Control Valves

Automated valves that regulate the flow rate or process variables (pressure, temperature, level) of a fluid within a pipeline system. They are critical components in process control loops, receiving signals from controllers to adjust their opening.

Types of Control Valves

By Motion:

Linear Motion Valves: Globe valves (most common control valve type), Gate valves (less common for control, more for on/off), Diaphragm valves, Pinch valves.

Rotary Motion Valves: Ball valves, Butterfly valves, Plug valves, Eccentric plug valves.

By Actuator Type:

Pneumatic Actuators: Diaphragm, Piston (spring-return or double-acting). Most common for industrial control.

Electric Actuators: Motorized (multi-turn, quarter-turn), Solenoid.

Hydraulic Actuators: For very high forces.

By Flow Characteristic: Equal percentage, Linear, Quick opening.

Applications in Various Industries:

Oil & Gas: Flow control, pressure regulation, temperature control in refineries, pipelines, production facilities.

Chemical & Petrochemical: Controlling reactions, blending, distillation.

Power Generation: Boiler feed water, steam flow, turbine control.

Pharmaceuticals: Precise flow control for batch processes, sterile applications.

Food & Beverage: Temperature control for pasteurization, blending ingredients.

Water & Wastewater Treatment: Flow regulation, level control.

HVAC: Regulating chilled water or steam flow.

Technology:

Valve Positioners: Receive control signals (e.g., 4-20mA) and precisely move the valve actuator to the desired position. (Pneumatic, Electro-pneumatic, Digital/Smart).

Digital Valve Controllers/Smart Positioners: Offer diagnostics, calibration, and HART/Fieldbus communication for remote monitoring and control.

Actuator Design: Spring & diaphragm, piston actuators for high force/speed.

Noise Reduction Trims: Multi-stage trims for high-pressure drop applications to reduce noise and cavitation.

Erosion-Resistant Trims: Hardened materials, special designs for abrasive slurries.

Severe Service Valves: Designed for extreme temperatures, pressures, or corrosive media.

Fugitive Emissions Control: Low-emission packing designs.

Material Selection Considerations:

Body:

• Carbon Steel (WCB, LCB): For general non-corrosive services, moderate temperatures.
• Stainless Steel (CF8M/316, CF8/304): For corrosion resistance, hygienic applications, cryogenic service.
• Alloy Steel (WC6, C5, C12): For high-temperature, high-pressure service.
• Special Alloys (Hastelloy, Monel, Duplex): For extremely corrosive or severe applications.
• Trim (Plug/Disc, Seat, Stem): Critical for control and wear. Often matching body material or harder/more corrosion-resistant materials (e.g., hardened stainless steel, Stellite overlay, ceramics).
• Packing: PTFE, Graphite, or specialized elastomers for sealing the stem, chosen for temperature, pressure, and chemical compatibility.
• Gaskets: Graphite, PTFE, spiral wound with various fillers.
• Actuator Housing: Aluminum (pneumatic), cast iron (electric).
• Diaphragm (pneumatic): Neoprene with fabric reinforcement.
• Spring (actuator): Spring steel.
• Bolting: High-strength alloy steel (e.g., ASTM A193 B7)