API 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 buttrfly valves that provide tight shutoff in the closed position and are suitable for flow regulation. Two categories of butterfly valves are included: a. Category A: Manufacturer’s rated cold working pressure (CWP) butterfly valves, usually with a concentric disc and seat configuration. Sizes covered are NPS 2 to NPS 48 for valves having ASME Class 125 or Class 150 flange bolting patterns. b. Category B: Pressure-temperature rated butterfly valves that have an offset seat and either an eccentric or a concentric disc configuration. 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 flanged long pattern, Class 150, 300, and 600, sizes covered are NPS 3 to NPS 36. For double flanged short pattern, Class 150 and 300, sizes covered are NPS 3 to NPS 48. For double flanged short pattern, Class 600, sizes covered are NPS 3 to NPS 24. 1.2 Valve configurations include double fanged, lug- and wafer-types with facings that permit installation between ASME and MSS flanges that conform to the standards and specifications listed in Section 2. 2 References The most recent edition or revision of the following stan- dards or specifications shall, to the extent specified in this standard, form a part of this standard. Text in brackets after a publication title indicates a restriction on the classes to which the publication applies.
4.1.4 Disc Position Indication The indication of the position of the disc shall be integral with the valve shaft. The indication may be accomplished by a mark on the shaft or by a shaft shape. The design shall ensure that a valve (and/or operator) cannot be assembled to falsely indicate the valve’s open and closed positions. 4.1.5 Shaft-to-Lever Connections Shaft-to-lever connections shall be designed so that the lever always correctly indicates the disc position. 4.2 BODY 4.2.1 The minimum body-wall thickness shall comply with the applicable ASME B 16 standard listed in Section 2 based on the body material. If the applicable standard covers fttings for a particular material, the valve minimum wall thickness shall be as specified for fttings. The valve design shall be structurally suitable for its stated pressure and temperature limits, taking into account that localized thinning may be nec- essary between the shaft bore in the body and the adjacent bolt holes. Such sections shall be designed in accordance with the requirements of ASME B 16.34. 4.2.2 When a wafer-type valve is installed between piping flanges and the disc is in the closed position, the valve shall be self-centering, that is, designed to center itself within the bolt circle by using the valve’s outside diameter, or by means of integral or atached alignment devices. 4.2.3 End flanges for double flanged valves shall be inte- grally cast or forged with the body; however, flanges may be attached by full- penetration butt welding if agreed to by the purchaser. End flanges attached by welding shall conform to ASME B16.5 and have butt-welding ends for use without backing rings. Welds shall conform to ASME B31 .3, as shall qualifications for the welding procedure and the welder or welding operator. The finished weld thickness shall not be less than the minimum body-wall thickness.