Machinery Lubrication magazine published by Noria Corporation
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30 Reliable Plant Annual Edition | www . reliableplant.com ASSET RELIABILITY possible during the lifecycle of the asset. An asset could be a room in a building. An asset could be a chain saw that gets issued out of inventory, returned for servicing and put back on the shelf awaiting the next fire mission. An asset could be a field service truck that requires preventive maintenance such as oil changes, which you farm out to the local garage via contract. e bottom line to what an asset is just that: assets are the phys- ical things that either enhance or detract from the bottom line of the company. By keeping them operational or by disposing of or replacing them at the right moment, the business benefits. ese are considered your assets. THE DIFFERENCE BETWEEN ASSETS AND RELIABILITY e term reliability is a well-defined and understood term. An easy definition is the percentage of "trouble-free" time you have with a piece of equipment. If a piece of equipment has been operating for 10,000 hours and has only been down for 1000 of those, then we can state that it is 90% reliable. It's the definition of that "down" time that is important. Being "down" for preventive maintenance would not go into those 1000 hours. Being down due to defined failures would. Another way to look at reliability is the probability that the equip- ment will survive long enough to perform its function(s). At any point in time, what is the chance that the device will be in-service? No matter how you mathematically arrive at the reliability of a piece of equipment, there are two important considerations: • Is the percentage of reliability acceptable? • Is doing anything to increase it cost-prohibitive? If a pump is deemed to be 95% reliable, does it matter? What does that mean to the business? Does that 5% loss of service translate into millions of dollars in lost production or fines? Don't panic if the calcu- lated reliability of a device is less than perfect — they all will be. Kind of a side topic is that of redundancy. If you have two pumps, both with 95% reliability, but the system only needs to use one at a time, then your system has very high reliability due to redundancy. In this case 95% reliability per pump is very good. Let's stop a moment and go back to the mathematical aspect of this. To do math, you need data for your formulas. If you want to even come close to establishing a reliability number that has any degree of confidence, then you will need to be collecting data that supports your calculations. How are you collecting downtime, in your context? Given there will always be variation in data captured in the field, how are you accounting for this? ere is nothing worse than coming up with a 95% reliability result for a pump when you only have two downtime events recorded, when you know there were more. It's all about the data, folks. And there are many software tools to help not only capture good data but to also visualize and gain insights from raw data in the field. It has been stated that incremental changes — fractions of a percentage point of reliability increases — are very expensive to achieve. is remains true. Making it a goal to increase equipment reliability sounds good on paper, but it will cost you. One of the best ways to increase equipment reliability is to acquire new equipment. at can be an expensive endeavor, but it might be less costly in the long-term than trying to eke out another percentage point of reliability from the 30-year-old pump. WHAT ASSETS ARE "An asset could be a room in a building. An asset could be a chain saw that gets issued out of inventory, returned for servicing and put back on the shelf awaiting the next fire mission. An asset could be a field service truck that requires preventive maintenance such as oil changes of which you farm out to the local garage via contract. The boom line to what an asset is just that: assets are the physical things that either enhance or detract from the boom line of the company." BACK TO "ASSET RELIABILITY" Let's put these two terms back together and see what that phrase means to us now. Assets, those things we care about, cost money to own, may not be perfect and will likely fail at some rate that we may or may not have control over. Gee, that's a fun thought. We all have that "old reliable" thing that we go to when the chips are down. Ever wondered what makes that rusty old thing such a big help to us in bad times? Well, a few aspects come to mind: • Simplicity • Understanding of its use and limits • How it was put away the last time it was used ere was a time when starting an engine was just a series of manual turns and twists of the controls. Now, all it takes is a push of a single button and letting the computers do all the work. Is the equipment itself simpler? Perhaps not, but what it takes to operate is, and that lends itself to sustained high reliability. One caution when it comes to evaluating the reliability of a piece of equipment is attributing its failures to it itself or the supporting equip- ment around it. Is a failed fuel pump charged against the generator or the fuel system? One can argue either way.