API STD 609:2004 pdf download.Butterfly Valves: Double Flanged, Lug- and Wafer-Type
1 Scope
1.1 This standard covers design, materials, face-to-face dimensions; pressure-temperature ratings; and examination, inspection, and test requirements for gray iron, ductile iron, bronze, steel, nickel-base alloy, or special alloy butterßy valves that provide tight shutoff in the closed position and are suitable for ßow regulation. Two categories of butterßy valves are included: a. Category A: ManufacturerÕs rated cold working pressure (CWP) butterßy valves, usually with a concentric disc and seat conÞguration. Sizes covered are NPS 2 to NPS 48 for valves having ASME Class 125 or Class 150 ßange bolting patterns. b. Category B: Pressure-temperature rated butterßy valves that have an offset seat and either an eccentric or a concentric disc conÞguration. These valves may have a seat rating less than the body rating. For lug and wafer, Class 150, 300, and 600, sizes covered are NPS 3 to NPS 24 . For double ßanged long pattern, Class 150, 300, and 600, sizes covered are NPS 3 to NPS 36. For double ßanged short pattern, Class 150 and 300, sizes covered are NPS 3 to NPS 48. For double ßanged short pattern, Class 600, sizes covered are NPS 3 to NPS 24.
1.2 Valve conÞgurations include double ßanged, lug- and wafer-types with facings that permit installation between ASME and MSS ßanges that conform to the standards and speciÞcations listed in Section 2.
For valves that are not fully rated, each size and pressure class of threaded-lug or double ßanged butterßy valve, the manufacturer shall perform prototypical tests in both ßow directions to determine the maximum pressure (up to 1.1 times the valveÕs rated differential pressure) that produces a leak rate acceptable per API Standard 598 for each ßow direc- tion (or a single ßow direction for unidirectional valves). For bidirectional dead-end service valves, tests shall be per- formed with the seat retainer side of the prototypical test valve fully unrestrained. For unidirectional dead-end service valves, test shall be performed with the downstream side of the prototypical test valve fully unrestrained. Based on these tests, the manufacturer shall mark each valve stating maximum bidirectional dead-end pressure xxx, where xxx represents 90% of the lowest pressure in either ßow direction determined from the prototypical tests. For unidirectional valves the marking shall be maximum unidi- rectional dead-end pressure xxx, where xxx represents 90% of the lowest pressure in the appropriate direction determined from the prototypical tests. Additionally, the manufacturer will include this information in catalogs and installation, maintenance, and operating documents.