national standard welding check valve
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I. Introduction:
Welded check valves can be driven without a drive mechanism. Their connection methods can be flanged or welded. Their structural forms can be lift type or swing type. Their sealing structures can be soft sealing or hard sealing. The pressure range is PN0.1-32Mpa, the nominal diameter is DN15-600mm, and the available materials are cast iron, cast steel, and stainless steel.
II. Working Principle of Welded Check Valves:
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 combined action of fluid pressure difference and its own gravity to prevent fluid backflow.
III. Structural Features of Welded Check Valves:
Welded 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, ensuring reliable operation. However, it has relatively high fluid resistance and is suitable for applications with small diameters. Lift check valves can be further divided into two types: straight-through type and vertical type. The straight-through lift check valve can generally only be installed on horizontal pipelines, while the vertical lift check valve should generally be installed on vertical pipelines.
The disc of a swing check valve rotates around a rotating shaft. Its fluid resistance is generally lower than that of a lift check valve, making it suitable for applications with larger diameters. According to the number of discs, swing check valves are divided into three types: single-disc swing check valves, double-disc swing check valves, and multi-disc swing check valves. Single-disc swing check valves are generally suitable for medium-diameter applications. When a single-disc swing check valve is selected for large-diameter pipelines, to reduce water hammer pressure, it is best to use a slow-closing check valve that can mitigate water hammer pressure. Double-disc swing check valves are suitable for medium and large-diameter pipelines. The wafer-type double-disc swing check valve has a compact structure and light weight, making it a rapidly developing type of check valve. Multi-disc swing check valves are suitable for large-diameter pipelines.
IV. Materials and Performance Specifications of Main Parts of Welded Check Valves:
Main Parts | Valve body, valve cover, rocker | WCB | CF8 | CF8M | WC6, WC9 |
Disc | WCB hardfaced with Cr13 or cemented carbide | CF8 hardfaced with cemented carbide | CF8M hardfaced with cemented carbide | WC6, WC9 hardfaced with cemented carbide | |
Seat | 25 hardfaced with Cr13 or cemented carbide | 304 hardfaced with cemented carbide | 316 hardfaced with cemented carbide | 20Cr1MoV hardfaced with cemented carbide | |
Gasket | Soft iron, XB450 | Polytetrafluoroethylene (PTFE) | Polytetrafluoroethylene (PTFE) | Stainless steel + acid-resistant asbestos spiral 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 |
| Industry Category | Machinery & Equipment/Valves/Check Valves |
|---|---|
| Product Category | |
| Brand: | 上海舟腾 |
| Spec: | 无 |
| Stock: | 99 |
| Manufacturer: | 上海舟腾泵阀制造有限公司 |
| Origin: | 113120 |
