Reliability Assessment: A Guide to Aligning Expectations, Practices, and Performance. Daniel Daley

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      Other events that occur in the life of many plants and systems are a modification in service or an expansion. During these events, it is possible that current inherent reliability will be retained; it may also be enhanced or even reduced. As in the situation described in the fictional account above, it is not uncommon to see equipment that once provided a source of redundancy used instead as a source of additional capacity. In the example, a redundant electrical feeder was used as a source of power for new loads. It is not uncommon to see spare pumps placed in parallel service with primary pumps to increase throughput.

      In some cases, this modification will reduce reliability simply by eliminating redundancy. In other cases, as with parallel pumps, in addition to the loss of redundancy, both pumps may actually wear faster because they are working against one another.

      During the development of new facilities, we apply Design-For-Reliability techniques to ensure that the completed product is reliable. We can apply those same techniques during the design of modifications to ensure that the modified facility has an inherent reliability equal or greater than before the change.

Conclusion

      The fictional account provided at the beginning of this chapter paints a fairly gloomy picture of how the reliability engineer’s data is received by members of plant management. In some cases, I am sure it is an exaggeration; in others, it is fairly accurate. Think for a moment about issues in your personal life where you have built a set of expectations only to have them dashed by more accurate or realistic information. For many people, reliability is an abstract characteristic that is based more on luck and good intentions than it is on physical realities and solid analysis. For those individuals, it is often painful news when they learn that their systems and equipment are not reliable and that many of the elements contributing to the poor reliability were results of their own choices.

      In order to minimize the negative impact of this discovery, it is best if the exercise of learning “what you have a right to expect” is accomplished as a part of a proactive exercise. This exercise should be done quite separate from any event resulting from poor reliability. Finding out that you have some opportunities for improvement feels a lot better when you are doing it on your own than when a catastrophic event has occurred and you are being forced to do so by your boss or his boss.

      Independent third parties have little ownership for the programs that have been installed but are ineffective. They are also more likely to tell the complete and undistorted truth than someone who is dependent on the people receiving the report for pay increases and promotional opportunities. Another problem with using someone from inside your current organization is that each and every group has made some contribution to good or poor reliability. As a result, every employee within a plant can be biased in one way or another.

      A comprehensive assessment of “what you have a right to expect” is different from an audit of your current reliability and maintenance programs. It is an evaluation of the effectiveness of all the elements important to reliability in the context of the inherent reliability of your current systems.

      Using the example of an automobile, a concerned father may be willing to pay for the expectation of high reliability for his daughter’s vehicle by purchasing a new car for her. She has few of the other characteristics leading to high reliability (knowledge of how best to operate, maintain, or inspect it), but a new reliable vehicle can reasonably be expected to overcome those weaknesses.

      Transferring the analogy to a system or piece of equipment, few of us have the luxury of replacing an item when it begins to age. In other words, we cannot “buy” reliability the way the protective father did. In most real-life cases, we have a right to expect only the level of reliability justified by our:

      •Good operation

      •Sound maintenance

      •Thorough inspection

      •Thoughtful renewal practices

      In order to have a realistic assessment of “what we have a right to expect,” we must assess our expectations in light of inherent reliability as well as all other choices made over the life of the system or device.

Chapter 2

       Naïve Expectations

       I have always depended on the kindness

       of strangers.

       Tennessee Williams, A Streetcar Named Desire

      The longer I remain involved in the reliability business, the more examples I find of individuals who have little or no idea how reliability works. I have started writing this chapter to describe this problem any number of times, but have been rebuffed by how it sounds when I read it back. I erase what I have written and go back and try to rewrite it in a more positive way. Then when I get through with the rewrite, it sounds more positive. However, it does not then adequately describe the issue. Maybe it is best if I just begin with an apology about the negative tone of this chapter, and then highlight the fact that while the description sounds negative, the problem can be corrected.

      Generally speaking, people take reliability for granted. As described in the quote at the start of the chapter, when it comes to providing reliable systems, many people depend on the “kindness of strangers.” They do so even when it seems foolish to do so. Although reliability saves money over the long haul, it costs more in the short-term. Systems that have a more reliable configuration (e.g., redundancy) and contain more robust components have a higher first cost. If you buy based only on first price, you should not expect that a kind manufacturer will enhance reliability by including better features at no added cost.

      The saying “caveat emptor” or buyer beware precedes the complexity of current technology by millennia. Despite that fact, some complex systems are purchased using minimal specifications and few if any pre-acceptance inspections. This approach to purchasing seems just another example of a situation in which someone believes that others will look after their interests. That may be acceptable when dealing with family or friends, but is certainly naïve in business.

      Let’s be explicit:

      •Many people think they can purchase СКАЧАТЬ