Are you getting optimum value from your investment in thermal imaging?

March 31st, 2014, Published in Articles: EE Publishers

 

Thermography is not just pointing the camera at an object. You have to know what you are imaging and then how to interpret the image.

Thermal imaging is not just about pointing a camera at a switch, a transformer or risky cable connection. As in photography, a “mik en druk”  (point and press) camera cannot be compared to taking photographs with a digital single lens reflex camera – the latter requires skills and understanding of the camera. The same applies to a thermal camera.

Jeanri Mellanby:”Think out of the box when deploying thermograph,  it can deliver far more than just checking an electrical connection”

Jeanri Mellanby:”Think out of the box when deploying thermography, it can deliver far more than just checking an electrical connection.”

“A thermal image is only as good as how well the camera operator understands the process”,  says Jeanri  Mellaby,  thermographer at Comtest, the first South Africa woman to obtain a Level 3 thermography certification. “You have to understand your equipment: there are different cameras, each with its own features and limiting factors. The environment in which the camera is used can influence the quality and the ultimate interpretation of the image. So thermography is not simply buying an expensive camera, it requires training to acquire skills.

“Ambient factors such as temperature can affect the results: for example, if you are standing in a switchyard and the equipment is 3 m away, how is the sun affecting your equipment?  Is there solar loading? Solar loading can thermally affect what you see. I have come across contractors that are not aware of solar loading and that the equipment, when very reflective, can show up hotspots on the image which are not true hotspots. This can lead to misdiagnosing, often resulting in unnecessary maintenance call-outs.

“Proper training is a basic requirement and no one should handle a thermal camera unless they have at least a Level 1  certification.”

There are three levels of accreditation. Level 1 is the most basic requirement anyone handling a thermography camera should have.  During Level 1 training the candidate thermographer will learn the basic fundamentals of heat transfer, infrared theory, how to think thermally and how to interpret thermal signatures. Most importantly, the candidate will learn how to operate a thermal camera. Level 1 certification requires the candidate to have completed 31 hours of training, have at least 210 hours of practical experience and pass a three-part examination which includes a practical evaluation of the candidate’s ability to handle a camera. A Level 1 certified thermographer works under the supervision of a Level 2 certified practitioner.

Level 2 requires around 43 hours of training, a minimum of 1260 hours of practical experience and passing a three-part examination. Typically, a Level 2 certified thermographer identifies possible problems while taking into consideration the safety issues that might be involved, prioritising the fault to be scheduled for repair or recommend the next action to be taken. A Level 2 thermographer understands  infrared radiometric measurements, the methodology and procedures involved.

Mellanby is a Level 3 Snell-certified thermographer. The Snell Group Certification Standard follows the American Society of Non-destructive Testing (ASNT) guidelines for certification. Snell serves on ASNT, ASTM, ISO, NETA, IEEE and NFPA committees, as well as several other national and international professional organisations. This is the most advanced infrared training level available. A Level 3 thermographer is primarily a thermography programme  manager,  who is responsible for the company’s written predictive maintenance/inspection practices, develops the test procedures and severity criteria, determines how often equipment should be inspected, and calculates the return on investment the thermography programme  is providing. A Level 3 thermographer can provide guidance to Level 1 and 2 certified personnel. The Level 3 thermographer is the resource to consult when repeated equipment problems necessitate a review of operating and maintenance procedures, or involve a redesign of equipment.

The actual definition of certification is “written testimony of qualification”, and qualified is defined as “competent.” To become qualified you must gain knowledge and then apply that knowledge over a period of time to acquire the skills to properly perform the necessary task(s). To become certified you must prove your competence directly, in person, to an expert in the field who has the credentials necessary to evaluate your performance.

Mellanby runs the thermography training programme offered by Comtest Technologies and trains Level 1 and Level 2.  “We are vendor-neutral and provide thermography training irrespective of which camera is used.”  There are only a few Level 3-certified trainers in South Africa, with  Mellanby the only woman in the thermography business. As it is mostly men being trained to handle a thermal camera, is she being taken seriously? “I get some strange looks when I walk in but they soon realise that I know what I am talking about and get their undivided attention. Thermography is still not appreciated for the value it can offer, but as more people get training at Level 1 and 2, businesses appreciate the benefits they derive.”

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