This 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 Tables 2A and 2B 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 Class 125 and 250 cast iron flanges as specified in ASME B16.1@ between Class 150 and 300 ductile iron flanges as specified in ASME B16.42@ between Class 150 - 2500 steel flanges as specified in ASME B16.5@ and between Class 150 - 600 steel pipeline flanges as specified in MSS SP-44 or carbon steel flanges as specified in ASME B16.47. Type `B' check valves are long face-to-face as defined in 4.1.2 and can be: flanged or butt-welding; steel@ nickel alloy or other alloy designed for installation between Class 150 - 2500 steel flanges as specified in ASME B16.5 or for butt-welding into industry accepted piping systems.