Basic End Connection Types of Valves

1. Typical drawings of valve end connection types

2. Technical specification of valve end connection types

1) Butt Welded Connections(BW): A butt-weld connection is made by welding the beveled ends of the pipe and straight end of the valve together. Weld along a seam that is butted edge to edge. Beveled ends(BE) indicate that the ends of the pipe lengths of the valve are not cut square, but rather are cut or ground to have a tapered edge. The butt-weld ends in standard valves are machined in accordance with ASME B16.25. Wall thickness should be clearly specified by customers.

2) Socket Welded Connections(SW): For a socket-weld connection valve, the pipe is inserted into the socket of the valve before welding, unlike a butt-weld connection that has the pipe and valve straight end placed end-to-end. Inside the socket-weld end is a collar that prevents the pipe from being inserted too deeply into the valve. Compared with butt-weld connections, socket-weld connections are more cost-effective since they are just simple fillet welds which require less X-ray inspection and less labor work.

3) Screwed Connections(NPT): Screwed connections are typically used in valves sized 4" and smaller. With tapered grooves cut into the ends of a run of pipe, screwed pipes and screwed valve ends can be easily assembled. NPT is the most common thread type tapered in accordance with ASME B1.20.1.

4) According to the flanged ends either formed together or separately with the valve body, there are three flanged connection types of valves: Raised Face(RF), Ring Type Joint(RTJ) and Flat Face(FF). The mating surface of the flanged valve connection is called the face. The face is usually machined to create a smooth surface which will help assure a leak-proof seal when two flanges are bolted together with a gasket sandwiched between.

Views: Author：hbmetals Date:15/06/02