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Gray Iron Swing Check Valves, Flanged and Threaded Ends

This 2005 edition of MSS SP-71 added minimum wall requirements that were previously omitted. The addition of the minimum wall thickness requirements are necessary to qualify the valves for Class 125 and Class 250 pressure-temperature designation/rating as defined in ASME B16.1 and Table 1 of this MSS Standard Practice. This edition also deleted the PN designations, which were easily confused with designations in international standards that are based on other material specifications and pressure-temperature rating procedures. ISO references were deleted from Annex C.
This Standard Practice covers gray iron swing check valves with flanged and threaded ends for general purpose service. The use of swing check valves in steeply inclined or vertical lines requires special consideration.
This Standard Practice also includes, directly or by reference, stipulations on chemical and mechanical properties of materials and dimensions of end connections in common use.


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October 16, 2021

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