MSS SP-88

Abstract

This Standard Practice applies to valves for gen-eral liquid and gas service that effect valve closure by means of a resilient diaphragm sealing against a weir or a diaphragm acting in conjunction with a separate or integral disk-member sealing against a seat, having equal sealing capability in either flow direction, and having diaphragms being essentially made of elastomeric or plastic material or combinations thereof. <br>This Standard Practice defines the following categories of valves: <br>a) Class 125 or 150 Valves; <br>b) Standard Valves; <br>c) Valves for Special (Low Pressure) Applications. <br>The purchaser, when referencing the Standard, shall also specify the appropriate category as listed above. <br>This Standard Practice covers the following: <br>a) Pressure-Temperature Ratings and Design requirements; <br>b) Commonly Used Diaphragm Pressure Limitations; <br>c) Body, Bonnet, and Bolting Materials; <br>d) Commonly Used Face-to-Face Dimensions for Flanged Valves; <br>e) Body End Connections and Wall Thicknesses; <br>f) Actuator Application Requirements; <br>g) Tests; <br>h) Marking.