This standard describes only iron-body unassisted swing-check valves, 2-in. through 48-in. (50-mm through 1,200-mm) NPS, with mechanical-joint or flanged ends that are installed in approximately level settings in water systems.This standard can be referenced in specifications for swing-check valves for waterworks service, where the stipulations of this standard apply when this document has been referenced and then only to swing-check valves for waterworks service, 2-in. through 48-in. (50-mm through 1,200-mm) NPS.