API 609-2016 standard is a purchase specification for butterfly valves designed for installation between flanges specified in ASME B16.1,ASME B16.5,ASME B16.24,and ASME B16.42,Classes 125-600; MSS SP-44,Class 150; and ASME B16.47,
Series A, Class 150 (was MSS SP-44 except for certain materials) or Series B (was API 605). Class 150 for the NPS sizes defined herein.
