Unexpected malfunctions of critical operating systems dramatically increases costs, necessitating the reallocation of manpower and material, reducing productivity and, if not corrected, threatening profitability. Fernando Lisboa reports.

In the world of 21st century global competition, maximising efficiencies to increase productivity is most effectively achieved as a function of a comprehensive predictive maintenance (PdM) programme.
Utilising infrared imaging (thermography) and other inspection technologies, PdM can help mitigate the impact of, or prevent entirely, failure-prone electromechanical systems from going off-line.
According to R Keith Mobley, the author of An Introduction to Predictive Maintenance, eliminating unscheduled repairs, and scheduled but unnecessary repairs, means manufacturers, processors and generators can reduce the need for corrective maintenance by as much as 90percent over five years. Mobley asserts that a successful PdM programme will reduce the life cycle cost and extend the useful life of critical systems by up to 60percent and increase manpower utilisation by as much as 85percent. When fully utilised, a PdM program can generate a return on investment well above 100:1 or US$100 for every dollar invested.
A successful predictive maintenance programme does require thorough and comprehensive monitoring of all critical production systems to determine a base line operational profile against which suspected operating anomalies can be measured, identified and corrected. While the cost of a PdM programme is higher than conventional maintenance, consider the even greater cost of just one avoidable catastrophic manufacturing or power generation failure.

Thermal imagers

Heat is often an early indication of damage or malfunction that can lead to failure or safety problems and is a major performance value monitored in a PdM programme. Portable, handheld, non-contact thermal imagers scan and permanently record the temperature and infrared thermal image of crucial equipment.
Data and images comprising equipment profiles are downloaded to a PC, accessed and analysed by software and are available for comparison with subsequent thermal imaging scans. The resulting performance identification of key production, processing and power generating components enhances the ability of the PdM programme to effectively and accurately predict when necessary maintenance should be scheduled.
Infrared imagers monitor the thermal efficiency of critical process systems that rely on heat transfer or retention; electrical equipment; and other parameters that will improve both the reliability and efficiency of all plant systems.

Dysfunctional pumps

Infrared imaging can detect dysfunctional pumps, under performing surface heat exchangers and identify problems in a variety of plant systems and equipment, including electrical switchgear, gearboxes, electrical substations, transmissions, circuit breaker panels, motors, building envelopes, bearings, steam lines, and process systems that rely on heat retention or transfer.
Unlike vibration or lubricating oil and wear particle analysis, thermography is well-suited to monitor all types of production and processing equipment. Multi-functional, low cost thermal imagers are now priced well below their predecessors.
The effectiveness of a predictive maintenance programme depends on decision makers becoming knowledgeable about the performance capabilities of thermal imaging tools. Note the trade off between imager functionality and ease of use. Even a thermal imager with nominal functions that requires minimum instruction for maintenance staff use may well serve the requirements of a large production facility, in which an ultra sophisticated, difficult-to-use imager would be unnecessary.

Operator safety

Consider imager operational factors such as operator safety. Is it necessary for the operator to look through an eyepiece to use the imager?
If so, assuring operator safety during inspections may necessitate a safety assistant guiding the imaging operator, as he methodically scans equipment throughout the facility. Should not that safety guide be assigned to more important duties?
The weight and size of an infrared imager may affect data collection. Heavy, bulky, cumbersome units may require personnel of a certain physical condition, possibly excluding some members of the maintenance staff. If the imager is oddly shaped or awkwardly designed the operator may not be able to get physically close enough to optimally scan certain hard-to-access equipment. Don't assume that all imagers are ergonomically equal. They aren't.

Of great significance is an infrared imager's ability to measure a range of temperatures. Some equipment normally runs hotter than other equipment. An imager incapable of scanning machinery above a certain temperature may not be suitable for some or much of a facility's most important production or processing equipment. Look for imagers with a maximum upper ambient temperature of 260°C and minimum lower ambient temperature of at least 0°C.
Battery operating life may be crucial to the ability of an imager to get from point A to point Z while on the job. Imagers with batteries allowing for only three or four hours of operation will not function over the entire duration of an eight hour shift. Find an imager that will stay the course, especially if the batteries require overnight charging. Do not pay extra for software compatible with a thermal imager. The best, most versatile imaging software, is bundled with the imager by its manufacturer and is included in the price of the unit. Only imagers supporting data and image downloading for storage and interpretation to any PC are acceptable for a serious PdM programme. Answers to these and related questions can be found in the imager's user manual, which should be available for downloading from the manufacturer's web site.

Operating questions

Maintenance decision makers considering the purchase of an infrared imager should look for a vendor who can answer not only specific operating questions, but help evaluate their thermal imager/predictive maintenance needs before purchasing an imager. There is no need for decision makers to connect the dots when knowledgeable vendors can help identify and achieve manageable objectives.
A thermal imaging vendor should help set realistic expectations about what constitutes reasonable payback and successful operation of a thermal imager used to implement a predictive maintenance programme.
For instance, many production lines have downtimes exceeding US$10000 an hour. With new affordable imagers available, payback in this case is nearly immediate.
Working with detailed payback information that should be available from the imager manufacturer, maintenance decision makers, in consultation with their corporate controller, can calculate a realistic rate of return on initiating or expanding a thermal imaging capability.

Strategy

Once a purchase is made, that same vendor should be ready and willing to help develop a strategy for the optimal use of a thermal imager within an existing or to-be-established PdM programme. A PdM strategy is the day-to-day script needed, utilising thermal imaging and all of the predictive maintenance tools available, to fulfill specific predictive maintenance objectives and achieve positive, verifiable, cost-justifiable results sooner, rather than later.
For some, the commitment to a comprehensive predictive maintenance program will be incremental. For those not yet ready to commit to a full PdM effort, the availability of low cost/high performing thermal imagers can immediately facilitate valuable production equipment monitoring, data acquisition and many maintenance efficiencies, more than paying for the cost of the imager. As a good first step, thermal imaging will obtain initial results in the shortest time at the lowest cost, while positioning maintenance decision makers for the future establishment or expansion of a predictive maintenance programme.

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Fernando Lisboa is Director of Worldwide Marketing, Raytek Corporation, Santa Cruz, California, USA. www.raytek.com