Stem nut in the process of opening and closing the valve, the valve stem directly bear axial force, it must have a certain strength. Also it is a screw drive with the stem, requiring low friction coefficient, does not rust and prevent galling.

First, the copper alloy copper alloy friction coefficient is small, does not rust, is one of the materials commonly used. For Pg <1.6Mpa low-pressure valve can be ZHMn58-2-2 cast brass. For Pg16-6.4Mpa medium pressure valve can be ZQAL9-4 Wuxi bronze. For high pressure valves can be ZHAL66-6-3-2 cast brass.

Second, when the working conditions do not allow steel with copper alloy, the choice of 35, 40 and other high-quality carbon steel, 2Cr13, 1Cr18Ni9, Cr17Ni2 other acid-resistant stainless steel. Working conditions were not refer to the following.

① For electric valve, with melon-shaped clutch stem nut, the need for heat treatment to obtain high hardness or table

Surface hardness.

② The working medium or the surrounding environment is not suitable for use copper alloys, such as copper corrosion ammonia media. Use the steel stem nut, pay special attention to thread galling.

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