National Standard Threaded Shut-off Valve

1. Basic structure and principle of operation
● Structure: Consists of valve body, valve disc (sealing surface), valve stem, handwheel and threaded interface.

● Working principle: When the handwheel rotates to move the valve stem up and down, the valve disc and valve seat are installed or separated to achieve on-off or fluid flow control.

2. Main Features
● Connection Method: Threaded connection is used, and the common thread standards are G (Pipe Thread) or NPT (American Standard Tapered Thread), which is convenient for installation and disassembly.

● Sealing characteristics: The sealing surface of the valve disc and valve seat usually adopts metal solid seal or soft material (such as PTFE) to ensure a tight closure.

● Flow direction design: Generally, it is low inlet and high outlet (the medium enters under the valve disc), which reduces the working torque and prolongs the service life of the seal.

● Applicable pressure/temperature: According to the material, the applicable pressure is generally ≤1.6Mpa (PN16) and the temperature is ≤200°C (plain water, steam, oil, etc.).

3. Materials and standards
● Valve body material: cast iron (HT200), cast steel (WCB), stainless steel (304/316), etc.

● Standard Specifications:

● GB/T 8464: Specification for Threaded Valves of General National Standard.

● GB/T 7306: 55° sealing pipe thread standard (G thread).

● JB/T 7746: Forged Steel Globe Valve Standard with Reduced Diameter (Reference for Some Threaded Valves).

4. Application Scenarios
● Medium: Water, steam, oil, corrosive liquid (stainless steel required).

● Industry: building water supply and drainage, heating, ventilation and air conditioning, chemical industry, petroleum industry, small industrial pipelines, etc.