The factors which drive resource efficiency are complex, and include raw material quality, operator work practices, machine settings, process set-points and technology. For a given technology, it is important that machines are operated at design specifications. This requires responsible operation and also means that these machines need to be well cared for.
It is a commonly held view that equipment that is well maintained tends to work efficiently. This seems intuitive, but how true is it, and how does plant maintenance strategy and practice impact on resource efficiency? In my experience, there are very strong links, but this opportunity is not being exploited fully by most organisations. The reason for this relates to how individual organisations define “reliability”. Those organisations that incorporate aspects of operational excellence (including resource efficiency) other than uptime into their definition of reliability are best able to leverage plant maintenance in support of superior resource efficiency.
There are some very obvious examples of equipment failure which relate to issues such as water conservation, energy efficiency, waste minimisation and material usage efficiency. Air, water, steam and product leaks come to mind immediately. Failed insulation and refractory linings lead to excessive heat loss (or heat gain in the case of refrigerated processes). These types of failures are dealt with by most organisations through their maintenance management infrastructure, largely because they are readily apparent.
There are however many other more complex and less obvious failures which are typically not addressed. Refrigeration loop condensers become fouled, reducing the coefficient of performance of chiller plants. Bearing wear increases the power consumption of induction motors. Non-return valves fail, causing reverse flow and overflows from boiler hotwells. Worn pump components (e.g. impeller wear on slurry pumps) lead to reduced efficiency and increased power requirements. Capacitors fail, reducing the effectiveness of power factor correction systems. I could go on, but the common feature of these failures is that they do not stop manufacturing plants from producing, and hence do not show up in typical maintenance-related KPI’s. They hence often develop, worsen over time, and generally only receive attention when they reach catastrophic proportions and affect throughput. Their cumulative impact by that point can be enormous. Why does this happen? The reason is related to the definition of reliability, or more correctly the definition of what constitutes a failure.
Modern maintenance practice focuses on the prevention of failure, and there are a range of approaches that can be followed in developing appropriate preventive maintenance tasks. The level of effort ascribed to the prevention of specific failures relates to the consequences of those failures. The larger the consequences associated with an identified failure, the greater the effort invested in preventing it. This effort can include the use of condition monitoring technologies as well as tasks carried out by both plant operators and artisans. The problem though is that most of the failure modes that receive consideration are those relating to breakdowns and safety rather than those associated with the complete function of the machine being assessed.
World class organisations don’t just deal with failures, they deal with functional failures. These are failures which impact on the functions of a component. These functions extend beyond the component simply continuing to operate. This subtle distinction has enormous implications for the nature of the maintenance programmes that are ultimately developed. When resource-efficient operation is considered to be part of the function of a machine (rather than just producing product for example), additional failure modes may be identified for individual components. In addition to this, the consequences of individual failures are viewed totally differently, and hence the maintenance effort allocated for the prevention of failures that lead to resource inefficiency can be significantly increased. This increased effort comes at a cost, but has a material return.
This philosophy requires good cooperation between the operations and maintenance functions, not just in the planning and execution of maintenance tasks but also in the development of preventive maintenance programmes. Quality management systems have become important vehicles for the operationalisation of best practice, and most leading organisations tend to integrate systems designed to facilitate product quality, environmental responsibility, safety, food safety (in the case of food manufacturers) and more recently, energy efficiency. It is vitally important to include plant maintenance into the mix of systems used to drive operational excellence. Computerised maintenance management systems are the ideal tool for the storage and management of the preventive maintenance tasks that drive resource efficiency, along with all other aspects of operational excellence. The mechanisms used to arrive at those tasks is at the heart of achieving superior resource efficiency performance, and here tools such as Failure Modes, Effects and Criticality Analysis (FMECA) and Reliability Centred Maintenance (RCM) are very useful.
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