Butterfly Valves are manufactured in accordance with the specifications from ISO 5272, International Standards Organization and MSS SP-67, Manufacturers Standardization Society and API-609, American Petroleum Institute. Latest revisions. Both Lug and Wafer series valves are designed for ANSI 125/150 lb. class flanges. Valve sizes from 2" to 12" are rated at 200 psig WOG service and valve sizes from 14" to 30" are rated at 150 psig WOG service. All valves are full rated on dead-end service.