Industrial Lubrication Fundamentals: Storage & Handling
EP Editorial Staff | June 18, 2014
The journey from refinery to point-of-use can kill a lubricant.
By Ken Bannister, Contributing Editor
Many end-users believe a lubricant is purchased in an uncontaminated state and delivered in the correct formulation, as ordered, to begin its working life as soon as it’s dispensed into a machine reservoir or bearing point. This is not always the case.
From refinery to supplier
Lubricants start life as crude oil in a refinery where the process to separate their many components begins by boiling the crude at a temperature of 1100 F. The resulting vapor is allowed to enter the bottom of a cylindrical tower called a fractional distillation column that’s filled with trays at specific heights. As the vapor rises, the column temperature becomes cooler, causing elements within the vapor to condense into a liquid state when their boiling points match the column temperature. Lubricating base oils begin life fairly low in the column—at a temperature around 570 F—where they are collected and sent to a manufacturer’s lubricant-blending facility.
At the blending facility, additives are introduced into the base oil to make a finished oil product that is then quality-tested for purity and composition and stored in tanks for shipment to a packaging facility or regional/local bulk-lubricant supply company.
Prior to initial shipment, the lubricant is tested for base-oil viscosity and flash point, additive package composition and concentration known as the “treat rate” and level of contamination (or cleanliness). If the batch meets the lubricant design requirements it is given a Certificate of Analysis (COA), which is copied to the lubricant purchaser. This COA document is important as it acts as a baseline measurement for all corresponding quality checks prior to machine point-of-use.
On the next step of its journey, the lubricant is susceptible to contamination-degradation risk. That’s because bulk oil is primarily moved around the country to supplier “tank farms” (large holding-tank facilities) via tanker trucks. Although there is no across-the-board cleanliness standard for tanker trucks, most lubricant manufacturers do require them to arrive with their tanks cleaned of previous product residue and pass a visual cleanliness inspection and a simple hydrocarbon/gasoline presence “sniffer” test before filling can take place.
Once filled, the tanker truck delivers the bulk oil to the supplier’s facility. Prior to off-loading, though, the truck’s lines and hoses are required to be flushed in accordance with the lubricant manufacturer’s guidelines (these will vary according to the compatibility of the onboard new lubricant with the residue of the previously shipped product). During this process, a lube sample is taken and quality-tested to ensure no product degradation has occurred. From this point, it’s often assumed the supplier’s tanks are clean and no cross-contamination has taken place within the tank, and that no water or solids contamination has been allowed during storage.
The next step can be a lubricant transfer from a regional facility to a local tank farm owned by the supplier. Or there can be a direct transfer to an end-user’s site in bulk form or pre-filled supplier bulk totes, barrels or pails. Again, it’s often assumed the pumping equipment, tanker-truck compartments and lines or containers have been cleaned and flushed correctly. However, based on a supplier’s level of cleanliness, your lubricant may be delivered in accordance to the original COA level of quality or it may not!
- Ensuring lubricant quality at delivery is incumbent on the end-user. The following steps are important:
- Insist on a lubricant Certificate Of Analysis (COA) for each lubricant delivered. Keep this document on file until the batch of product has been used.
- Never assume all lubricants are delivered as per their COA document specification.
- Set up a delivery-acceptance agreement with the supplier to deliver lubricant based on the COA and/or a set of internal minimum cleanliness (see Table I for ISO 4406:1999 guidelines) and viscosity specifications (within +/- 10% of COA specification).
- Establish an oil-quality-analysis test acceptable to both end-user and supplier, and a develop a service-level agreement that outlines the lubricant-condemning levels and remedial-action requirements in the event a product fails the quality test on delivery.
- Perform quality testing regularly, taking a bulk sample after the tanker truck lines have been flushed prior to transfer, and from the center of any supplier pre-filled containers.
Once the delivered lubricant has been accepted for use, the risk of contamination degradation is in total control of plant personnel. Thus, it’s crucial for lubrication personnel to be familiar with the ISO 4406:1999 Code and its Solid Contamination Code Suitability Matrix (Table I).
The ISO 4406:1999 code examines the number of 4-, 6- and 14-micron particles present in a 1-ml lubricant sample and compares them to a particle concentration range to determine the ISO range-number value. For example, a 19/17/14 lubricant value (new oil) translates to between 2500 to 5000 particles >4 microns in size, between 640 to 1300 particles >6 microns, and between 80 to 160 particles >14 microns.
From supplier to point of use
As soon as it’s under the control of a maintenance department, a lubricant must be carefully stored and transferred if it is to reach the bearing surface in the state of quality intended by the manufacturer (or even cleaner if dictated by machine requirements). Figure 1 shows incorrect and correct storage methods.
Storing new lubricants is best achieved in a dedicated lubrication room or crib, preferably indoors. If stored outdoors, lubricant products must be protected from the elements, particularly rain.
Outside drums are best stored horizontally in a drum rack. If this configuration isn’t possible, the drum can be stored upright and tilted using a 2×4 placed under one edge with the fill bung placed at the highest point to avoid surface-water build-up and ingression on opening.
The types of temperature changes experienced in northern climates can cause condensation to occur in a drum. When water contamination is suspected, the oil must be lab-tested (ASTM D1744/D95) for water and for viscosity change (ASTM D445) after opening, prior to use. If +/- 10% of difference is found from the COA baseline, the oil will require centrifuging to extract the water. This situation can be avoided by investing in outdoor drum-storage protection containers or simply by storing the oil indoors.
Since oil has a shelf life, the lubrication technician must track purchases and usage in a logbook. Purchase only enough lubricant for six months or less, and regularly rotate stock using a FIFO (First In First Out) stock-rotation method. (Refer to this month’s “From Our Perspective” column for more tips.)
Within a plant environment, a lubricant is at most risk of solids (dirt) contamination and old-lubricant cross-contamination when being transferred from a bulk container (tote, drum or pail) into a smaller transfer container (oil can or jug) to the machine reservoir. The common culprits are non-dedicated, un-flushed or dirty transfer pumps and filter carts, or non-dedicated, dirty funnels and transfer containers, especially if the container is an open container.
To minimize contamination ingress when storing and transferring lubricants in a plant environment, keep these rules in mind:
- Use only dedicated storage tanks, pumps and transfer equipment, one set per lubricant. Label all equipment with the appropriate lubricant identification.
- Ensure storage tanks (including at-point reservoirs) have secure fill caps and breathers.
- Implement a regular-cleaning PM work order for all tanks, reservoirs and transfer equipment.
- Transfer bulk oil through dedicated filter carts.
- Use quick-connect couplings for pump transfer wherever possible.
- Use one-time disposable funnels. Store them in a sealable plastic freezer bag.
- Avoid use of suction/fill wands.
- DO NOT USE open transfer containers that can double as a watering can.
- NEVER leave lubricant containers open after transfer has taken place.
Performing basic housekeeping and taking a common-sense approach to lubricant transfer will give the lubricant its best chance to do what it was designed to do once it gets to the bearing surface. LM&T