Standard Practice (SP)-136 was originally published in 2007 and continues to serve the industry by providing requirements for ductile iron swing check valves with flanged, threaded, mechanical-joint, push-on, grooved, and shoulder ends for general purpose usage. This Standard Practice covers check valves for installation in pipelines that are horizontal or in pipelines where flow is above horizontal, up to vertical, with flow upward. SP-136 continues to be maintained under the consensus of MSS Technical Committee 106, Cast Iron Valves.