ANSI bellows seal stop valve characteristic: Double-decked corrugated pipe, service convenient, dual seals, position instruction; application situation: The power plant, the natural gas, the ammonia, the vacuum, the freezing systematic, the hot oil system, the hot water. Design manufacture standard: API 602; fac to fac standard: ANSI B16.10; flange standard: ANSI B16.11; examination experiment standard: API 598.