Butterfly Valve

The butterfly valves provided by Weldon mainly include centric butterfly valve, double offset, triple offset, Lug type, Wafer type, Flanged ended butterfly valve etc. 

The butterfly valve is similar to ball valve, also called quarter-turn valves. It is fully open or closed when the disc is rotated a quarter turn. Butterfly valve is widely used in the pharmaceutical, chemical, and food industries due to lower cost and ease of installation.

Product Range: 
Size: 2 - 120 Inch (DN50 - DN3000).
Pressure Rating: Class 150 - 600 LB (PN16 - PN100).
Material: Cast iron, Carbon steel, Stainless steel, Alloy steel, including WCB, GS-C25, LCB, LCC, LC1, LC3, CF8, CF8M, CF3, CF3M, WC6, C5, C9, C12, 4A, 5A, MONEL, ALLOY20, C95800.
Connection End: Wafer, Lug, Flanged.
Design & Manufacture Standard: API 609.
Test Standard: API 598.
 

The centric butterfly valves have the structural features: the valve stem axis, the center of the disc, and the center of the body at the same position. They are simply structured but convenient for manufacturing. But centric butterfly valves are not suitable for industries with high temperature resistance, high pressure, corrosion resistance and wear resistance.

The structural feature of double offset butterfly valves: the stem axis is offset from the center of the disc and the center of the body. The double eccentric feature of double offset butterfly valves affects the disc to be quickly disengaged from the valve seat after the valve is opened, which greatly eliminates unnecessary over-squeezing and scraping of the disc and the valve seat, reduces the opening resistance, wear and improves the seat life. The scraping is greatly reduced, and the double eccentric butterfly valves can also be used with a metal valve seat, which enhances the application of the butterfly valves in the high temperature field.

The structural feature of triple offset butterfly valves: the conical axis of the disc is skewed to the axis of the body cylinder. The sealing section of the disc is no longer a true circle, but an ellipse. The sealing surface of triple offset butterfly valves is asymmetrical in shape, with one side inclined to the center line of the body and the other side parallel to the center line of the body.
The three eccentricity changes the sealing structure, which relys not on the elastic deformation of the valve seat, but on the contact surface pressure of the valve seat to achieve the sealing effect, avoid the problem of zero leakage and high temperature resistance of the metal valve seat, and it is widely used in power stations, chemical plants, steel mills, etc.