| 摘要 |
PROBLEM TO BE SOLVED: To minimize damage of a valve seat by using carbon material for a valve element removably provided in a ball valve, and using metal material for the valve seat. SOLUTION: A valve element 3 is removably provided in this ball valve, and the valve element 3 uses carbon fine powder material obtained by adding coal pich or the other organic bider as a binder to single or mixed fine powder with a grain diameter of 149μm or smaller such as petroleum pich coke, carbon black, natural graphite and the like, kneading the same by a mixer, and again grinding the same by a grinder. Metal material such as an aluminum alloy, a copper alloy, a nickel alloy and the like is used for a valve seat 4. Thus, the valve seat 4 is kept from being damaged, and even if damaged, it can be held down to the minimum.
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