An effective, well-managed and strategically implemented PdM programme can help overcome dysfunctional and under performing production equipment of all types. Fernando Lisboa reports.

The processing of petrochemical products depends on the optimal functioning of multiple complex and failure-prone electromechanical systems. Such equipment includes process heaters, evaporators, crystallisers, solvent recovery systems and tubular furnaces.
The failure of these systems and other types of equipment can result in the unexpected shutting down of critical production lines, increasing costs, necessitating the reallocation of manpower and material, reducing productivity, impacting quality and, if not corrected, threatening profitability.
So what maintenance options are available to decision makers responsible for the optimum functioning of petrochemical facilities? Run-to-failure management is the most expensive method of maintenance characterised by: high spare parts inventory cost; high overtime labour costs; high machine downtime; and low production availability.
Fortunately, the majority of those responsible for the maintenance of chemical processing systems have abandoned the 'If it isn't broken, don't fix it' policy of waiting for equipment failure before initiating maintenance on critical facilities.
In recent years, maintenance decision makers have often embraced preventive maintenance, that is: maintenance based on the probability of failure increasing with increased hours of equipment operation.
All preventive maintenance programmes assume processing machines will degrade within a statistically ascertainable time, the result being either unnecessary repairs or catastrophic failure.
The predictive maintenance (PdM) alternative uses direct monitoring of equipment operating condition, efficiency and heat distribution to determine the likelihood of failure or loss of efficiency for all critical production systems.
Unfortunately, many maintenance decision makers have not fully or faithfully adopted a comprehensive, proactive PdM programme utilising infrared imaging (thermography) and other inspection technologies proven to significantly mitigate and even prevent costly and potentially catastrophic production-critical parts and equipment failures. An effective, well-managed and strategically implemented PdM programme can help overcome dysfunctional and under performing production equipment of all types.
Predictive maintenance programs monitor and record the actual operating condition of multiple processing and supporting equipment so that all maintenance will be scheduled on an as-needed basis.
According to R Keith Mobley, the author of An Introduction to Predictive Maintenance, eliminating unscheduled repairs, and scheduled but unnecessary repairs, means maintenance managers can reduce the need for corrective maintenance by as much as 90 per cent 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 60 per cent and increase manpower utilisation by as much as
85 per cent.
That's not all. PdM programmes have improved production, increased capacity, and established the best production procedures to meet the demand for higher production rates without a corresponding increase in maintenance cost and reduced equipment life. Simply put, better maintenance procedures contribute to defining, establishing and implementing optimum production, increased productivity and product quality and ultimately greater profitability.
According to Mobley, when fully utilised, a PdM programme can generate a return on investment well above 100:1 or $100 for every dollar invested.
Does this kind of effort have a substantial cost? Most certainly. The actual time and manpower required to establish a predictive maintenance programme will vary depending on the size and the complexity of the chemical processing systems. For a small operation, the time required to develop a viable programme will be about three man-months. For large, integrated processing facilities, this initial effort may be as much as 15 man-years.
Are the benefits worth this level of effort? In almost every instance, the answer repeatedly and convincingly has been documented to be an absolute yes. While the cost of a PdM programme is higher than conventional maintenance, consider the even greater cost of just one avoidable catastrophic processing failure.

Thermal imagers

Infrared energy is light that is not visible to the human eye and that people detect as heat. Even very cold objects emit infrared heat that can be 'seen' and recorded as thermal images by infrared thermography imagers that work by aiming the imager much like a regular camera.
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.
The petrochemical refining process consumes great amounts of energy creating high levels of heat which create intense performance requirements on major processing and support systems.
Portable, handheld, non-contact thermal imagers scan and permanently record the temperature and infrared thermal image of crucial petrochemical production equipment as it operates normally.
Data and images are downloaded to a PC, accessed and analysed by software and are available for comparison with subsequent thermal imaging scans. The resulting performance profile of key processing 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 production and related systems.

Infrared imaging can identify problems in a variety of systems and equipment, including electrical switchgear, gearboxes, electrical substations, transmissions, circuit breaker panels, motors, building envelopes, bearings, and
steam lines.
In addition to electrical distribution system maintenance, infrared imagers play a significant role in process furnace maintenance, refractory loss management, tank level verification and condenser fin diagnosis.
Unlike vibration or lubricating oil and wear particle analysis, thermography is well suited to monitor all types of production and processing equipment.
Much depends on selecting the right thermal imager for optimal maintenance. Responsible decision makers should become knowledgeable about the performance capabilities of thermal imaging tools.
Most importantly, they should understand 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 serve the requirements of a large petrochemical production facility well, while an ultra sophisticated, difficult-to-use imager would constitute overkill.
Typical imager problems? Consider such factors as operator safety. Is it necessary for the operator to look through an eyepiece to use the imager? If so, assuring operator safety during equipment inspections may necessitate a safety assistant, doubling the man hours necessary for operation of the unit. Such arrangements quickly increase cost and reduce unit availability. Depending on maintenance budget constraints, requirements for a safety assistant may be a deal breaker, cancelling the purchase of an imager that would otherwise be affordable.
Imager portability. Does the weight and size of the imager affect data collection? Heavy, oddly shaped, overly cumbersome units may require personnel of a certain size, weight or physical condition, to operate the unit, possibly excluding some members of the maintenance staff.
If the imager is awkwardly designed, hard to handle or difficult to aim with precision, the operator may not be able to get physically close enough to optimally scan certain hard-to access-equipment. Do not assume that all imagers are ergonomically equal. They are not. Some are better adapted to the rigours of petrochemical processing facilities.
Temperature. Will you need to measure more than one temperature range? What are the maximum upper and minimum lower ambient temperatures in which the imager will be used? 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 processing equipment. Look for imagers with a maximum upper ambient temperature of 500¼F and minimum lower ambient temperature of at least 32¼F.
Power supplies. How long will the batteries last and how long do they take to charge? 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.
Only imagers supporting data and image downloading for storage and interpretation to any PC are acceptable for a serious PdM programme.
The best, most versatile imaging software is bundled with the imager by its manufacturer and is included in the price of the unit.
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.

To be sure, maintenance decision makers considering the purchase of an infrared imager should look for a vendor who can help evaluate their thermal imager/predictive maintenance needs before purchasing an imager. Vendors should help in determining what will be the time/dollar cost of integrating/expanding thermal imaging into a predictive maintenance programme. The extent to which a vendor has had experience in the petrochemical industry is a definite plus.
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 successful PdM programme is based on a strategy, or blueprint designed by and for a particular facility to help fulfill specific predictive maintenance objectives. A PdM strategy is the day-to-day script needed to utilise thermal imaging and all of the available predictive maintenance tools to achieve positive, verifiable, cost justifiable results sooner rather than later.
Last but not least, a thermal imaging vendor should help petrochemical maintenance managers set realistic expectations about what constitutes reasonable payback and successful operation of a thermal imager used to implement a predictive maintenance programme. There's no need for management to connect the dots when knowledgeable vendors can help identify and achieve manageable objectives.

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Fernando Lisboa is Director of Worldwide Marketing for the Portable Products Division of Raytek Corp, Santa Cruz, CA, USA. www.raytek.com