BS EN 593-2004 pdf download.Industrial valves Metallic butterflY valves.
Lugged or single flange wafer valves (see Figure 3) are supplied with threaded or through holes for installation between two flanged components or at the end of a pipeline (i.e end of line service or downstream dismantling).
Threaded holes shall allow full thread engagement to a depth at least equal to the nominal bolt diameter and at least 0.67 of the boll diameter when the bolt hole is adjacent to the valve shaft
For Class designed valves threaded body flange holes for bolts 1 inch or less in diameter shah be drilled and tapped in accordance with ASME Bi 1, UNC coarse thread series, Class 2B. For bolts 1118 inches or nlcwe in diameter, such holes shall be drilled and tapped in accordance with ASME 811, UN 8 eight thread series, Class 28. Threads according to other standards shall be specified.
The manufacturer’s literature shall be consulted to determine if through bolting or1and end of brie assembly is possible Any limitation regarding end of line service condition shall be indicated,
Elastomneric or plastic linings and liners can be extended over the flange faces of the body to form a gasket for the flange
4.1.1.3 Obturator (disc)
The valve manufacturer’s technical documentation shall specify all necessary dimensions showing the
protrusion of the obturator in the open position bend the faces of the valve
4.1.1.4 Seat seal or body liner
The valve manufacturer’s technical documentahon shall specify whether the seal seal or body liner is replaceable or non-replaceable
4.1.1.5 Driving shaft
The external end of the driving shaft shall indicate the orientation of the obturator
The shaft shall indicate by design or marking the position of the obturator Where requwed by the design of valve, the manufacturer’s operating instructions shall specify the method to preserve the indication of the obturator position, during and after re-assembly of the obturator to the shaft, e g for routine maintenance.
The sealing of the shaft shaH remain leak tight to atmosphere when the operating device is removed
The shaft shall be retained in the valve, so it cannot be ejected out of the body when external parts are removed
When anti-blow out design is required, it shall be in accordance with EN 736-3
External parts as stated in 3.3 7 of EN 736-3 1999, are parts which are not included in the bare shaft valve
e g Ixacket. lever, actuator
4.1.1.6 Other requirements
a) Body and cover the steel alloy materials fo the body and cover (if any) shall be selected from the grades hsted in prEN 12516-1
NOTE For metaIl materals other than steel, the body and cover (if any) materials should be se’ected from the grades Isted in prf N 12516-4
b) Bolting bolting material shall be selected from EN 10269.
4.1.2.2 Trim
The trim comprises the following
a) obturator
b) shaft(s)
c) seat or liner
The valve manufacturer’s technical documentation shall specify the relevant materials for the trim parts (see annex B)
The materials of seat and liner can be elastomeric, plastic. composite. metallic or a combination of these materials
The valve manufacturer’s technical documentation shall specify the material type of the seat or liner
4.1.2.3 Corrosion protection
a) External corrosion protection valve shells shall be protected against corrosion by proper material selection or surface treatment
The valve manufacturer’s technical documentation shall specify the choice of the materials andlor the type of the surface treatment
Surface treatment system may be chosen according to classification category given by annex C. Test assessment and test procedures are the responsibility of the manufacturer
b) Internal corrosion protection all surfaces in contact with the fluid shall be protected against corrosion by suitable material selection or surface treatment (see annex fl)
The valve manufacturer’s technical documentation shall specify the materials and for the type of surface treatment
4.1.3 Pressure/temperature ratings
The pressure/temperature rating shall be as specified in:BS EN 593-2004 pdf download.