American Petroleum Institute

Check Valves: Flanged, Lug, Wafer, and Butt-welding - Seventh Edition
 N STD 594

Annotation

This international standard covers design, material, face-to-face dimensions, pressure-temperature ratings, and examination, inspection, and test requirements for two types of check valves.

— Type ‘A' check valves are short face-to-face as defined in Table 3 and Table 4 and can be: wafer, lug, or double flanged; single plate or dual plate; gray iron, ductile iron, steel, nickel alloy, or other alloy designed for installation between Classes 125 and 250 cast iron flanges as specified in ASME B16.1, between Classes 150 and 300 ductile iron flanges as specified in ASME B16.42, between Classes 150 and 2500 steel flanges as specified in ASME B16.5, and between Classes 150 and 600 steel pipeline flanges as specified in MSS SP-44 or steel flanges as specified in ASME B16.47.

— Type ‘B' bolted cover swing check valves are long face-to-face as defined in 5.1.2 and can be: flanged or buttwelding ends of steel, nickel alloy, or other alloy material. End flanges shall be as specified in ASME B16.5 or ends shall be butt-welding as specified in ASME B16.25.

This standard covers the following ranges:

— Type ‘A' valves:

a) Classes 125 and 250, 50 ? DN ? 1200 (2 ? NPS ? 48) (excluding DN 90 [NPS 31/2]);

b) Classes 150 and 300, 50 ? DN ? 1200 (2 ? NPS ? 48)*;

c) Class 600, 50 ? DN ? 1050 (2 ? NPS ? 42)*;

d) Classes 900 and 1500, 50 ? DN ? 600 (2 ? NPS ? 24)*;

e) Class 2500, 50 ? DN ? 300 (2 ? NPS ? 12)*;