oils and greases requires managing them “cradle to grave.” Garcia said, “A service call can serve as an opportunity for best-practices training. A technical representative on a walking tour of the plant floor and storage facilities with the end users, asking questions along the way, can identify the causes of most issues related to contamination control.”
He referred to an example of a customer who routinely found contaminant deposits at the bottom of his turbine generator oil barrels. These contaminants were not apparent when the containers were new, and the manufacturer had not reported problems, so a technical representative and a sales representative from the supplier scheduled a site visit to assess the problem firsthand.
The representatives found oil and grease containers stored in a dark, dirty, damp basement room (see Figure 5). New oil drums sat next to used oil drums, and various lubricants were stored in open, unmarked containers. Kerosene and gasoline containers shared the space with oily rags and open oil and grease containers. Funnels and pumps were covered in dust, dirt and rust. Beads of water condensation and leaking oil covered container lids. A board, used as a worktable, had been placed on top of several new oil drums, blocking off the breathers.
When plant operators needed to top off an oil reservoir, they inserted a drum pump into a large bulk drum. They transferred the needed amount into a metal bucket, which could have been releasing rust or dissolved metals into the oil. Between refills, the pump was stored in the bucket, which was never cleaned. They typically used one or two gallons a week, so by the time the drum was empty, the pump had been inserted into the drum more than 20 times. Each time, the pump transferred some of the dirt, dust and oil residue from the bucket into the drum, and the contaminants built up in the drum over time. The portable filter cart was covered in dust, and the heavy dirt buildup on the hose and wand assembly was transferred into the generator’s oil reservoir every time the filter cart was used.
The supplier’s representatives reported their findings to the customer’s maintenance management team. They also provided hands-on training to the maintenance team on duty, showing them the proper procedures for keeping contaminants out of the oil barrels. They emphasized that following these procedures in the future will help the customer keep the oil in the turbine generator contaminant-free.
Doing it right
Garcia pointed out the importance of plant operators and managers working together with mechanics and maintenance personnel to prevent and remedy problems. Oil analysis from samples taken regularly from the same points using recommended procedures also can yield valuable information that can be used to identify and fix problems. Color coding and tagging equipment, good storage and handling techniques, desiccant breathers and portable filter carts, used consistently and correctly, can prevent problems from happening in the first place. The goal is a clean and organized storage area.
This article first appeared in Tribology & Lubrication Technology (TLT), the monthly magazine of the Society of Tribologists and Lubrication Engineers (STLE), an international not-for-profit professional society headquartered in Park Ridge, Ill., www.stle.org.