MIL-V-24509, MILITARY SPECIFICATION: VALVES, FLANGED, BALL AND PLUG FOR SEWAGE AND SEA WATER SERVICE (21 OCT 1974)., This specification covers flanged ball and plug valves for sewage and seawater service, under pressure or vacuum. Sewage contains seawater with varying amounts of detergents, caustic, acids, human wastes, sediments, oils, greases, solvents, and other chemical agents used on board ship.