BS EN 593:2004 pdf free.Industrial valves—Metallic butterfly valves.
BS EN 593 Flanges of double flanged valves and single flange wafer valves shall have bolt holes in accordance with therelevant standard as specified in 4.1.4.2.Threaded holes can be provided where the design of the valveprecludes through flange bolting.
Flangeless wafer valves (see Figure 2) are intended for clamping between pipe flanges using through bolting.The shape of wafer valve bodies shall be such that centering of the valves within the appropriate flange bot circle is ensured. Where through bolting is not practicable due to the valve design， e.g.close to shaftpassages, threaded holes can be provided for individual bolting.
Lugged or single flange wafer valves (see Figure 3) are supplied with threaded or through holes for installationbetween two flanged components or at the end of a pipeline (i.e. end of line service or downstreamdismantling).
Threaded holes shall allow full thread engagement to a depth at least equal to the nominal bolt diameter andat least 0,67 of the bolt 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 shall be drilled andtapped in accordance with ASME B1.1,UNC coarse thread series, Class 2B.For botis 1 1/8 inches or more indiameter, such holes shall be drilled and tapped in accordance with ASME B1.1,UN 8 eight thread series,Class 2B.Threads according to other standards shall be specified.
The manufacturer’s literature shall be consulted to determine if through bolting orland end of line assembly ispossible.Any limitation regarding end of line service condition shall be indicated.
Elastomeric or plastic linings and liners can be extended over the flange faces of the body to form a gasket forthe flange.
The valve manufacturers technical documentation shall specify all necessary dimensions showing theprotrusion of the obturator in the open position beyond the faces of the valve.
The valve manufacturer’s technical documentation shall specify whether the seat seal or body liner isreplaceable or non-replaceable.
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 required by the design ofvalve, the manufacturer’s operating instructions shall specify the method to preserve the indication of theobturator position, during and after re-assembly of the obturator to the shaft, e.g. for routine maintenance.BS EN 593 pdf download.