API STD 594:2010 pdf free download.Check Valves: Flanged, Lug, Wafer, and Butt-welding
5.1.3.1 Welding a flange to a valve body shall be by full penetration butt-welding. The welding procedure and the welder or welding operator shall be qualified in accordance with ASME-BPVC, Section IX. Valves having flanges attached by welding shall meet the requirements of paragraph 2.1.6 of ASME B16.34.
5.1.3.2 Integral or other alignment rings (centering backing rings) used to facilitate welding shall be completely removed after the weld is completed.
5.1.4 Type ‘A’ valves larger than DN 600 (NPS 24) in Classes 150, 300, and 600 shall have body-flange bolt patterns suitable for the lug or double-flanged type, outside diameters suitable for the wafer type, and gasket surface dimensions compatible with the flange standards specified in the purchase order.
5.1.5 Flange faces with ring-joint grooves shall conform to the dimensions shown in either ASME B16.5 or ASME B16.47, as applicable. 5.1.6 Flange facing finishes shall be:
— Type ‘A’ valves only: gray iron and ductile iron valves shall be finished as specified in MSS SP-6;
— Type ‘A’ and Type ‘B’ valves: steel, nickel-alloy, and other alloy valves shall be finished as specified in ASME B16.5.
5.1.7 Auxiliary connections are required only when specified by the purchaser:
— Type ‘A’ valves only: For gray iron and ductile iron valves the size, type, and location of auxiliary connections shall be the manufacturer’s standard unless otherwise agreed by the manufacturer and the purchaser.
— Type ‘A’ and Type ‘B’ valves: For steel, nickel alloy and other alloy valves auxiliary connections shall comply with the requirements of ASME B16.34, Section 6.3. The location and designation of auxiliary connections shall be manufacturer’s standard for Type ‘A’ valves and per ASME B16.34, Figure 1(b) for Type ‘B’ valves.
5.1.8 The valve may have either an integral or a removable seat ring. Sealing compounds or greases shall not be used when assembling seat rings; however, a light lubricant having a viscosity no greater than kerosene may be used to prevent galling of mating threaded surfaces.
5.1.9 Tapped test openings are permitted only if specified in the purchase order. If a tap is made in the body for testing the valve, the tap shall not be larger than DN 15 (NPS 1 / 2 ). After testing, the tapped hole shall be fitted with an ASME B16.11 or ASME B16.14 threaded solid round or hex-head plug. The test tap may require a boss to provide the minimum thread engagement, as specified in ASME B16.34.
5.1.10 For Type ‘A’ valves a tapped blind hole shall be provided in the body of valves which are either NPS 10 or larger, or which weigh more than 50 lb (23 kg), for attachment of an eye bolt or equivalent lifting device. The hole shall be tapped with a coarse (UNC) Class 2B thread, conforming to ASME B1.1. If an eyebolt is specified in the purchase order, it shall conform to ASME B18.15.
5.1.11 Unless otherwise specified in the purchase order, for Type ‘A’ valves the lugs of lug type valves and flanges of double-flanged type valves shall be provided with non-threaded (drilled) bolt clearance holes.
5.1.12 Butt-welding ends shall conform to the requirements of ASME B16.25 for the bore specified for use without backing rings.
5.1.13 Conversion of a flanged end to a butt-welding end is not permitted except by agreement between the purchaser and manufacturer.
5.1.14 Type ‘B’ valves shall have a bolted cover design that meets the requirements of ASME BPVC, Section VIII, flat covers shall conform to UG 34 and dished covers shall conform to Appendix I-6. Cover and cover flanges shall be circular except DN 50 and DN 65 (NPS 2 and NPS 2 1 / 2 ) may be of non-circular design. Body-to-cover joint shall be flanged with a flat face (Class 150 only), raised face, tongue and groove, spigot and recess, or ring joint per ASME B16.5.API STD 594 pdf download.API STD 594:2010 pdf free download
