Thermal Imaging has evolved into a valuable diagnostic tool for predictive maintenance. By detecting anomalies often invisible to the naked eye, thermography allows corrective actions to be taken before electrical, mechanical, or process equipment fails. The advent of palm computers and database software has improved and speeded up data collection.
An infrared inspection program can provide users with a quick return on investment. “From our infrared inspection experience we will usually find one item that will pay for the inspection several times over and customers have advised that we save them a minimum of $20,000 per day.” Noted a sales engineer for Indigo Systems in Goleta, California.
According to Scott Cawlfield, president of Logos Computer Solutions, Inc., Seattle Washington, (Infrared Inspection Methods and Data Collection Techniques.”), on average, for every $1 spent on an infrared electrical inspection there is a $4 return on investment for materials and labor to fix the problem equipment before it failed. Depending on other factors, he suggested, that ratio would be closer to 1:20.
The essential elements in an IR inspection program, Cawlfield said are:
- Use or create an equipment inventory list to account for what equipment was tested and when
- Assign a criticality factor to each piece of equipment to prioritize inspection schedules and repairs
- Determine the pertinent information to be recorded in addition to temperature readings and reference points; other factors such as camera emissivity value, equipment load, wind speed, environment, and manufacturer influence temperature readings
- Provide consistent data collection procedures Analyze problem areas and generate appropriate reports.
INSPECTIONS CAN DETECT PROBLEMS AND AVOID COSTLY EQUIPMENT FAILURE
An infrared thermography inspection program has the potential to save an organization considerable money as well optimize equipment operation.
While performing a self-assessment of its infrared thermography program, one company discovered a high temperature on a generator step-up transformer. One of six low voltage bushing enclosures was found to be much hotter than the other five, with peak housing temperatures approximately 250 F as compared to 110F for the other enclosures. An infrared inspection through a 3/8 inch bolt hole identified temperatures in excess of 540F. The plant immediately commenced shutdown.
Subsequent inspection of the transformer/bus connection revealed significant overheating damage to the 25-kV connection, as well as melted aluminum, copper, and even a 304 stainless steel bolt. Root cause analysis concluded that a complete connection failure would have occurred within 2 weeks. The cost benefit analysis for this infrared discovery, using EPRI cost avoidance model and industry experience is estimated to have saved more than $32 million.
One company saved more than $5 million in one year with an infrared program. This savings dropped to only $1 million in a few years. The individual was asked why his performance had dropped and how he could get back to the $5 million level. His answer was to stop doing infrared inspections for about 2 years.
A semiconductor manufacturer saved $275,000 a year when it discovered a heated purified water line was connected directly to a drain.
A major steel company discovered a significant temperature rise in one of its 69 kV breakers. If the problem had gone undetected it could have cost the company $50,000 an hour in lost time due to shutdown.
TRAINING IS IMPORTANT
In-house personnel should understand infrared and heat transfer theory and emissivity, proper selection and operation of equipment, the applications and limitations of thermography, current standards, and proper documentation of findings.
Among the vehicles for gaining the necessary education are attending seminars and training courses, browsing the Internet, studying literature from vendors, and learning from an experienced thermographer during a field inspection.
ARTICLE FROM: “ADVANCED MAINTENANCE TECHNOLOGIES” MAY 2003
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