Your lubricant suppliers have a problem.
Lubricant users want their products to be delivered in a pristine state (no particulate, no moisture, chemically uniform, chemically correct). The handling process between the blend-plant discharge pipe and the end-user receiving container can be isolated to prevent contamination by the handling process itself. Drums, kegs and pails can be coated to improve container cleanliness. The lubricant can be delivered through a high-quality filter to the customer's permanent tank. Each of these steps cost the lubricant manufacturer a fair bit of money.
The problem is this: if the in-plant storage and handling practice has a tendency to contaminate the lubricant while the lubricant is being stored and applied to the machines, the added value of delivering perfectly pure lubricant to the site is lost. And, since most manufacturers (machine operators) do not have an expressed reliability agenda that supports a 'clean lubricant' initiative, most of the customers would not be willing to cover the added cost in the form of a price increase. Clearly, the lubricant manufacturer is between a proverbial rock and a hard spot. With that as the backdrop, it is difficult to imagine a lubricant company senior manager, regardless of where he/she works, committing company resources to solve a problem for which the company will receive no benefit.
Consequently, if the lubricant user's company reliability initiative specifies clean and dry lubricants for the machines, then the best approach is for the user to handle this challenge internally. Fortunately, this is not a difficult thing to do once all the personnel decide to make it happen.
Grading Lubricant Handling
Improvements in the handling practices will produce little value if the storage mechanism is unstable. A useful first step is to make sure that the storage process itself is not increasing lubricant contaminant loads. There are different stages of storage. Most sites have a common storage depot for all lubricants, which also serves as a staging area for in-plant stores, and is generally centrally located to all the work areas. Additionally, most sites' open-stores inventory is staged in the middle of a harsh production environment.
These in-plant storage areas need be isolated from production hazards: extreme temperatures, process chemicals, contaminants, moisture. Once this is accomplished, the methods for handling the lubricant are next to be considered. Again, before the any contaminant removal effort is expended, it is appropriate to verify that the lubricant will be maintained in a clean state while it is on the way to the machine sump. Sealable containers designed for this purpose are widely available.
Lastly, contaminant ingression at the machine must also be controlled. Obviously, the machine seals and surfaces should be maintained in a clean and leak-free state. A simple rule of thumb can be used to decide if a seal is in good working order: if oil is leaking out then the environment is leaking in. The problem of ingression will be addressed later in the survey.
Lubricant Delivery
Lubricants are customarily delivered in 55, 15 and five gallon sealed containers, or in semi-bulk (typically 5 to 10 drum quantities) containers, or transferred from of a truck into a stationary vessel at the plant site. Let's first consider the semi-bulk and bulk deliveries.
Bulk lubricant vessels / containers tend to be permanently established in a given location due to dyking requirements, versus being filled and stored full in one location and moved to replace an 'empty' at another location. The reason is fairly obvious: free water is likely to settle to the bottom of a multi-drum vessel, where it waits to be drained into a 5 liter jug for delivery to the machine.
Indoor, climate controlled storage is ideal. Lubricants do age in storage. The rate of aging is 8 times greater for lubricant when stored in direct sunlight (129 °F) versus in indoor, climate controlled environment (75 °F).
Bulk containers are fitted with breathers to allow air to flow in and out when oil is drained or added. It is important to make sure that the breather opening does not come into contact with rain, washdown, or process water during the course of normal storage and use. If the breather comes into direct contact with water then it is likely that the seals (for man-hole type openings) or threads (for screw-down type openings) on the bulk containers will as well.
Obviously, the container should be clearly marked by type and brand of lubricant. Sites that maintain bulk containers tend to maintain bulk containers for several lubricant types. Preferably, the site has a company specific lubricant designation system, and uses this system to mark the vessel contents. A drum label from the manufacturer makes an obvious and clearly recognizable container label in the event that the there is no private lubricant designation system.
Lubricants do have a shelf life. A target of three years for greases and one year for fluid lubricants is both conservative and practical. A packaging date is provided with most packaged products, but the date must be assigned to (noted on) the vessel for bulk deliveries.
All pre-packaged lubricants should also be delivered to a climate controlled storage area. If this is not possible (it rarely is convenient, but is often possible), then at the VERY MINIMUM the lubricant should be stored in a dry area. There must be no opportunity for water to accumulate on the top of the drum. Water will find a way into the container, regardless of how well sealed the container appears to be.
As was previously noted, most packaged products (55 gallon drums quantities and smaller) have a date of packaging stamped on the label. This is required by the lubricant manufacturers at their blend plant sites, and is a practice expected to be maintained by the local packaging agent as well. If a date is not clearly visible then the purchasing agent should inquire into packaging practices and have this detail added to the process.
The date of receipt of the container should also be noted on the container to help with inventory turns and product aging concerns.
The lubricant containers are marked with the plant coding system for tracking the date of receipt and designating a use point.
Lubricant In-plant Storage Practices
A minimum - maximum (min-max) should be calculated for each product type, and largely based on usage. This then should become the target stores value against which inventories are routinely adjusted. Min-max lubricant volumes can be based on multiple criteria. A few suggested criteria would be:
1. The volume necessary to fill the largest reservoir of a designated lubricant.
2. The volume expected to be lost to leakage in a specific time frame of a designated lubricant.
Neither approach is necessarily right. If the lubricant supplier is on the other side of the fence from the plant then the amount of in-plant stores might be only what is needed for convenience. On the other hand, if the site is in the middle of the Gulf of Mexico, and the likelihood for re-supply is weeks rather than hours or days, then the min-max volume will be largely dependent on the risk of having a catastrophic loss. If a 5,000 gallon hydraulic system line routinely breaks and dumps 3,000 gallons overboard, then the amount of lubricant maintained on the rig must be high enough to fill the need while waiting for a delivery.
Keeping with the concept of the lubricant lifecycle, the inventory should be routinely ‘turned' or used up to prevent any lubricant spoilage. This is an easy process if the package and/or delivery dates are noted on the containers. For bulk containers that are filled on-site, the thought is that the lubricant is continuously refreshed, and turning the total volume is less critical. Additionally, most bulk containers are high-usage products that will naturally turn at a higher rate anyway.
FIFO means First-In, First-Out, meaning the oldest container is used first. LIFO means Last-In, First-Out, meaning the last container to arrive is used first. LIFO is a common turn practice. This occurs because the last container to arrive is often the one that is closest to the exit. The site needs a policy for stock rotation that all employees responsible for retrieving lubricant stocks understand and support.
Lubricants stored anywhere in the plant must be behind a containment system according to federal EPA requirements. Traditionally containment was only required for bulk lubricants, but recently containment has been modified to include smaller containers as well. If state EPA criteria are more constraining, then state guidelines have precedence.
Semi-bulk containers tend to get very dirty over time. Dust, dirt and process chemicals all contribute to the outside of the tank becoming crusted and coated with atmospheric contaminants. Coincidentally, the interior of the tanks also becomes contaminated, but at a different rate. All tanks, including the large permanently mounted tanks, should be periodically opened, cleaned out, and then flushed to prevent a heavy accumulation of silt and debris.
As a matter of practical consideration, lubricant-handling tools should be isolated from the production atmosphere to help keep them clean. Additionally, anyone that has ever requisitioned a clean container for handling lubricants and left them un-guarded for more than a few hours can verify that these utensils can grow legs and walk away. A lockable cabinet is a good solution.
Some lubricants are so incompatible with others that even tiny amounts of mixing can create problems. Significant incompatibilities exist with some commonly used synthetics base oils. This is also the case with combustion engine oils and industrial lubricants. Engine oils contain additives that disrupt the ability of industrial oils to shed water. Clearly marked utensils will help to minimize innocent mistakes.
When the lubricant container is filthy it is sub-consciously difficult to imagine that the whole ‘cleanliness' initiative is important. The Oil SafeTM and other types of plastic containers, can be periodically washed in a dishwasher to improve their respective interior and exterior cleanliness.
Opened lubricant containers are sometimes called open-stores. The number of opened containers should be held to a minimum to minimize the time that any particular container is in an open state, with an increased risk for increased contamination. As a matter of policy or simply ecological and economic practicality, it is best to limit the number of a given product and package size to only one container at a time unless there is some strongly prevailing reason to do otherwise.
Clean, dry lubricants both last longer and protect the components more effectively than even moderately dirty lubricants. New lubricants contain between 50 an 100 parts per million of solid material based on particle counts of new lubricants from bulk tanks and drums. As the lubricant viscosity grade increases the lubricant's tendency to hold dirt also increases. Simultaneously, the difficulty of filtration increases as the viscosity increases.
Summary
Take a few moments to think about and <a href='http://www.zoomerang.com/survey.zgi?p=WEB226HT9LJ83Q'>score your own plant program.</a> At the end of the series we will compile the scores and give you a chance to see where you stand versus other industries and production facilities.
Please email your questions to me at: mjohnson@amrri.com. I would be please to help you through this process.
You can learn more about the Lubrication Practices benchmarking project at Maintenancebenchmarking.com
