Appropriate connections between valves and pipes have direct influence on possibility of valves leakage.
Connections in common use include flanged connection, wafer connection, butt welding connection, threaded connection, sleeve connection, hoop connection, self-sealing connection, etc.
Flanged connection
Two ends of body have a flange which corresponding to flanges on pipe. The
valves are installed on pipe by using bolted flanges. Flanged connection is the mostly used for connecting valves. Flanges can be classified into raised face (RF), flat face (FF), male and female face (MF).
Based on the shape of joint surface, flanged connection can be also classified into following types:
1. Smooth type: used for valves having low pressure; easy for processing;
2. Concave -convex type: having high pressure; medium hard gasket can be used;
3. Mortise type: gasket having high plastic deformation; it is wide used for corrosive media, having good sealing;
4. Dovetail groove type: use oval metal ring as gasket; it is used for valves whose pressure higher 64 kilogram per square kilometer or high temperature valves;
5. Lens type: gasket made of metal is processed into lens type; it is used for valves whose pressure higher 100 kilogram per square meter or high temperature valves;
6. O ring type: it is new type of flanged connection, which develops with rubber O ring; it has more reliable sealing than common flat gaskets.
Wafer connection
Valves are installed between two flanges. Body generally has location holes for installation and location. It is a method that crosses and mingles directly valves and pipes with bolts.
Welded connection
1. Butt welding connection: Two ends of body are processed into butt welding groove as the requirement of butt welding. Ends correspond to butt welding groove of pipe and valves are fixed to pipe by being welded.
2. Socket welding connection: Two end of body are processed as requirements of socket welding. The valves are connected with pipe through socket welding.
