Oxidation Inhibited Graphite: What Is It? Available to Purchase

When exposed to air at elevated temperatures, graphite oxidizes by a reaction between carbon and oxygen forming carbon monoxide and carbon dioxide. Using graphite as a sealing material and exposing it to the aforementioned environment, the reaction consumes graphite which degrades the sealing performance leading to leakage and seal unreliability. As a response to industry needs, graphite and sealing element manufacturers offer “oxidation inhibited” or more simply “inhibited” grades of graphite that show improved resistance to oxidation, however, there is no industry accepted definition that assures the purchaser that these grades of graphite do in fact have sufficient oxidation resistance for their specific application. This paper proposes a performance based definition for oxidation inhibited graphite and a protocol to convert test results to index any graphite resistance to oxidation. Furthermore, the paper provides a methodology to determine temperature limits and/or service life expectations for any graphite grade.