API 594:2004 pdf download

API 594:2004 pdf download.Check Valves: Flanged, Lug, Wafer and Butt-welding.
The total cross-sectional area o the bolts shall be in accordance with the requirements of ASMIi 1116.34.
4.1.16 When valve design utilizes a stem that estends beyond the pressure boundary. it shall be provided with a means so that, in the event of a sinictural failure of stem-to- closure attachment items, (he stern will not be ejected (hrough the pressure boundary while the valve is under pressure.
4.2 PLATES AND DISC
Valves are classified as follows:
a. A single-plate valve has a plate or disc that closes the valve when flow reversal or gravity forces the plate or disc against the valve-body scat. This closure may be aided by the use of springs or other devices.
h. A dual-plate valvc ha.s plates that close the valve with the assistance of one or more spnngs. when flow reversal forces the plates against the valve-body scat.
c. For Type ‘A’ single-plate valves and Type 13 valves, when a nut is used to assemble the disc or plate to the hinge arm, the nut shall be secured to prevent separation: the use of a single tack weld, lock washer or lock nut are not acceptable means.
4.3 SEATING SURFACES
4,3.1 The body and plate or disc seating surfaces may be of deposited weld nwtal, integral metal, mechanically retained metal, or a resilient material. On Type A single-plate valves and Type ‘B’ valves, a resilient seal ring may be fitted either to the body or plate seat as specified by the purchaser. The ring shall be designed to give a full metal to metal seal if the resilient seal is inoperative or removed.
4.3.2 Welding is not perniitied on cast iron or ductile iron.
4.3.3 Brazing is permitted on cast iron and ductile iron only for attaching seating surfaces to the body or the plate and only ii’ agreed to by the purchaser and the manufacturer. Furnace brazing is the only type of brazing permitted and may be used only if the parts are heated under closely controlled conditions. in a uniform manner, and to a temperature no higher than the lower critical temperature of the base material. Cooling shall be in the furnace or in still air.
4.4 EXTERNAL BOLTS AND THREADED HOLES
4.4.1 Bolts and threaded holes with a diameter I in. or
smaller shall have coarse (UNC) threads. Those larger than
I in. diameter shall be of the eight-thread series (8 UN).
Bolt threads shall be Class 2A. and nut threads shall be
Class 2B. Threads shall conform toASME B 1.1.
4.4.2 For bolts I in. diameter or smaller, threaded bodyflange bolt holes shall be drilled and tapped according to the requirenlents for coarse thread series Class 2B
8.2 VALVE OPENINGS
8.2.1 Except for the ends of small, individually packaged valves, valve ends shall be covered to protect the gasket surfaces and valve internals during shipment and storage. The protective covers shall be wood, wood tiber. plastic, or metal and securely attached to the valve ends by bolts, steel straps. or suitable friction locking devices. 11w covers shall be no smaller than the outside diameter of the valve ends and designed so that the valves cannot be installed without complete removal of the covers.
8.2.2 All threaded connections in the valve body shall be fitted with solid, fully tightened plugs conforming to ASMF. Bl6.ll, or ASME 1116.14. Gray iron or malleable iron plugs shall only be used on gray iron or ductile iron valves respectively.
8.3 PACKAGING
8.3.1 When export packaging is not specified in the purchase order. valvcs may be shipped loose. pallctized. or packed in a box or crate. Valves shall be packaged to prevent damage during shipment.
8.3.2 When the purchase order specifies export packaging. valves shall be shipped in wooden boxes or crates. individually or collectively, and packed to prevent their shifting within the package. (The shipping agent representing the purchaser will normally provide detailed instrnctions)