API STD 594 pdf download

API STD 594 pdf download Check Valves: Flanged, Lug, Wafer, and Butt-welding
5.1.3 For Type “A” valves, the purchase order shall specify whether the body type shall be wafer, lug, or doubleflanged; for Type “B” valves, the purchase order shall specify whether the body type shall be flanged or butt-welding.
5.1.3.1 End and cover flanges shall be integrally cast or forged with the body.
5.1.3.2 Flanges may be attached by full penetration butt-welding if agreed to by the purchaser, in which caseflanges shall conform to ASMEB16.5 or ASMEB16.47 and have butt-welding ends for use without backing rings.5.1.3.3 Flanges for iron valves shall only be the integral type.
5.1.3.4 Welding a flange to a valve body shall be by full penetration butt-welding. The welding procedure andthe welder or welding operator shall be qualified in accordance with ASME BPvC, Section lX. Valves that haveflanges attached by welding shall meet the requirements of paragraph 2.1.6 of ASME B16.34.
5.1.3.5 Integral or other alignment rings (centering backing rings) used to facilitate welding shall be completelyremoved 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 boltpatterns suitable for the lug or double-flanged type, outside diameters suitable for the wafer type, and gasketsurface 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 orASME B16.47 Series “A”, as applicable.
5.1.6 Flange-facing finishes shall be:
a) Type”A” valves only: Gray iron and ductile iron valves shall be finished as specified in MSS SP-6.
b)Type “”A” and Type “B” valves:ASME B16.34,Table 1,Group 1,2, or 3 valves shall be finished as specified in ASME B16.5 or ASME B16.47 Series “A”, as applicable.
5.1.7 Auxiliary connections are required only when specified by the purchaser:
a) Type “A” 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.
b)Type”A”ASMEB16.34,Table 1, Group 1,2,or 3 valves:Auxiliary connections shall conform to therequirements of ASMEB16.34.The location and designation of auxiliary connections shall be the manufacturer’s standard.
c) Type “B” valves: For ASME B16.34,Table 1,Group 1, 2, or 3 valves, auxiliary connections shall conform to the requirements of ASME B16.34.The location and designation of auxiliary connections shall be perASMEB16.34.
5.1.8 The valve may have either an integral or a removable seat ring.Sealing compounds or greases shall notbe used when assembling seat rings; however, a light lubricant that has a viscosily no greater than kerosene maybe used to prevent galling of mating threaded surfaces.Separate seats shall be secured against loosening.
5.1.9Tapped test openings are permitted only if specified in the purchase order. The tap shall not be larger thanDN 15(NPS 1,) if a tap is made in the body for testing the valve.After testing, the tapped hole shall be ftted withan ASME B16.11 or ASMEB16.14 threaded solid round or hex-head plug.The test tap shall conform with ASMEB16.34.
5.1.10 For Type “A” and Type “B” valves, a tapped blind hole shall be provided in the body, cover,or cap ofvalves that are either DN 250 (NPs 10) or larger, or weigh more than 23 kg (50 lb), for attachment of an eye boltor equivalent lifting device. The hole shall be tapped with a coarse (UNC) class 2B thread, conforming to ASMEB1.1 class 2B (U.S. customary) or ASME B1.13M class 6g (metric). Eyebolts specified in the purchase ordershall conform to ASME B18.15(U.S. customary) or either ISO 3266 or DIN 580(metric).
5.1.11 Unless otherwise specified in the purchase order, for Type “A” valves, the lugs of lug-type valves andflanges of double-flanged type valves shall be provided with non-threaded (drilled) bolt clearance holes. If themanufacturer determines there is inadequate clearance for holes through the lug due to the proximity of the hingepin or other internal component, tapped blind holes may be supplied at these locations only.Tapped holes in thelugs shall comply with the following:
a) Tapped lug holes for bolts 1 in. or less in diameter shall be drilled and tapped in accordance with ASMEB1.1,
coarse-thread series, class 2B. For bolts 1/, in.or more in diameter, such holes shall be drilled and tappedin accordance with ASME B1.1, eight-thread series, class 2B.
b) Each hole shall be fully tapped, using at least three tapping steps, including taper, plug, and bottoming taps.c)The finished threaded bolt holes shall have full undamaged threads to a depth at least equal to the nominalbolt diameter.
d)The manufacturer shall specify the minimum depth of full undamaged threads.
5.1.12 Type“B” valves shall have a bolted flat or dished cover design that meets the requirements of ASMEBPvC,Section vIlI,Division1.
Gasket contact surfaces shall be free of sealing compounds. A light coating of a lubricant,no heavier thankerosene, may be applied if needed to assist in proper gasket assembly.
5.1.13 lf a valve design utilizes a stem that extends beyond the pressure boundary, stem retention shall bein accordance with ASME B16.34.The design shall not rely on actuation components (e.g., gear operators,actuators, levers, etc.) to prevent ejection.
5.1.14Type “B” swing check valves shall be equipped with a single-contact stop point to prevent the possibilityof the disc getting stuck in the open position.
5.1.15 Type “B” valves: Cover and cover flanges shall be circular, except for DN 50 and DN 65(NPS 2 and NPS21,). which may be of noncircular design.