As a Thermographer at an oil refinery I am often called on to shoot tubes on our Coker and Crude furnaces.We use a Flir PM390(shortwave)camera with flame filter installed.
I have tried to gain as much knowledge as I can by reading and researching this subject, but I still do not feel comfortable with analysis and setups for this special application.
Does anyone out there know of a good school on this subject alone?
Level 1 school did not cover this subject at all.
I would really like to become more knowledgable so that I can feel comfortable with my analysis when asked.
Any info (papers, classes) would be greatly appreciated.

Thanks,
Robbie K.

Robbie,

I believe Greg McIntosh ran a course on this for Snell Infrared some time back. I know I sat in on a course he did on this topic during their Thermal Solutions conference. I would contact Snell Infrared and see if they are going to have Greg offer this course again--it was excellent.

Rich Wurzbach
Maintenance Reliability Group, LLC
ASNT Level III Infrared and Thermal Testing

Dear Robbie:

The subject of furnace tube imaging and temperature measurement is covered in depth in the Infraspection Institute Level II Certified Infrared Thermographer course.

Our instructors are expert thermographers with extensive field experience on heaters of all types. We can show you how to improve productivity, safety, and profit. For your convenience, we can work with you at a regularly-scheduled open enrollment class or at your facility.

For information on Infraspection Insitute training classes and on-site training, please call 609-239-4788 or visit us online at www.infraspection.com.

We look forward to working with you.

Jim Seffrin, Director
Infraspection Institute

Infraspection Institute

This message has been edited. Last edited by: Jim Seffrin,

It would be great if someone could post some advice on the application right here. That way all the people on the board could actually learn more than where the IR Schools are located and how to contact them.

Search google for IR Schools - this board is intended for information exchange.

Rich and Jim - how about sharing a little knowledge for the subject?

Terry O

Terry, Robbie,

Robbie did not ask any specific questions on the topic, but rather where he could go to get training on the topic. I don't think it is overly commercial or a disservice to the readers of this forum to answer that question. However, we don't want the forum to become a sounding board for every vendor to tout their products when someone asks a question--so I understand your concern. My response was not as a vendor, but as a student. I did a Google search for IR schools, and found that it wasn't very helpful in answering his question about that-perhaps there is another posting board area to address this sort of inquiry?
There are a number of published papers on the topic, but I think that Robbie asks the right question about training. Furnace tube inspections are one of the most complicated and difficult IR applications, and should not be performed by someone with only a Level I training course background or minimal experience with the specialized equipment necessary to perform an effective survey. So I encourage Robbie to continue to pursue a detailed and focused training opportunity from one of the qualified training vendors out there. Once he has that fundamental background in the optics, heat transfer, and radiation physics considerations that are unique and vital to effective furnace inspections, I would encourage review of the published papers on the topic, such as "New method of dynamic and multispectral thermography elaborated for inspection of petrochemical process furnaces" by Piotr Pregowski, et. al., and "Furnace wall-tube monitoring with a dual-band portable imaging radiometer" by K. Irani. Both of these papers are available from the SPIE bookstore. At that point, if Robbie has specific questions to round out his training and review of published material, or encounters operational challenges in his perfomance of furnace inspections, I would encourage posting those specific questions here for responses from the IR community.

Rich Wurzbach
Maintenance Reliability Group
ASNT Level III Infrared and Thermal Sensing

I agree with Rich, this is a deceptively difficult application. It is unreasonable to expect someone to learn this from messageboard posts. I strongly recommend a Level 2 course, also let the instructor know that you are working in this application and that you want more information. Then attend a conference and look for someone working with furnaces and speak to them. There was a very good paper presented at Inframation this year, you should be able to buy the proceedings from ITC.

I agree with both Mr. Wurzbach's and Mr. Berry's comments above. My previous comments and those below are offered not as a vendor, but as a thermographer with over 15 years experience in actually providing these types of inspections for petrochemical refiners from around the country.

Performing infrared inspections of process furnaces or heaters represents one of the most difficult tasks for thermal imaging and infrared radiometry. Accuracy in temperature measurent is of paramount importance since many companies utilize infrared data to determine safe operating limits for in-service heaters. Inaccuracies for any reason, including lack of experience, can lead to catastrophic failures of equipment and fatalities.

Far from being a "point and shoot" application, a thermographer needs to understand heater operation and heat transfer as well as issues pertinent to thermography. These include, but are not limited to: infrared camera selection including proper spectral response and spot measurement size; imager calibration; use of filters, windows and heat shields; calculating emittance and reflected temperature; equipment precision and accuracy; and how to obtain reliable reference temperatures to verify proper imager settings. All of this must be done in extreme environments that often push the infrared imager and thermographer to their limits.

In short, there is simply not enough room on any messageboard to convey all of the information required to perform these types of inspections safely and accurately. Thermographers should be trained to at least Level II and, when possible, work with an experienced mentor until they have gained sufficient field experience.

Those wishing more information on this subject may wish to refer to the article, 'Applications of Infrared Thermography for Petrochemical Process Heaters'. This article was authored by one of my colleagues, Bob Weigle, and may be downloaded for free from the IRINFO.ORG website at the following URL:

http://www.irinfo.org/Articles/article_3_2004_weigle.html

Lastly, my initial post above was intended to provide Robby with a direct answer to his request for "Any info (papers, classes) . . . ". In business, there is nothing wrong with offering assistance, answers, or service when one is capable of doing so. In this case, I am certain we can help.



Jim Seffrin

Infraspection Institute

Guess it is just to complex to talk about here.

Too bad.

Terry O

I do realize this is a somewhat complex application.
I have done a fair amount of research on this in the last couple of years, and I beleive we do a fairly good job at our facility.
In my original post I stated any info,classes,papers.
I have read papers and have a pretty good idea on techniques and procedures,but I am no means an expert.
I think that any forum input on this subject would only help myself and other members to do a better job of applying thermography to furnace tubes so that we could learn from each other.

Just my 2 cents.

Robbie K.

Great thread! Terry, I understand your frustration and also appreciate the honest responses of Rich and Jim. Robbie, I'd suggest the best thing you can do at this point is to either continue to gain experience on your own or find an experienced mentor who can work with you. Certainly I see people leaving our Level I and II courses who I KNOW don't "know it all" but, hopefully, are ready to get hands-on experience that validates what they learned in class (hopefully without making the huge mistakes we warn them can be made).

In regard to working on your own, I would URGE you to approach this with great care and precision. When making radiometric measurements in this environment, even small variations in emissivity and background temperature (as well as in our corrections for same), can yield errors that are unacceptable. As Jim stated so well,to make mistakes "can lead to catastrophic failures" and I know you don't want to go there!

The difficulty on learning on your own is that you may not recognize the errors you are making or their ramifications. You can get an idea of this by changing both emissivity and background while staring at a target in the furnace. Note how much the apparent temperature changes.

Even estimating the tube emissivity is a challenge. It can vary from time to time and from one location in a furnace to the next. The paper Jim refers to (Weigle), by the way, is very good and speaks to this fact. Another excellent paper was presented last year at our Thermal Solutions conference by Tony Rolland (Condition Monitoring (trending) Histograms, Isotherms, & Angle of View), Interestingly, Tony as extensive experience looking at furnaces of all types in Australia and, essentially, the more he looks the more numerous his questions also get! This may sound like an oxymoron but the fact is his questions, while more numerous, are also getting BETTER and that has allowed him to learn!

The classic technique for measuring emissivity involves viewing the thermocouple and adjusting the camera's correction until the temperatures register. This can work, but it too is highly susceptible to error and poor repeatability.

The furnace itself also can have several different background temperatures depending on which side or level you are looking at. Again, inputing the wrong correction value makes a significant difference when dealing with high temperatures/radiances.

The issue of atmospheric attenuation and emission is also significant. Two more variables are contributed by the fact that this is simultaneously both a radiant and an attenuating atmosphere which also varies depending on the fuel firing the furnace.

I know many people are using thermography for inspecting furnaces. Honestly, I wonder how well any of us are actually doing! I suspect that much of the work is simply not accurate much of the time but this fact slips because no damage is done or, when it is, can't be tied back to the inspection.

I might suggest, if you are game, that you post any images you have questions about along with the details of the situation. Others MAY be able to give you more feedback although I respect some may choose not to due to the complexity of the situation.

Keep us posted and thanks for prompting such an interesting thread.

Robbie,
I was also a refinery IR tech for a few years and have quite a bit of furnace experiance. One question I would ask is, what kind of furnace? For example, Hydrogen, De-sulf, Coker? They are different.
I did not read where you stated your training level, have you had a level 2 class yet?
It does not sound as though anyone else is prepared to actually explain any techniques, lots of theory though.

Those that do, do... those that can't, teach.

Send me a detailed email and I will help as I can.

I don't mean to be snide, as you are absolutely correct about some trainers. In many other cases, however, "those who are doing" may not realize they have been doing it wrong. And given the complexity of the application and lack of comprehensive information, this should not be surprising!

By the way, there is a great deal of interest in and support for developing a standard methodology for these techniques through an ASTM infrared-related committee. Any interest from the group in pursuing this? Normally the process takes 18-24 months, so it isn't fast, but, once complete, it can have a substantial impact on how things are done worldwide.

As Rich points out there are a few article published but nothing I would consider comprehensive enough to result in a standard and, unfortunately, a few contain misleading or incomplete information. If any of the readers here are game and knowledgeable, let me know and I'll pass the information on to others on the Committee.

quote:

I suspect that much of the work is simply not accurate much of the time but this fact slips because no damage is done or, when it is, can't be tied back to the inspection.

I agree with John Snell on that issue. Most people that do this are not as accurate as they think they are.

quote:

The classic technique for measuring emissivity involves viewing the thermocouple and adjusting the camera's correction until the temperatures register. This can work, but it too is highly susceptible to error and poor repeatability.

I would say, ALWAYS leads to error and poor repeatability. This is one of the biggest challanges with this application. It is very necessary to understand fully how thermocouples work and why your results often cannot match the measurements taken with the thermocouple.

I still stick by what I said earlier on. Go to a Level 2 class and get yourself along to a conference, bring some of your work with you and speak to poeple.

I have read with great interest the notes on this subject. Yes I agree it is one of the hardest jobs to complete accurately. I have spent time in laboratories where a sample can be analysed and the results presented ± 0.5%. This is not the case with furnace thermography. There are SOmany variables to be considered. Is the subject tube near the bottom, below the flame, is it part way up and likely to suffer flame impingement and radiant energy - (reflections), or near the top convection heating. And, as others have noted the emissivity of the tube can vary considerably. I understand that new 5% chrome/alumel steel tube at furnace temperatures has an emissivity of 0.91. This of course will change as the surface ages, suffers flame impingement and scale build up. When I am looking in a furnace set the camera to a Tambient approximating the temperature of the refractory. Then, I capture my images, ensuring I have as many thermocouple points as possible. From the control room i obtain a printout of these thermocouple temperatures. Back in the office I download the images then place a spot next to each thermocouple point and adjust the Tambient to a value so the spot temperature = the thermocouple temperature. I set the TAtmosphere to 30°C - I am using IRwin software. Then I average all the Tambients and use that value throughout the analysis of the furnace. I have a high degreee of confidence with the delta T valuse within each image. However the absolute temperatures give me concern. I look forward to comments. And, thank you John for your note.

Found this appliation note PDF on the web by Ron Lucier of ITC. It provides a very nice explanation of this application for those of us not certified to level 2!

Terry O

ITC_Tech_Note-Furnace_tubes.pdf (252 Kb, 23 downloads) ITC Tech Notes Furnace Tubes

Maverick Inspection also has some interesting stuff posted on Furnace tube (and more) inspection here:

Furnace Applications

Terry O

And another FLIR paper by A.J LeClercq.

Terry O

2003_LeClercq_FINAL.pdf (157 Kb, 16 downloads) IR Tube Inspection

And to complete this series - a group of thermographers who seem to have this application down pat.

IT Imaging





Terry O

Robbie

I echo John Snell's request to post a few of your own images and let us discuss them. Jim, Rich, Bob and John would all teach us a great deal about this application if we give them something to work with.

Thanks.

Terry O

Terry,

Almost anyone can point an Infrared Camera at a target and get an image. However, the key is in deriving the right information from that image that leads to an accurate diagnosis and the proper corrective action. That you copied some images from a website and declared that these guys "have this application down pat", shows me that you just don't get it when it comes to this application. As much as I would like to be able to forgo all the expensive training, and become fully educated by visiting websites, it just isn't going to happen.

I think it is important that we are able to draw the line between valuable information exchange on a message board, and the value derived by attending training classes. It is disingenuous for technology trainers to refrain from discussing certain topics by claiming that they can only be learned by attending their training classes. Likewise it is equally disingenous for message board moderators to claim that the training isn't necessary and that if the experts would just be willing to discuss it, we can train the world one message at a time. I don't believe that either of these cases are happening here, but we do need to recognize the value of both quality training classes, and the important information exchange that takes place online. I really believe that both are needed to effectively communicate complex issues such as this application, and to truly advance the state of this technology.

When someone with only a Level I training course asks for insight on furnace tube inspections, the responsible reply is to seek a Level II training class that will address the specific skills needed to perform this inspection correctly. And if you look at the original posting, that is a key component of Robbie's question--where can I get the training that addresses this application; who has attended one that they thought was good on this topic. I look forward to Robbie posting some of his images and experiences on this board so that we can comment and help him address some of his specific challenges and applications. That, coupled with a training course that gives him the background on performing such inspections, will certainly aid in ensuring that IR is properly applied in this application. And as he and others share their experiences and questions on this topic, we will all become more proficient and educated.

When I started performing IR inspections, they handed me a very expensive camera, sent me to an extremely poor training class, and turned me loose. I was able to find a few things, but I was also often wrong. I would have been better off if I had attended quality training right off the bat, and not had to learn by making mistakes. My shortcut around IR training was through trial and error. I hope that others don't think there is a shortcut around IR training by reading internet postings and websites.

I was able to correct my training deficiencies later by attending quality training, conference workshops and presentations, reading books and magazines, like Uptime and Reliability, reading online forums like reliabilityweb.com, and communicating directly with my peers. All these sources together have helped to round out my experience, and allowed me to achieve ASNT Level III certification.

John, although I don't have as much experience in furnace inspections as others (Tony, Gene Jennings, etc.), I'd be glad to participate on the ASNT committee.

Also, perhaps this discussion can lead to some collaboration to produce some peer-reviewed quality papers on the topic. Maybe we'll even see some presented at the next IMC or PdM conference. That along with an ASNT standard can go a long way to raising the bar on quality in furnace inspections.

Rich Wurzbach
ASNT PdM Level III Certificate #117658
Maintenance Reliability Group, LLC
rwurzbach@mrgcorp.com