Infrared thermography—its role in maintenance and loss prevention
Unexpected production interruption is intolerable in today's business environment, in which little time or money is available for taking chances. Sophisticated production processes, just-in-time delivery, and increased productivity demands require using every tool available to prevent disrupting production schedules.
To compete in the global economy, small-business owners must maximize uptime and protect their assets by identifying and implementing state-of-the-art predictive maintenance and loss prevention tools. Infrared (IR) thermography is a nondestructive inspection technique that can pinpoint concerns in industrial electrical and mechanical systems. A professionally administered IR program can identify impending failures in electrical equipment; production machinery; fired equipment, such as boilers and furnaces; and utility supplies and prevent business interruptions.
What Is Infrared Thermography?
All objects emit thermal energy (heat) in the form of electromagnetic radiation in the IR spectrum. The hotter the object is, the more intense the infrared radiation emitted. This radiation is, however, outside of the human eye range. IR thermography is used to detect, image, and measure this radiation. By detecting areas of abnormal temperature, IR thermography can diagnose problem areas and their severity.
Modern IR cameras provide detailed photographs indicating each piece of operating equipment's "heat signature." The amount of temperature rise over the normal operating temperature provides a good indicator of the severity of a problem, such as an overload or imbalance, corrosion, or bad connection. This thermal profile, correctly interpreted, can reveal a great deal regarding the operating condition of the equipment being inspected. See the example in Figure 1. A probable cause and recommended action then can be suggested for each finding.
IR thermography detects a common loose connection on line side of a 480-V starter. This starter controls a critical motor in a refinery. Loose connections can ruin equipment and reduce efficiency.
Why IR Surveys Are Important
IR surveys are an investment in the safety, productivity, and profitability of a facility. Insurance industry loss statistics indicate that more than 30 percent of all fire losses are electrical in origin, resulting in electrical failures being the single most likely cause for industrial insurance claims. And more important to the small-business owner, even if an electrical failure doesn't cause a fire, it can result in equipment breakdown and productivity loss. In today's increasingly competitive world, even a short-term production loss could result in long-term customer loss.
Experts have recognized the benefits of infrared scanning in fire loss prevention. Section 18-16.5 of the NFPA (National Fire Protection Association) "Recommended Practice for Electrical Equipment Maintenance" states: "Routine infrared inspections of electrical systems should be performed annually. Where warranted by loss experience; installation of new equipment; environmental; operational; or load change condition, more frequent infrared inspections, e.g., quarterly or semiannually, should be performed."
In addition to preventing losses, IR inspections can help to extend equipment life. A 10-degree-C temperature rise over the rated temperature can reduce a motor's life by half (see Figure 2) and increase energy consumption substantially. As part of a comprehensive maintenance and loss prevention program, regular IR surveys performed by a properly qualified professional can find problems and allow plant management to schedule repairs when it is convenient, eliminating production upsets and unscheduled downtime, as well as extending equipment life and reducing energy consumption.
Many large and medium-sized corporations have made IR an integral part of their preventive maintenance and loss prevention programs. Most property insurance carriers recommend annual inspections.
A 10-degree-C temperature rise above nameplate rating can reduce motor life by half.
How IR Is Performed
IR thermographic imaging has been available for many years as a troubleshooting tool, but was pioneered for loss prevention in the 1980s. IR surveys allow equipment in failure mode to be detected, identified, and repaired beforefailure occurs.
Performed on operating equipment and machinery, an IR survey is a nondestructive test that does not interrupt normal business operations. Measurements are made:
- While the plant is operating.
- Without contacting the target object.
- With the equipment under full load.
- From a safe distance from energized electrical equipment, rotating equipment, or equipment in hostile environments.
After the survey is completed, a report is prepared and can be delivered on-site in either electronic format or color print (see Figure 3. A comprehensive IR report should include at a minimum:
- Equipment identification and location.
- Specific item or component that exhibits the thermal anomaly.
- Temperature rise and severity of the problem.
- Color thermogram and a corresponding visible light photograph.
- Probable cause and recommended action for each finding to assist in scheduling and implementing repairs.
The average industrial facility often can be inspected in a single day. Even very large industrial plants usually can be inspected in less than a week, depending on the survey's scope.
Studies indicate that, on average, eight or more electrical problems are detected per IR survey in a typical industrial facility. Of these findings, four are minor to intermediate in severity and four are serious to critical.
The average cost savings resulting from identifying eight electrical findings is $14,000 less the cost of the survey and the corrective measures taken. This figure is based on the following averages (Figures estimated from RS Means CostWorks database):
- For minor to intermediate problems, the savings average is $500 per finding
- For serious to critical findings, the savings average is $3,000 per finding
This switch in a main substation shows a 130-degree-C temperature rise on the line side. Failure here would have dire consequences in the steel mill that it feeds.
This does not take into account any costs associated with business interruption, collateral damage if equipment is allowed to run to failure, energy costs, or possible personal injury.
Figure 4shows a detected problem and a cost table for replacing failed equipment.
The table in Figure 5indicates the estimated savings from a comprehensive IR thermography program for a mid-sized company with 20 manufacturing facilities. The indicated savings stem only from the avoided equipment damage and do not include any lost production or energy efficiency.
Estimated Savings for Typical Manufacturing CompanySource: Global Risk Consultants
Choosing a Consultant
Any infrared program is only as good as the results. The right testing equipment is essential for the thermographer to identify, troubleshoot, and present the findings properly in a format easily understood by plant management and maintenance personnel alike so that problems can be corrected properly and in a timely manner (see Figure 6). The right thermographer is a must, because the equipment is only as good as the person operating it and interpreting the results. Finally, choosing the right testing company is essential to receiving a quality product from a qualified vendor at a reasonable cost.
This transformer bushing scan for critical equipment depicts an elevated temperature of 120 degrees C above the adjacent bushing due to an internal fault. Failure would have resulted in substantial downtime.
Several factors should be considered when choosing a consultant for your needs. Accurate data interpretation is critical. For this reason, the thermographer's training and experience are critical. Choose one who adheres to the codes and standards of the NFPA, American Society for Testing & Materials (ASTM), American National Standards Institute (ANSI), and InterNational Electrical Testing Association (NETA) and is certified through the American Society of Nondestructive Testing TC1a standard.
Beyond certification, a well-trained thermographer should be able to observe and comment on not only infrared thermal findings, but also on other loss prevention issues that may impact your facility. Experience is important to identify both thermal and nonthermal issues that can affect a facility.
Your consultant should be equipped with state-of-the-art quantitative thermal measurement instruments designed for precise target resolution and thermal sensitivity. In addition to the IR imager, a digital camera, hand-held computer, and specialized software are needed for interpreting and presenting the findings in a meaningful format. Proper personal protective equipment (PPE) is a must, as is the knowledge of how and when it is necessary.
A relatively new addition to the thermographer's arsenal of diagnostic tools is the airborne ultrasonic translator. A high-quality translator can be used to detect arcing, tracking, and corona on high-voltage equipment. This additional technology enables the consultant to detect potentially severe problems that are invisible to the human eye and even infrared thermography.
The thermographer should use state-of-the-art software to interpret results, present them in a finished report, and download the report directly into your facility maintenance computer for immediate work order generation. The software also should database all findings for future analysis and benchmarking. This analysis can be used to determine the frequency and depth of future surveys and allow the small-business owner to allocate scarce resources most effectively.
The last key to selecting a quality service provider is to investigate the company behind the thermographer. Be sure the company has adequate insurance and liability coverage in place, and request a copy of is valid insurance certificate. Insist the company provide adequate safety training and proper PPE based on new exposure requirements in the National Electrical Code. Require a written contract stating exactly what will be performed, how much it will cost, and how any conflict or dispute will be handled. Ask for references and contact them, or check with your industry association for recommendations. Finally, be wary of ulterior motives. IR should not be used to "get in the door" to sell equipment or maintenance contracts.
Using the latest techniques and technologies, a professionally conducted IR survey can identify potential problems before failure, preventing unexpected breakdown. IR surveys are being used in a variety of industrial, commercial, health care, and retail industries. Typical applications include:
Electrical equipment and systems - to detect abnormal overheating due to loose connections, corrosion, load imbalances, and so forth, in high- and low-voltage equipment.
Mechanical systems - to identify heat buildup associated with friction or mechanical stress in equipment, including gear sets, pumps, motors, and compressors.
Process applications - to image and diagnose thermal patterns in industrial process equipment, such as presses, forming machines, welding machines, and furnaces.
Energy - to locate areas of energy loss or gain to optimize insulation or design efficiencies, such as for building envelopes, roofs, boilers, and chillers.
Infrared surveys have been a mainstay for large industrial and commercial corporations for many years. They can be just as valuable to small businesses looking for a competitive advantage.
Jerry Basta is a managing consultant for Global Risk Consultants, an independent provider of loss prevention services. He can be reached at 630-893-0047 or firstname.lastname@example.org, www.globalriskconsultants.com.
For more information regarding infrared thermography services, please contact FMA