Welded check valve has three varieties of valve bonnet designs. The first kind is bolt bonnet, which adopts fillet and groove joint and uses gasket with the material of stainless steel and flexible graphite. It can also adopts ring type joint as required. The second kind is welded bonnet,. It is welded after screw thread sealing. It can also adopt rigid welding as required. The third kind is self-sealing bonnet which connects by thread and pressure seal bonnet.

 

Introduction 

Welded check valve open or close the disc by medium to avoid refluence of medium. It is also called as cut-off valve, one-way valve, reflux valve and back pressure valve.. Welded check valve can be classified into swing check valve (rotating with barycenter) and lift check valve (moving along with axis).

 

Manufacturing Specifications

Manufacturing: MSS SP-118,BS5352,ANSI/ASME B16.34

Test & Inspection: API 598

Marking: MSS SP-25

 

Structure 

1. Full bore or reduced bore;

2. Lift check valve;

3. Ball check valve;

4. Swing check valve;

5. Using spring to assist reset;

6. Bolt bonnet, welded bonnet and self-sealing bonnet

7. Socket Welding: ANSI/ASME B16.11 8;

8. Thread(NPT): ANSI/ASME B1.20.1.