The primary function of a needle valve is isolation. The secondary function could be throttling (although not recommended as this can result in erosion of the sealing surface) and the third function is reduction, where the seat aperture in the needle valve is a smaller bore than the piping bore.
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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