(a) This Standard covers manually operated thermoplastic valves in nominal valve sizes ½ through 12. These valves are intended for use below ground in thermoplastic fuel gas distribution mains and service lines. The maximum operating pressure (MOP) at which such distribution piping systems may be operated is in accordance with Transportation of Natural and Other Gas by Pipeline; Minimum Safety Standards [49 C.F.R., §192 (2017)] for temperature ranges of –20°F to 140°F (–29°C to 60°C). (b) This Standard sets qualification requirements for each basic valve design as a necessary condition for demonstrating conformance to this Standard. (c) This Standard sets requirements for newly manufactured valves for use in below-ground piping systems for fuel gas [includes synthetic natural gas (SNG)] and liquefied petroleum (LP) gases (distributed as a vapor, with or without the admixture of air) or mixtures thereof.