What is Thermography??

Infrared thermography is an excellent monitoring tool used to reduce maintenance costs on mechanical equipment. The technique allows for the monitoring of temperatures and thermal patterns while the equipment is online and running under full load. Most mechanical equipment has allowable operating temperature limits that can be used as guidelines. Unlike many other test methods, infrared can be used on a wide variety of equipment including pumps, motors, bearings, pulleys, fans, drives, conveyors etc.

Infrared thermography is an electronic technique that quite literally allows us to see thermal energy. Plant maintenance personnel have recognized infrared thermography as one of the most versatile and effective condition monitoring tools available today. Thermal imaging enhances a company's ability to predict equipment failure and plan corrective action before a costly shutdown, equipment damage, or personal injury occurs.

All mechanical systems generate thermal energy during normal operation which allows infrared thermography to evaluate their operating condition. One of the biggest problems in mechanical systems is excessive temperature. This excessive heat can be generated by friction, cooling degradation, material loss or blockages. An excessive amount of friction can be caused by wear, misalignment, over or under lubrication and misuse.

Since most equipment or processes are designed to eliminate thermal energy under normal operation, simply identifying a thermal pattern does not mean a problem has been located. The thermographer must be familiar with the mechanical components being evaluated. Once a normal thermal signature is obtained and understood, any deviation from this normal signature will then provide evidence of a suspect problem developing.

In mechanical applications, thermography is more useful for locating a problem area than for indicating the root cause of the overheating. The heat is usually produced within a component that is not visible directly to the camera. That heat must conduct up through the material and present itself as a pattern on the surface of the object in order for the infrared camera to sense it. Other equipment such as vibration analysis, oil analysis, and ultrasound can be employed to further determine where the problem actually lies.

Some of the applications and the benefits derived from finding these with thermography may be seen on the next page.

Application Conditions Detected

Electrical / Computer Panels Distribution boards, switchgear, cabling, loose connections, overloads.
Drives/Conveyors, Pillow Blocks, Couplings, Gears, Power Transmission Belts, Pulleys, Shafts. Overheated bearings or rollers, misalignment of shaft, pulley or coupling, lubrication failure uneven pressure.
Motors Overheating of windings and bearings, blockages in cooling passages, friction, damping, material deformations, brush contact problems, rotors
Pumps/Compressors/Fans/Blowers Overheated bearings, high compressor discharges temperature, high oil temperature, and broken or defective valve.
Internal Combustion Engines Valve or injector malfunction, blocked radiator tubes and oil coolers. Thermal distribution, high radiator inlet or outlet temperature.
Heavy Duty Equipment - Tires, Bearings, Brakes, Hydraulics, Kilns, Ball Mills, Paper Machines Overheating brakes, tires, bearings, pulleys, gears, gear or pulley misalignment, and blockages in hydraulics.
Mechanical Drive Turbines and Small Turbine Generator Units, Gas Turbine, Exhaust Ducts High lube oil temperature, high bearing temperatures, faulty stop/control valve operation, uneven metal temperature, leaking shaft seals, gas turbine firing conditions, including deterioration in firing chambers, cross firing tubes.
Ovens, Furnaces, Kilns, Pipes Location and severity of damaged insulation, location of steam leaks in buried steam lines.
Valves: Shutoff Valves, Relief Valves, Steam Traps Leakage, blockage.
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