Strategies for Reliability
01/11/2011 Eaton Electric Sales Ltd
In the oil and gas sector, where a plant breakdown or an accident can have huge financial implications, there is an understandably strong emphasis on maximising safety, reliability and performance in every aspect of operations. These three crucial factors are, however, by no means independent of each other. In particular, it is impossible to maximise plant safety and performance without addressing reliability.Reliability is, however, influenced by many factors, ranging from the inherent reliability of individual components to the overall complexity of a plant, its operating conditions and the effectiveness of its maintenance regime. It is, therefore, essential when specifying and acquiring new plant to adopt a proactive approach to ensuring reliability from the outset.
The first factor to consider is ways in which the risk of failure can be designed out. For example, a gravity fed water supply system will always be more reliable than one that depends on pumps, as gravity is unlikely to fail. Simplicity is the next key factor - the fewer components that are used in a system, the less likely it is to fail, all other things being equal. Simplicity should, therefore, always be the aim in plant and equipment design.
Next, consideration should be given to reducing the likelihood of failure by, for instance, selecting components with a known low failure rate, over-sizing the components, and ensuring that they are appropriately rated for the ambient conditions in which they will be used.
The underlying aim of enhancing reliability is to minimise the impact of failures on safety and productivity, so it is also pertinent to consider measures that are intended to deal with, rather than prevent failures. These include containment, so that the influence of the failure is limited, and reducing time to repair by, for example, adopting standard assemblies - such as withdrawable switchgear units - that can be replaced quickly and easily.
Duplication of equipment and building in redundancy also fall into this category as they offer a radical and, unfortunately, costly approach to minimising or even eliminating the effect of failures. These techniques are widely used in the oil and gas sector and they are often appropriate. Nevertheless, careful consideration should be given to the potential benefits before they are adopted.
The underlying issue is that duplication and redundancy significantly increase initial costs and the burden of maintenance. These factors may well be outweighed by the benefits, but that's not always true. A second consideration is that, in some cases, duplication and redundancy may not deliver the benefits they appear to promise.
This is usually because common mode failures have either not been properly considered or are impossible to eliminate. A simple example is where the duplicate devices are installed in the same room and the temperature within the room rises to the point where their normal operation is disrupted. In such a case, the benefits of duplication would be minimal, as the duplicate devices would be susceptible to simultaneous failure.
Optimum reliability is a key requirement for businesses in the oil and gas sector, as it underpins both safety and efficiency. As we have seen, however, achieving optimum reliability is a complex task. It requires the use of equipment that has been designed from the outset with reliability in mind, access to extensive engineering expertise, and an in-depth understanding of the applications for which the equipment will be used. For customers in the oil and gas sector, Eaton meets all of these requirements and is, therefore, a dependable partner for maximising reliability.
For further information, please visit www.eaton.com or contact Electrical: literature-info@eaton.com Hydraulics: infoindustry@eaton.com
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