DEVELOPMENT OF GLAND PACKING USING GRAPHITE PELLETS

Recently, the demand for expanded natural graphite is increasing as a material for the gland packing of valves in various industrial fields in place of asbestos. This is in response to the needs for longer serv ice life, higher reliability and lower maintenance, as well as restric tions against the use of asbestos. The expanded natural graphite gland packing has the advantages of far less retightening works and a longe r service life due to its superior features of sealing and heat resist ance. However, there are disadvantages in that the mechanical strength is lower and frictional resistance in movement of the valve stem is h igher. To overcome these drawbacks, we have developed a gland packing using graphite pellets of 3 - 6 mm in diameter made by coating natural graphite with inorganic binder on ceramic core balls of 1 - 2 mm in d iameter based on a new concept.