Page 116 - Intro Predictive Maintenance

Predictive Maintenance Techniques 107

short time. Most of the imaging systems function much like a video camera. The user
can view the thermal emission profile of a wide area by simply looking through the
instrument’s optics.

A variety of thermal imaging instruments are on the market, ranging from relatively
inexpensive, black-and-white scanners to full-color, microprocessor-based systems.
Many of the less expensive units are designed strictly as scanners and cannot store
and recall thermal images. This inability to store and recall previous thermal data will
limit a long-term predictive maintenance program.

Point-of-use infrared thermometers are commercially available and relatively inex-
pensive. The typical cost for this type of infrared instrument is less than $1,000.
Infrared imaging systems will have a price range between $8,000 for a black-and-
white scanner without storage capability to over $60,000 for a microprocessor-based,
color imaging system.

Training is critical with any of the imaging systems. The variables that can destroy
the accuracy and repeatability of thermal data must be compensated for each time
infrared data are acquired. In addition, interpretation of infrared data requires exten-
sive training and experience.

Inclusion of thermography into a predictive maintenance program will enable you to
monitor the thermal efficiency of critical process systems that rely on heat transfer or
retention, electrical equipment, and other parameters that will improve both the reli-
ability and efficiency of plant systems. Infrared techniques can be used to detect prob-
lems in a variety of plant systems and equipment, including electrical switchgear,
gearboxes, electrical substations, transmissions, circuit breaker panels, motors, build-
ing envelopes, bearings, steam lines, and process systems that rely on heat retention
or transfer.

6.2.2 Infrared Thermography Safety

Equipment included in an infrared thermography inspection is usually energized;
therefore, a lot of attention must be given to safety. The following are basic rules for
safety while performing an infrared inspection:
• Plant safety rules must be followed at all times.
• A safety person must be used at all times. Because proper use of infrared
imaging systems requires the technician to use a viewfinder, similar to a
video camera, to view the machinery to be scanned, he or she is blind to the
surrounding environment. Therefore, a safety person is required to ensure
safe completion.
• Notify area personnel before entering the area for scanning.
• A qualified electrician from the area should be assigned to open and close
all electrical panels.
• Where safe and possible, all equipment to be scanned will be online and
under normal load with a clear line of sight to the item.