Why are pressure and temperature critical when selecting a valve?

In industrial facilities, valve selection is not limited only to connection diameter or valve type. The system’s operating pressure and temperature values are among the most critical criteria in proper valve selection. Valves chosen based on incorrect pressure or temperature ratings can lead to leaks, performance loss, equipment failures, and serious safety risks.

So why are pressure and temperature so important in valve selection?

Why is Pressure Important in Industrial Valves?

A valve controls the fluid passing through it under a certain pressure. When the system’s operating pressure exceeds the valve’s design strength limit, serious problems can occur.

For this reason, one of the first factors to consider in valve selection is the operating pressure.

What Does the PN Rating Mean?

You often see on valves:

• PN16
• PN25
• PN40

Values such as these indicate the maximum nominal pressure that the valve can withstand.

For example:

However, the important point to note here is:

As temperature increases, the pressure that a valve can withstand may decrease.

For this reason, selecting a valve based solely on its PN rating is not correct.

How Does Temperature Affect Valve Performance?

High temperature has a direct impact on the valve body and sealing materials.

In particular:

• steam systems,
• thermal oil lines,
• chemical plants,
• in high-temperature processes,

incorrect valve selection can lead to serious failures.

Risks Caused by High Temperature

Gasket Deformation

An unsuitable gasket material may harden or melt at high temperatures.

This situation:

• leads to loss of sealing,
• leakage,
• system inefficiency,

occurs.

Body Expansion

Metal bodies expand under temperature.

Poor-quality or unsuitable valve bodies:

• cracking,
• deformation,
• mechanical stress

may occur.

Actuator Problems

Electric and pneumatic actuators can be affected by high temperatures.

In particular:

• motor performance,
• seals
• electronic components

can be damaged.

Pressure and Temperature Must Be Evaluated Together

Many users focus only on operating pressure. However, in industrial systems, pressure and temperature must be evaluated together.

For example:

• A pressure of 10 bar may seem low,
• but if the system operates at 220°C,

a standard valve may not be sufficient.

For this reason, the manufacturer’s technical datasheets must always be reviewed.

Consequences of Incorrect Valve Selection

Valves that are not suitable for the pressure and temperature conditions can lead to the following problems:

• Valve leakage
• Gasket failure (burning)
• Sudden pressure drops
• Pipeline damage
• Actuator failures
• Energy inefficiency
• Unplanned production downtime

In particular, the safety risk is much greater in high-pressure systems.

In Which Systems Is It More Critical?

Steam Lines

Because high temperature and pressure occur together, proper valve selection is critically important.

Thermal Oil Systems

At temperatures above 300°C, special valve and gasket constructions are required.

Chemical Plants

Temperature resistance is as important as chemical resistance.

Compressed Air Systems

Sudden pressure fluctuations can affect valve lifespan.

What Should Be Considered for Proper Valve Selection?

1. Operating Pressure

The system’s maximum operating pressure must be determined.

2. Operating Temperature

Minimum and maximum temperature values must be determined.

3. Fluid Type

The properties of the fluid—such as water, steam, gas, chemicals, or thermal oil—must be taken into account.

4. Gasket Material

Gasket types such as EPDM, PTFE, and Viton should be selected according to temperature.

5. Valve Body Material

• Stainless steel
  
  
• Cast iron
• Brass
• Carbon steel

materials like these should be selected according to the application.

Importance of Safety in Industrial Systems

Incorrect valve selection not only damages equipment but can also create serious occupational safety risks.

In particular:

• high-pressure steam,
• hot oil,
• chemical fluids,

in facilities handling these fluids, proper valve selection is critically important.

Conclusion

In industrial facilities, pressure and temperature values in valve selection must always be evaluated together. Using an unsuitable valve for the system can lead to leaks, equipment failures, energy losses, and safety risks.

For proper valve selection:

• operating conditions,
• fluid type,
• temperature,
• pressure,
• gasket and body material

must be analyzed in detail.

For long-lasting, safe, and efficient systems, valve solutions suitable for the application should be preferred.