Metallized Carbon Corporation, a manufacturer of oil-free, self-lubricating, carbon-graphite materials for severe service applications, recently announced the availability of bearings specially designed for louver dampers in boiler applications, such as those in coal- or refuse-fired power plants.

The Metcar bearings are used for boiler damper blade shaft bearing applications because of their ability to cope with the high temperatures of these applications. At these high temperatures, oil/grease lubricated bearings are problematic because the lubricants can melt, volatilize or carbonize, causing bearings to gaul and seize and therefore rendering the dampers useless.

Because Metcar carbon-graphite bearings rely on graphite for their self-lubricating properties, they are not subject to the shortcomings associated with petroleum-based lubricants at elevated temperatures. They are stable, not subject to deformation, and can be relied upon to provide low friction damper blade movement even after being stationary for many months. The resiliency and low maintenance of the bearings leads to reduced costs and decreased down time.

Metcar bearings are ideal for use in louver dampers for controlling combustion air input to power generation boilers, given the extremely high temperatures. They are also a great choice for other damper applications, such as in dampers that provide fresh in air underground transportation systems, given that the restricted access to these dampers  makes routine maintenance on oil/grease lubricated bearings too difficult. Metcar self-lubricating carbon-graphite bushings are also used as stem bearings on high temperature butterfly valves, high temperature ball valves and high temperature wafer style dampers.

Standard pillow blocks and flange blocks with Metcar bearing inserts are available with cast iron, stamped steel, or stamped stainless steel housings. Standard flange block bearings are available in English and metric sizes for shafts up to 5” (127mm) in diameter and standard pillow blocks will accommodate shafts to 3” (75mm) in diameter.