Gate valves are generally used as block valves i.e. either fully open or fully closed. Operation is by lifting / lowering the gate between the two seats, by turning a manual hand wheel or other actuating device attached to the stem. The turning of the handwheel causes either the stem to rise pulling up the gate, or the gate to screw up the thread of the stem, hence the definition, rising stem or rising gate. The seat to seal interface in a gate valve is created by the gate pushing down between 2 seats – either machined from the body, swaged or inserted in to the main body of the valve. Energisation of the seat in a wedge gate valve is purely by mechanical force exerted through the stem, by turning the hand wheel. In parallel slide gate valves, energisation of the seat can be by springs between a split gate. Process pressure can also assist in providing a downstream seal in gate valves.
Specifications
General design criteria
Standard pressure class ratings / end connections
Common materials of construction
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Material specifications
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Standard carbon steel
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ASTM A105A216 WCB WCC
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Low temperature carbon steel
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ASTM LF2 A352 LCC LCB
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Stainless steel
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ASTM A182 F316 ASTM A182 F316L ASTM A182 F304 ASTM A182 F304L ASTM A182 F321 ASTM A182 F347 ASTM A351 CF8M ASTM A351 CF3M
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Specials
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F44 SMO F51 Duplex Super Duplex Monel Hastelloy TitaniumInconel Bronze Alu. Bronze
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Other
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Actuated
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