Mechanical Systems

In all plants there are diverse collections of equipment that can be successfully inspected using infrared thermography. For most mechanical equipment the techniques used to inspect the equipment are straightforward, but specific knowledge and experience with some equipment is often required.

You should know the basic operation and heat flow characteristics of the machinery, understand heat related failure mechanisms, have safety inspection procedures and observe the machinery during startup and cool down as well as during normal operation. No one knows the equipment in a plant better than the plant personnel themselves do. It is very helpful to have past experience with the equipment and thermal images of the equipment during normal operations.

We have a few examples of thermography for mechanical systems. The first two thermograms, P) and Q) below show electric motors at 30C (54F) and 40C (72F) above ambient, respectively. Thermogram R) shows a motor coil under test. The camera operator is looking for shorts, which will show up as temperature anomalies. Thermogram S) is a coupling for a high horse power motor and is 6C (10F) below the motor bearing temperature and 12C (20F) below the machine bearing temperature. It is well within its normal operating temperature.

P) Electric motor
Q) Electric motor
R) Coil test
S) Coupler

Thermogram T) is an oil field natural gas compressor where the cylinder head in the lower left of the picture shows signs of a valve problem. Not counting the bolt head parts of the images, this cylinder head shows a 25C (45F) temperature gradient. This gradient was felt to be excessive and it resulted in a tear down and servicing of the compressor. Thermogram U) is an image of a rotating one-foot diameter 3 feet long pinion gear that drives a 50-foot diameter drum in a molybdenum mining operation. By monitoring the lengthwise temperature gradient, the technician could monitor the gear alignment and its life expectancy. Thermograms V) and W) are images of pipe with band heaters. V) shows the heaters on and functioning and W) shows them not working.

T) Compressor
U) Pinion gear
V) Band heater
W) Band heater