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Application Notes:
Inspecting Furnaces and Boilers |
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Furnaces and boilers play important roles in many industries as well as in the heating of commercial and institutional buildings. They heat products in petroleum, chemical and pharmaceutical industries and produce or handle molten products in glass, steel and other industries. In most cases, if only because of their high operating temperatures and their capacity to cause injury or death as a result of some failures, furnaces and boilers should be included in predictive maintenance (PdM) programs that monitor their condition while they operate. |
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The purpose of a PdM program is to detect and prevent imminent failures before they occur to avoid the shutdown of critical equipment. One especially powerful tool for monitoring the condition of furnaces and boilers is thermal imaging, which captures two-dimensional images of the temperature profiles of objects. Thermal images can reveal potential points of failure in furnaces and boilers and help extend the life of their refractory insulation.
What to check?Use a thermal imager to check any critical furnace, process heater or boiler, prioritizing those whose failure could threaten human health or safety, property, productivity or the product itself.
Highly skilled thermographers report some success checking the tubes of furnaces and boilers for hot spots, which can signal a potential failure.
What to look for?To protect personnel and property, furnaces, boilers, process heaters and other heat-generating units have insulation or refractory lining their external walls. Using a thermal imager, technicians can look for hot spots on the walls. The hot spots will reveal where the refractory is less effective.
What represents a "red alert"?Equipment conditions that pose a safety risk should always receive the highest repair priority. Clearly, one of the most potentially dangerous situations that might occur is the failure of a furnace or ladle for a molten material such as glass or steel.
What's the potential cost of failure?A catastrophic failure in the glass or steel industry would constitute a multi-million dollar production stoppage, even if there were no injuries or deaths. Cold glass cannot be reheated. And how does one recover solidified, once molten iron or steel?
Follow-up actionsWhen you discover a problem using a thermal imager, use the associated software to document your findings in a report that includes a thermal image and a digital, image of the equipment. It's the best way to communicate the problems you found and any suggested repairs.
In general, if a catastrophic failure appears imminent, the equipment must either be removed from service or repaired while operating. In the steel industry, both strategies are employed. When it comes to ladles for molten product, mills generally have enough ladles to take a failing one out of service for repairs and replace it with a sound one.
In either case, following repairs, new thermal images can be used to assess the effectiveness of repairs and evaluate the repair materials used. With this information, you can continuously...
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