NOT the low hanging fruit of Infrared Thermography

Presented at Snell Infrared Thermal Solutions Conference
Indianapolis, IN. June, 2000
Gregory R. Stockton, President
Stockton Infrared Thermographic Services, Inc.
8472 Walker Mill Road
Randleman, NC 27317
(800) 248-SCAN

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.

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.

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.

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.

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.

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.

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 LNē-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.