Screwed Bonnet Needle Valves Union Weld Type

Screwed Bonnet Needle Valves Union Weld Type

The SIYelectric Screwed Bonnet Needle Valve Union Weld Type is designed for precise flow control of liquids and gases in industrial process systems, instrumentation lines, testing equipment, and calibration applications.

This valve uses a long tapered needle stem matched with a precision-machined seat, allowing the flow area to be adjusted gradually and accurately. Compared with ordinary shut-off valves, this structure provides finer control for small-flow applications, pressure adjustment, sampling lines, purge systems, and high-pressure fluid handling.

The screwed bonnet design supports stable valve assembly and convenient maintenance, while the union weld type connection provides a secure welded installation suitable for demanding process lines where leakage reduction and connection reliability are important.

Applications

Flow Regulation

Precise gas and liquid control
Used in gas or liquid pipelines where the flow rate needs to be adjusted accurately and gradually.

Small-flow adjustment
Suitable for sampling systems, purge lines, instrument lines, and auxiliary process lines where fine flow control is required.

Testing and Calibration

Instrumentation calibration systems
Commonly used in laboratories, pressure testing systems, calibration benches, and process control equipment to regulate test fluids or gases.

Controlled filling and venting
Can be used with pressure gauges, pressure transmitters, manifolds, and test devices to support filling, venting, pressure release, or fine pressure adjustment.

Gas and Liquid Distribution

Industrial fluid distribution
Applied in gas and liquid distribution systems for oil & gas, chemical, pharmaceutical, food and beverage, and general industrial applications.

Reliable welded connection
The union weld type structure is suitable for systems where a stronger and more permanent process connection is preferred.

Pressure Control

Sensitive fluid handling
Used in fuel systems, hydraulic systems, pneumatic systems, high-pressure lines, and critical fluid handling applications where pressure and flow need careful control.

Demanding process media
For corrosive, toxic, flammable, high-pressure, or high-temperature media, valve material, sealing structure, pressure rating, and welding specification should be selected according to actual operating conditions.

Advantages

• Tapered needle stem design provides accurate and gradual flow regulation.
• Screwed bonnet structure supports stable assembly and reliable valve operation.
• Union weld type connection provides secure installation for demanding process pipelines.
• Suitable for precise liquid and gas flow control in instrumentation and process systems.
• Applicable to testing, calibration, sampling, purge, and pressure control applications.
• Compact valve structure helps reduce potential leakage points.
• Material and pressure rating options can be selected according to process medium, pressure, temperature, and connection requirements.