Thermal Power Plant Valves

Types of Valves Used in Thermal Power Plants

Thermal power plants use different types of valves for controlling steam, water, fuel, air, and other fluids under high pressure and temperature conditions. Below are the major valve types along with specifications, technical details, applications, approximate prices, and pictures.

1. Gate Valve

Used for full open or full close operation in steam and water lines.

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Technical Details

  • Operation: Linear motion

  • Function: Isolation valve

  • Flow Direction: Bidirectional

  • Pressure Rating: ANSI 150 to ANSI 2500

  • Temperature Range: Up to 650°C

  • Materials:

    • Cast Steel

    • Stainless Steel

    • Alloy Steel

  • End Connections:

    • Flanged

    • Butt Weld

  • Actuation:

    • Manual

    • Electric

    • Pneumatic

Specifications

Parameter Typical Range
Size 15 mm – 600 mm
Pressure Class 150–2500
Body Material WCB, WC6, WC9, SS316
Seat Type Metal seated

Applications

  • Main steam lines

  • Boiler feed water systems

  • Condensate systems

Approximate Price

  • Small industrial type: ₹4,000 – ₹15,000

  • High-pressure power plant type: ₹40,000 – ₹4,50,000

2. Globe Valve

Used for throttling and regulating flow.

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Technical Details

  • Operation: Linear motion

  • Function: Flow regulation

  • Better throttling compared to gate valve

  • Higher pressure drop

Specifications

Parameter Typical Range
Size 15 mm – 400 mm
Pressure Rating ANSI 150–2500
Temperature Up to 650°C
Trim Material SS304, SS316, Stellite

Applications

  • Steam control

  • Boiler blowdown systems

  • Feedwater control

Approximate Price

  • ₹5,000 – ₹3,00,000

3. Ball Valve

Used for quick shut-off applications.

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Technical Details

  • Quarter-turn valve

  • Fast operation

  • Low pressure drop

  • Excellent sealing performance

Specifications

Parameter Typical Range
Size 10 mm – 300 mm
Pressure Class ANSI 150–900
Temperature Up to 450°C
Seat Material PTFE, Metal

Applications

  • Fuel oil lines

  • Water systems

  • Chemical dosing systems

Approximate Price

  • ₹2,000 – ₹1,50,000

4. Butterfly Valve

Widely used in cooling water and air systems.

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Technical Details

  • Quarter-turn operation

  • Lightweight design

  • Suitable for large diameter pipelines

Specifications

Parameter Typical Range
Size 50 mm – 3000 mm
Pressure Rating PN10 to PN40
Temperature Up to 400°C
Disc Material SS316, Ductile Iron

Applications

  • Cooling water systems

  • Air ducts

  • Circulating water systems

Approximate Price

  • ₹3,000 – ₹5,00,000

5. Check Valve (Non-Return Valve)

Prevents reverse flow in pipelines.

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Technical Details

  • Automatic operation

  • Prevents backflow

  • Low maintenance

Specifications

Parameter Typical Range
Size 15 mm – 600 mm
Pressure Class ANSI 150–2500
Temperature Up to 600°C

Applications

  • Boiler feed pumps

  • Condensate systems

  • Steam pipelines

Approximate Price

  • ₹2,500 – ₹2,00,000

6. Safety Valve

Protects equipment from overpressure.

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Technical Details

  • Automatic pressure relief

  • Spring-loaded mechanism

  • Critical safety component

Specifications

Parameter Typical Range
Set Pressure As per boiler design
Temperature Up to 650°C
Material Alloy Steel, SS

Applications

  • Boilers

  • Steam drums

  • Pressure vessels

Approximate Price

  • ₹8,000 – ₹6,00,000

7. Control Valve

Used for automatic flow and pressure control.

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Technical Details

  • Automated valve operation

  • Precise flow control

  • Integrated with DCS/PLC systems

Specifications

Parameter Typical Range
Size 15 mm – 500 mm
Actuator Type Pneumatic/Electric
Control Signal 4–20 mA
Pressure Class ANSI 150–2500

Applications

  • Steam temperature control

  • Feedwater regulation

  • Turbine bypass systems

Approximate Price

  • ₹15,000 – ₹10,00,000

8. Pressure Reducing Valve (PRV)

Reduces high-pressure steam to lower usable pressure.

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Technical Details

  • Automatic pressure reduction

  • Stable downstream pressure

  • Suitable for steam systems

Specifications

Parameter Typical Range
Pressure Reduction Up to 100 bar
Temperature Up to 540°C
Material Alloy Steel

Applications

  • Auxiliary steam systems

  • Turbine steam lines

  • Process steam distribution

Approximate Price

  • ₹20,000 – ₹8,00,000

Common Valve Materials in Thermal Power Plants

Material Usage
WCB Cast Steel General steam and water
WC6 / WC9 Alloy Steel High temperature steam
Stainless Steel SS304/316 Corrosion resistance
Duplex Steel Aggressive fluids
Stellite Trim High wear resistance

Common Valve Standards

Standard Purpose
ASME B16.34 Valve design
API 600 Steel gate valves
API 602 Compact steel valves
API 598 Valve testing
ANSI Classes Pressure ratings

Valve Actuator Types

Type Application
Manual Handwheel Small valves
Electric Actuator Remote operation
Pneumatic Actuator Fast control
Hydraulic Actuator Heavy-duty systems

Important Selection Factors

  • Operating pressure

  • Steam temperature

  • Fluid type

  • Flow rate

  • Corrosion resistance

  • Maintenance requirements

  • Automation compatibility