Union Bonnet Needle Valves-Tube Socket Weld

Union Bonnet Needle Valves-Tube Socket Weld

SIYelectric Union Bonnet Needle Valves are designed for precise flow control of liquids and gases in industrial process systems, instrumentation lines, laboratory equipment, and calibration applications.

The valve uses a long tapered needle stem matched with a precision-machined seat. This structure allows the flow opening to be adjusted gradually, making the valve suitable for applications where fine control is required instead of simple on/off operation.

The union bonnet design allows easier disassembly and maintenance compared with some fixed bonnet structures, while maintaining reliable operation in demanding process and instrumentation systems. These valves are commonly used for sampling lines, purge systems, pressure testing, calibration loops, gas distribution, liquid distribution, and high-pressure fluid handling.

Applications

Flow Regulation

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

Low-flow process control
Suitable for instrument lines, sampling points, purge lines, and auxiliary process lines where small flow changes must be adjusted carefully.

Testing and Calibration

Instrumentation calibration support
Commonly used in laboratories, pressure test systems, calibration benches, and process control applications to regulate test liquids or gases.

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

Gas and Liquid Distribution

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

Flexible maintenance structure
The union bonnet structure can make inspection and maintenance more convenient where periodic servicing is required.

Pressure Control

Sensitive fluid handling
Union bonnet needle valves are often used in fuel systems, hydraulic systems, pneumatic systems, high-pressure lines, and critical fluid control applications where pressure and flow require careful adjustment.

Hazardous or demanding media
For corrosive, toxic, flammable, high-pressure, or high-temperature fluids, the valve material, sealing structure, pressure rating, and connection type should be selected according to actual operating conditions.

Advantages

• Union bonnet design supports easier inspection, disassembly, and maintenance.
• Tapered needle stem allows gradual and precise flow control.
• Suitable for liquids, gases, test fluids, and process media.
• Ideal for instrumentation, sampling, purge, testing, calibration, and pressure control applications.
• Compact valve structure helps reduce potential leakage points.
• Applicable to high-pressure and demanding process conditions, depending on material and sealing selection.
• Multiple material and connection options can be selected according to process medium, pressure, temperature, and installation requirements.