National standard welding check valve
I. Introduction:
Welding check valves can be driven without a driver, connected by flanges or welding, structured as lift type or swing type, sealed with soft seal or hard seal, with a pressure range of PN0.1-32Mpa, nominal diameter of DN15-600mm, and materials available as cast iron, cast steel, and stainless steel.
II. Working Principle of Welding Check Valve:
A check valve is a valve that automatically prevents fluid backflow. The disc of the check valve opens under the action of fluid pressure, and the fluid flows from the inlet side to the outlet side. When the pressure on the inlet side is lower than that on the outlet side, the disc automatically closes under the action of fluid pressure difference and its own gravity to prevent fluid backflow.
III. Structural Features of Welding Check Valve:
Welding check valves are generally divided into several types such as lift type and swing type.
The structure of a lift check valve is generally similar to that of a globe valve. Its disc moves up and down along the center line of the channel, with reliable operation, but high fluid resistance, suitable for small-diameter applications. Lift check valves can be divided into two types: straight-through type and vertical type. Straight-through lift check valves can generally only be installed on horizontal pipelines, while vertical lift check valves should generally be installed on vertical pipelines.
The disc of a swing check valve rotates around a shaft. Its fluid resistance is generally lower than that of a lift check valve, making it suitable for large-diameter applications. Swing check valves can be divided into three types according to the number of discs: single-disc swing check valve, double-disc swing check valve, and multi-disc swing check valve. The single-disc swing check valve is generally suitable for medium-diameter applications. When a single-disc swing check valve is used for large-diameter pipelines, to reduce water hammer pressure, a slow-closing check valve that can reduce water hammer pressure is preferred. The double-disc swing check valve is suitable for medium and large-diameter pipelines. The lug-type double-disc swing check valve has a small structure and light weight, making it a rapidly developing type of check valve; the multi-disc swing check valve is suitable for large-diameter pipelines.
IV. Materials and Performance Specifications of Main Parts of Welding Check Valve:
Main Components | Valve body, valve cover, rocker arm | WCB | CF8 | CF8M | WC6, WC9 |
Disc | WCB clad with Cr13 or hard alloy | CF8 clad with hard alloy | CF8M clad with hard alloy | WC6, WC9 clad with hard alloy | |
Seat | 25 clad with Cr13 or hard alloy | 304 clad with hard alloy | 316 clad with hard alloy | 20Cr1MoV clad with hard alloy | |
Gasket | Soft iron, XB450 | Polytetrafluoroethylene | Polytetrafluoroethylene | Stainless steel + acid-resistant asbestos wound gasket | |
Bolt | 35CrMoA | 35CrMoA | 35CrMoA | 25Cr1Mo1V | |
Nut | 45 | 45 | 45 | 35CrMoA | |
Main Parameters | Applicable Medium | Oil, water, steam | Nitric acid | Acetic acid | Oil, water, steam |
Applicable Temperature (℃) | ≤425 | ≤200 | ≤200 | ≤550 |
| Machinery & Equipment/Valves/Check Valves | |
