NOT the low hanging fruit of Infrared Thermography
Presented at Snell Infrared Thermal Solutions Conference
Indianapolis, IN. June, 2000
Over the past fifteen years, infrared thermography has gained acceptance as the way to check electrical circuitry for loose connections and other unsafe and wasteful conditions. This is a proven application and what the majority of infrared service providers do for a living. However, most of us know there are many uses for infrared thermography other than inspecting electrical switchgear. This paper discusses some of those applications as well as some new techniques for performing and promoting traditional infrared thermography.
In 1989, I saw my first real-time infrared image and was so intrigued, that I quit what I was doing and proceeded to spend every dime I had accumulated to operate a ‘business’ where 90% of my sales calls ended with “could you send me something in the mail.” Translated, this means, “don’t send me anything, just go away!” It also means, “I don’t understand” or “I don’t take chances” and/or “I don’t like you.” I persisted and found that I could make a living in infrared thermography by checking electrical switchgear. I sought the training I needed, bought a van and converted it into a self-contained office. After three years in the red, the business finally started to pay me a salary. It seemed the maintenance world had come to terms with the fact that electrical resistance equals heat, heat could be seen with an infrared camera and a useful report could be generated so that repairs could be made prior to equipment failure. Infrared predictive maintenance (IR/PM) has become a regular part of the maintenance of industrial electrical equipment. Damage to the equipment itself was never the issue. The downtime that the equipment failure causes was, and still is, the main motivation for IR/PM programs.
After a few years of looking at switchgear, I was getting bored with it. I convinced my clients to spend a little extra time [money] on mechanical inspections. I soon found out it was more efficient for my clients, if I taught them how to trend temperatures (Teach a man to fish…) on mechanical devices such as electric motors, instead of me coming in with a $65,000 imager every month. I would always make the report cover a thermograph of something in the plant (other than electrical) that I could talk with them about when I formally presented the report and videotape. The videotape contains a time-stamped, infrared image (post-processable) of every piece of equipment that was inspected, whether or not it has a problem. At the end of each job I made a formal report presentation. We still do this often, especially with first-time clients. I want to relieve my company of liability, present my findings formally, and sell others in the plant on the idea of looking at other things. Some bright guys at these plant started having me look at processes and production equipment. I found that often I could not look inside the machine but could see the effects of the machine on the product that it made. The savings from process infrared were tremendous. My clients started buying their own IR cameras. Even though I was no longer needed in that particular plant, I got work from the colleagues of the people that I helped, like the small plant across the street or another plant in the same company. There is no better advertisement than taking a company from no IR predictive maintenance to them operating a successful IR program. The idea is to teach the maintenance personnel at the plant to trend temperatures in a repeatable (if not accurate) manner. By taking the ambient, subtracting it from the high temperature, getting the delta-T and keeping up with it, failures are predicted. With some highly advertised and well-documented savings, the plant personnel could build justification for the purchase of their own imaging equipment.
That was and still is our goal. In our electrical division, we find plants with poor (or non-existent) IR/PM programs and take them to buying and implementing a great program. Since we ‘work’ our way out of the plant and do not sell the equipment, you may be wondering how we profit from this practice. First, every plant does not need or want an in-plant program. Some plants are so small (or unprofitable) that they cannot afford one. Others can afford it, but want a third party to do the inspection. Some, like banking computer centers and others with UPS systems, want an expert with the state-of-the-art equipment to do the inspections because their operation is so critical. Secondly, even plants where we help them to justify the purchase of their own system and implementation of a program, we get paid along the way and paid to consult with them from time to time. Also, as stated earlier, there is no better advertisement than a referral from a company (or another division) that we helped get their own system. Lastly, we sell other infrared services from our other divisions to these companies.
Applications in General
Finding hot switchgear is still the low-hanging fruit of the infrared thermography industry. It is the easiest infrared thermographic service to sell and one of the easiest to perform. Of course, as anyone who has attempted plumbing repairs at home knows, there is a trick to any trade. With a little effort and curiosity many other applications can be discovered. Those who challenge themselves to explore new markets, develop new techniques and improve the body of infrared knowledge will reap the financial and intellectual rewards. With modern infrared cameras, software and computers, infrared thermographers today are almost never limited by the infrared equipment’s ability to measure temperatures or discern differences in temperature. Rather, we are limited by our knowledge of how hot the object that we are looking at should be or how to create a condition that shows us what is happening with the object. Perhaps our only real limitation is our imagination.
In general, there are two ways to make a judgment about what is going on with any object(s). Simply:
Don’t do anything. Watch the object radiate heat.
Create the conditions needed. Either;
Apply heat to the object and monitor the results, or,
Apply heat to the object and monitor what happens when then object cools (this works with applying cold also), or,
Put a heat source behind the object and watch what happens when the heat come through it.
There are variations on these.
I) Process Control/Improvement Applications
While infrared thermography will continue to be an effective means of performing predictive maintenance on electrical and mechanical equipment, I think the future of infrared thermography and the greatest savings in a manufacturing setting are in the area of product and process improvement.
For the sake of argument, let’s say that a plant operating 24/7 has never had an infrared survey and as a result annually experiences 3% downtime. An enlightened and motivated thermographer sets up an extensive IR/PM program. The management and maintenance staffs are totally behind the program and it is a complete success. Plant uptime goes from 97% to 99.5%. This is big money; savings are calculated at $400,000 per year. The same plant has 20 widget machines. Each has a total annual output of 100,000 widgets. A production engineer talks the infrared thermographer into spending a few days of his ‘valuable’ PM time checking out the #12 widget machine. They work together, find and solve some problems. The #12 widget machine now outputs 10% faster with 10% less in product returns. The other 19 machines are adjusted accordingly and the plant goes 10% faster with 10% less in product returns. Savings are $4,000,000, which is ten times that of the savings from the IR/PM program. There are simply more savings to reap on production equipment.
There are some serious problems in most plant settings with allocating the time, money and resources to improving production processes. First, the infrared thermographers usually belong to the maintenance department. They have a certain amount of work to do per week and process improvement applications take a back seat to maintenance issues. Also, the trend is for the predictive maintenance group to handle infrared thermography along with other techniques, i.e., ultrasound, eddy current, vibration, oil ferrography, etc., leaving even less time for trying out IR on the processes. Then there are the universal problems of high turnover of motivated personnel, lack of proper training, production being in ‘competition’ with maintenance and the old standby of short-term thinking management, “we don’t have the money”.
There are many reasons infrared thermographers do not do more process control work. Often, the biggest problem lies with infrared thermographers themselves. He/she may be uncomfortable looking at (or making a judgment on) something they have not seen before. This may be the only machine of its type in existence and there is no book or published standard. Even if they are confident in their infrared skills they may be poor salespersons, unable to convince the management that process control is a worthwhile application. Management understands that IR is a great tool for predicting electrical and mechanical failures, but where is the proof that it will work on the process? It is exponentially more difficult for an outside contractor to get authorization to perform a survey where there are no set specifications for performance.
Just do it
As stated above, there are all sorts of reasons that infrared thermographers do not do this type of work more often. The most popular excuse is that the IR camera they have is inadequate. This problem is not really a problem. Here are some options.
Borrow a camera from another plant or division.
Have the camera manufacturers perform a demonstration survey at your facilities. They are more than willing to do this. They really want to help you. They know how many applications there are. They are looking for companies that have a need for their equipment and someone that will take the purchase request to management with fervor. They need an advocate with some moxie in the plant.
Rent a camera. There are places to rent a camera, with or without the option to buy.
Hire a training company. They will come to your plant, using your or their equipment and help you look at a process and/or set up a program. These people are not only experts at infrared thermography, but also expert at dealing with the IR thermography vs. management issue.
Hire a consultant/infrared contractor. If you know what information you want, know how to get it but do not own a camera that will get it, there are contractors that will for a fee, come to your plant and look at anything you want to look at.
As IR contractors/consultants, we are sometimes hired to go into plants that have an IR camera, but whose IR program is failing. Often, the hero that got the money approved to buy the camera has gone on to other things. The first thing that we do is to find the IR camera system, dust it off, charge the batteries and fire it up. Then we proceed to the air compressor room and to an electrical disconnect or contactor that is burning hot (high loads-always good for a problem), make a picture and go after more stuff that is broken. Then we go to a line of machines and see which components don’t look like the others. Usually, after a few minutes, we find mechanical problems. Next, we follow a process and see what we can determine about irregularities. Often, when looking at the product that has just come out of a machine there will not be an even temperature pattern. At this point, we need the production people to tell us if the uneven temperatures are indicative of a problem with the machine. At the end of the day, we make lots of pretty pictures, print them on glossy paper, make up some MS PowerPoint( slides and review the information in a formal presentation with the management. We get anybody that will listen to attend the meeting. There is no magic here. We have found good reason to keep (or restart) the IR program.
Installing On-line Systems
Some processes need to be monitored at all times. In this case on-line infrared systems are required. The infrared equipment manufacturers are truly needed to find the right system and install it. Unless you have done a very similar installation, you need them to send a real sharp sales engineer. Also, you need to call every one of the manufacturers that could possibly make it work, get them to look at the proposed installation and turn in a proposal. They may try to put a round peg in a square hole, wanting to sell their system. You need to know what type of equipment will and will not work. If you do not know, get someone that does. There is nothing worse than an on-line system that does not work.
II) Research & Development Applications
If successful, many R&D applications are literally worth millions of dollars. Only a small percentage of these techniques and applications are published in forums such as this, because they are tightly held and legally protected secrets. Often it is not as simple looking at something and seeing a defect. Instead these techniques have been developed over the course of years, refined by scientific scrutiny at a cost of hundreds of thousands of dollars. This is where the technology rubber meets the applications road. These people are often limited by more than there imagination. They are limited by the infrared camera’s capabilities. As detector technology advances and specific software is written, there will be even more research done using infrared thermography.
III) Facilities Applications
Today in the United States, most IR thermographers have neglected buildings in favor of other applications. Why? All these machines and the personnel to run them have to live somewhere. Inspecting buildings for heat loss was one of the first commercial uses for infrared thermography.
Building Heat Loss
Let the price of heating oil reach $3.00/gallon and this will become an important issue again. When I went into the infrared business my idea was to look at buildings, and nothing else. In countries where the climate is cold (or hot) infrared heat loss surveys are very important. Also, in very cold climates, poorly installed insulation and vapor barriers can lead to condensation problems and the degradation of the building itself.
There are three types of buildings by use: residential, commercial and industrial. Since residential building owners average moving every few years, they figure that they can live with problems for a while. Homeowners are not usually willing to pay for a survey because there is nothing remedial about infrared thermography and blower door testing itself and they are not going to pay to just to find the problems. High bill complaints are handled by the power company-usually without an infrared camera. Commercial buildings are often owned by one company and leased to another. The tenant is not about to repair a building that he/she does not own. The owner does not care what the utility bills are because they are not paying them. Industrial building owners care about one thing…how many of their products are shipped that day. Unless it affects the bottom line (like a refrigerated warehouse or a building that needs to maintain exact temperature control) most are not concerned about heat loss until it starts to damage the building, affect the operation or make the people uncomfortable. In a plant where 85% of the kilowatts are consumed by machines, the heating/cooling bills are not an issue.
Building Quality Control
Infrared thermography can be used as a building quality assurance tool. Anyone who has ever taken an infrared camera home with them knows that one can see heat loss and air leaks. Also, building components ‘inside’ the walls, ceilings and floors are recognizable because of their differences in mass. Every stud, joist and nail can be found. The problem with the inspection of buildings is not the infrared technology or techniques, it is finding someone who wants the information and is willing to pay for it.
For example, infrared thermography can be used to determine the presence & correct placement of grouted cells in single-width concrete masonry unit (CMU) or ‘block’ walls.
(See Figure 1.)
We ride by, shop in and send our kids to these buildings everyday. Strip shopping centers, malls, schools and many other buildings are often built using CMU walls. Especially with schools, there is a tremendous market potential here. Unlike commercial and retail owners (who can hire anybody they want to build the building), schools are built with government money and mandated to accept the low bidder. The low bidder may not have the money in the job to hire a full-time quality control supervisor. We find many problems with the construction of CMU walls, but judge these defects are almost never caused by fraud. Instead, poor supervision on the job is the cause for the poor quality. Timing is key to the success of many IR applications and CMU walls are no exception. Differences in the mass of grouted, empty and insulated cells, allows the surface temperature to cycle twice over the course of 24 hours.
(See Figures 2,3,4.)
The building owner and/or his structural engineer are the ones that you want to talk with to sell this type of inspection. Others on the job are concerned with constructing the building without delays or problems, so keep this in mind when approaching this market.
Roof Moisture Surveys
An infrared roof moisture survey can help the owner of a roof manage his assets by knowing where the subsurface water is located in the roof. This form of predictive maintenance works well on many types of flat and low-slope roofs. The water usually got into the substrate from a leak, but the purpose of this type of survey is simply to find and document where the water is located in the roof structure. It should not be confused with leak management.
Here are the basics:
At night, areas of roof moisture are warmer, because the latent heat (from daylight sunshine) in the trapped water mass is warmer than in the dry, functioning insulation or roof substrate. After sunset, when the roof’s structure cools down, wet areas of roof insulation and other materials continue to radiate heat because of their higher mass, allowing infrared cameras to detect the sources of heat and record them for later analysis.
We are infrared thermographers, not roof consultants. We map out the heat signatures and let other more qualified individuals do the verification. Once upon a time, we did on-roof infrared surveys. It was difficult to schedule, perform, document and produce high quality reports. Then, we did the verification on the roof because if we had not, we would have often made numerous findings of areas that did not contain water. One can easily be fooled by heat due to other factors such as water between multiple layers, old patches, heavy flood coats, reflective coatings, heat-producing equipment under the roof, heat blowing down onto the roof surface, stains on the roof, heavy build-up of ballast at parapet walls and along edges, etc. We learned that if we did not check them then and there we would be making many incorrect findings. Infrared and visual documentation is time consuming and sometimes dangerous. The best way to obtain excellent imagery is to get high above the roof and look down. This helps avoid reflections and you get a larger area in the picture. To do this, we climbed ladders with (then, state-of-the-art) bulky LN²-cooled cameras. If we were lucky, we tied up three or four people and got 200,000 square feet done in a night. We tried using helicopters. Ferry times were slow, the costs were high, and we had to deal with vibration problems. We have found that by using fixed-wing aircraft together with 512 x 512 (262,144 pixels) focal plane array cameras (as compared to most others with 256 x 256, or 65,536 pixels), we now have the right platform.
There are numerous advantages to performing the infrared roof moisture surveys this way.
Costs are comparatively low per square foot because we fly an average of 10 million square feet per flight, with a crew of two. We can wait for the right night for imaging, and survey many roofs under good conditions.
Aerial imagery is better than on roof imagery, but not because we have four times the pixels. We use up our pixels by flying typically 1,500-2,000 feet above the building. The reason is that by getting a large area of the roof in one view, we have more useful imagery. One can see the beginning and end of a long striation or large amoeba-shaped blob of heat on the roof. This allows us to see lesser and more water, by mass, because we are not standing on top of it.
High-angle, straight down infrared images lessen reflections, eliminate the problem of rooftop equipment being in the way of the image and eliminate the problem of access to multiple levels of the roof.
Plan view imaging allows for the accurate marking of areas of suspect roof moisture contamination onto AutoCAD drawings. The drawings are made by laying the blank AutoCAD ‘over’ the captured visual and/or infrared image on the screen. If dimensional information is available, this creates a quantitative, scale quality AutoCAD drawing of the suspect roof moisture contamination on the roof.
By capturing large areas at once, a high quality report is easier and less expensive to produce. Infrared thermographs, visual photographs and AutoCAD drawings can be made of the roof. As a result, the report is clear, concise and easy to understand.
There are some disadvantages.
Small roofs, far away from the plane’s operational area become cost-prohibitive.
Verification has to be done at some point by a qualified professional. No matter how spectacular the images are they are only signatures of heat. As stated earlier, there are many causes of heat (or apparent heat) on a roof.
If needed, painting of the roof’s suspect wet areas must be made on the roof after the AutoCAD drawings are produced.
Perhaps the biggest advantage of aerial infrared is not its use on roofs that have well-defined areas of moisture at all, but those roofs that are the most difficult to image from any distance or angle. I am referring to the roofs that, for instance, have a lot of ballast, are covered with reflective coatings or ones that for whatever reason are impossible to image from the roof. With high-resolution aerial imagery, slight nuances of temperature can be seen from far enough away to actually see the pattern of heat.
With respect to level of detail in an aerial infrared roof moisture survey report, here are the different levels of reporting, in order of costs. Unedited videotape, edited videotape, printed thermographs
(See Figures 5, 6)
aerial photographs, AutoCAD drawings
(See Figure 7)
digital and printed report. The buyer of this service has the advantage of obtaining any one or all of these report components, with the cost being proportional to the level purchased. Also, since the digital videotape (a record of the roof on that night) is archived, he/she can use this information later, to compare proportional images of that same roof to images from a later date.
The future of infrared thermography is very bright and opportunities seem to be limitless. Unlike many other non-destructive testing (NDT) techniques, infrared thermography is generally visible, immediate and easy to see and explain. These are big advantages when trying to obtain funding for untried applications such as process improvement and research. Having a picture that the plant manager can understand (often, a person with limited engineering savvy) may be the linchpin in the approval process. Many times, I have been walking past a machine, taken a quick glance with the camera and seen something that stops me dead in my tracks. By taking a few moments with the camera and consulting with the machine’s operator and/or a process engineer, I have been able to gain a greater understanding of infrared, open up new money-making applications for my company and benefit an ever more grateful customer.
To the infrared thermographer, the world is one big radiator. The transfer of energy happens everywhere around us and we can see it with eyes no one else has. It is our industry’s challenge to explore new markets, improve our methodology for gathering and disseminating infrared data effectively and efficiently and find new uses for this fantastic technology.
Thermographic Services, Inc.™
8472 Walker Mill Road
Randleman, NC 27317
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