Mechanical Technology November 2015

⎪ Proactive maintenance ⎪

• Phase angle analysis of motor voltage and current as an alternative to accelerometers. • Wireless hybrid three-axis sensors for vibration; multi- spectrum acoustics; and temperature. Similar developments have been taking place in methods for periodic on-line assessments. Some interesting examples are: • Radio frequency detection and analysis for electrical discharge current (in bearings, seals, gearboxes, etc.); partial discharge; and arcing. • Acoustic stress wave analysis for condition assessment of wooden poles (integrity of pole and anchoring). • Infra-red gas analysis . • Ultrasonic detection for assessing valves; heat exchang- ers; and steam traps. The point being made here is that this is a rapidly developing field and it is quite possible that many unexpected failures, which would previously have been described as ‘acts of God’ can now be predicted with high levels of confidence – and not necessarily at high cost, either. The common thread amongst these is that the technologies are intended to be used while the asset is in normal service and without affecting production. This is becoming more and more important to organisations everywhere, for three main reasons: to avoid loss of production; in the interests of safety; and to avoid incidents of repeated infant mortality. For the purposes of condition monitoring as discussed here, tests are excluded. In this context a test is understood to be a process whereby a stress is imposed on the object under test and the response to the stress is observed or measured . The object may need varying degrees of disas- sembly but is usually isolated for the test and certainly not in service. On the other hand, an assessment is passive in nature by detecting, measuring and analysing signals avail- able from the object by various means while it is on-line and in normal service. This is not to say that tests are not important, just that they are not an option available to the reliability engineer for assessing the health of assets in service. Note that here also technology is making great strides and must be evaluated when considering shut down inspections. I would like to finish 2015 with a word of caution. There is a very real danger that the technophiles in our ranks (and I admit to being one of them) will become overly enamoured with the cleverness and intricacies of truly amaz- ing new technology, cunningly conceived and executed to solve some real world problems that we think we may have. However, the risk is that we (or our organisations) do not suffer from those particular problems. It’s just that we would like to think they do, so we can have the challenge and enjoyment of getting our teeth stuck into something new and exciting. The problem is that unless there are tangible benefits to the organisation, this will not lead to favourable recognition and sustained management support, and rightfully so. Therefore, keep in mind the fundamental rule of physi- cal asset management, that is: have a clear understanding of the goals of the organisation and keep every decision in total alignment with those goals. With that satisfied, taking advantage of the capabilities of new technology can be both stimulating and rewarding indeed. Think of it as unexplored territory to prospect for new opportunities in 2016. q

Mechanical Technology — November 2015

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