The profitability of asset-intensive manufacturing companies hinges to a large extent on maximum plant availability with minimal (zero) unplanned downtime. But what is the best approach for the maintenance manager to take in order to achieve this? Every type of plant is different, and their approach will also be constrained by the level of available personnel, the budget, the age of plant assets, and the typical manufacturing cycle. The traditional ‘preventive maintenance’ approach still has its place, but new research indicates that only a small percentage of equipment shows the age-related failure patterns best served by this method. As it turns out, the majority of plant assets can be operated more efficiently using strategies like predictive or prescriptive maintenance, both of which place the organisation higher on the maintenance maturity curve.
However, the move up the curve raises some important questions. If the plant is running well today, is it running the same as yesterday? How do you know? The answer is through some sort of measurement. In response, the variety of sensors available to monitor plant operations have multiplied in number, particularly over recent years, and the software available for data analysis has increased in complexity and functionality, which can also be accessed remotely. The combination of these can now give plant owners the operational information they need to enable optimisation of each stage of the process, along with advance warning of any possible equipment deterioration.
The challenges for the plant manager then become to identify where best to allocate the available budget for monitoring so as to provide information on maintenance related issues, and which plant operations could benefit the most from closer scrutiny to identify methods of improving performance. There are specialists in, and equipment for, many different types of plant and machinery. So the decision becomes whether the identified monitoring can be incorporated into the existing automation using a cots (commercial off-the-shelf) solution, or whether it needs to be separate. If separate, then can these systems be managed by in-house staff, or do they need support from a specialist external operation? (See ‘Leading industrial organisations improve asset management with IIoT’ for advice on how industrial organisations can improve their asset management strategy.)
Off-the-shelf systems can provide immediate benefits
There are many examples of easily installed solutions designed to solve common (and often costly) reliability related issues. For instance, it is almost impossible to detect a jammed or leaking steam trap in real-time as it requires a plant walk-through, and even then problems can easily be missed. No surprise then that many companies have invested in retro-fit steam trap monitoring technology connected to the control system via an industrial wireless network. Such systems are available from Emerson (www.instrumentation.co.za/54239n), Spirax-Sarco and Armstrong.
Another area where advanced warning is a benefit is in the condition of bearings on heavy-duty rotating machinery like pumps, fans and centrifuges. With sensors fitted on the housing, any high-velocity vibration accompanied by an increase in temperature can indicate bearing deterioration. Suppliers like SKF (www.instrumentation.co.za/55967n) and Schaeffler, provide simple Go/No-go alarms, as well as multi-sensor monitoring platforms for equipment as big as wind turbines, all backed by their bearing know-how. Some machines require continuous monitoring, but there are also wireless (self-powered) versions of these sensors that can be moved and placed around the plant as required.
The IIoT puts it all within reach
The ideas of advanced condition monitoring have been around for years, but were always limited by the need for plant-based specialists to analyse the data and detect the changes. Now, thanks to Smart Sensors and Big Data analytical software affordably connected via the Industrial Internet of Things, equipment analysis has become easier with many suppliers offering to monitor their machinery remotely as a service. Some even offer to monitor overall plant performance providing regular reports and recommendations, along with guarantees of maximised productivity and reduced operating expenses.
What we aimed for in this Industry Guide was to present as many as possible of the modern methods and technologies available to optimise overall equipment effectiveness through reliability. Hopefully you will find a few ideas in here to help you identify the best options for your own plant.
Steven Meyer
Editor: SA Instrumentation & Control
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