14.07.2026 15:43
When selecting a ball valve, it is not sufficient to consider only the valve diameter or connection type. The operating pressure of the pipeline, fluid temperature, body material, seat design and connection standard must also be evaluated. One of the most important technical specifications encountered during this process is the PN pressure rating.
PN10, PN16, PN25 and PN40 indicate the nominal pressure classes of valves, flanges and other pipeline equipment. As the PN rating increases, the valve is generally suitable for higher-pressure systems. However, the PN value should not be interpreted as the exact maximum pressure that the valve can withstand at every temperature.
What Does PN Mean?
PN stands for “Pression Nominale”, meaning nominal pressure.
Approximate pressure equivalents are:
Pressure rating Approximate nominal pressure Equivalent in MPa
PN10 10 bar 1.0 MPa
PN16 16 bar 1.6 MPa
PN25 25 bar 2.5 MPa
PN40 40 bar 4.0 MPa
These values are basic references used to identify the valve pressure class. The actual maximum operating pressure may vary depending on:
Fluid temperature
Valve body material
Ball and stem material
Seat and sealing materials
Valve diameter
Connection standard
Chemical properties of the fluid
Pressure surges
Manufacturer’s pressure-temperature chart
Applicable design and testing standards
Therefore, the manufacturer’s technical data sheet should always be checked together with the pressure rating marked on the valve body.
What Is a PN10 Ball Valve?
A PN10 ball valve is designed for systems with a nominal pressure rating of 10 bar. It is generally preferred in low- and medium-pressure water installations.
Typical applications of PN10 ball valves
Clean water pipelines
Irrigation systems
Agricultural installations
Tank inlet and outlet lines
Low-pressure industrial water systems
Building mechanical installations
Low-pressure cooling lines
Advantages of PN10 ball valves
PN10 valves can provide an economical solution in applications where high pressure resistance is not required. They may reduce investment costs by avoiding unnecessarily heavy valves with higher pressure ratings.
Points to consider when selecting PN10
Even if the normal operating pressure is below 10 bar, temporary pressure increases caused by pump start-up, water hammer or closed-line pressure must be considered.
A PN10 valve should not automatically be considered suitable for every system operating at 10 bar. If the operating pressure is close to the valve’s nominal limit, a higher pressure class and an appropriate safety margin should be evaluated.
What Is a PN16 Ball Valve?
A PN16 ball valve is manufactured for a nominal pressure rating of 16 bar and is one of the most commonly used pressure classes in industrial installations.
PN16 valves are frequently used in water systems, mechanical installations, HVAC applications, compressed air lines and general industrial processes.
Typical applications of PN16 ball valves
Drinking and utility water pipelines
Industrial water systems
HVAC heating and cooling systems
Compressed air lines
Suitable sections of fire protection systems
Pump and booster systems
Water treatment plants
Factory utility lines
Low- and medium-pressure process lines
Why is PN16 widely used?
PN16 provides a balanced solution in terms of strength, cost, product availability and standard connection options. The operating pressure of many general installation systems is suitable for this class.
However, suitability should not be determined by pressure alone. As fluid temperature increases, the allowable working pressure of the body, seat and sealing materials may decrease.
What Is a PN25 Ball Valve?
A PN25 ball valve is designed for systems with a nominal pressure rating of 25 bar. It is preferred in applications requiring higher pressure resistance than PN16 valves.
Typical applications of PN25 ball valves
High-pressure industrial water lines
Pump discharge lines
Pressurized process systems
Auxiliary lines in energy plants
Compressed air systems
Suitable chemical and petrochemical processes
Pressure zones in high-rise buildings
High-pressure fire water applications
Industrial tank filling and discharge lines
Main difference between PN25 and PN16
A PN25 valve has a higher nominal pressure rating. Depending on the design, it may have:
Greater body strength
Different flange dimensions
A heavier body structure
Stronger connections
Different sealing arrangements
PN16 and PN25 flanged valves of the same DN size do not always have identical connection dimensions. The following measurements should be checked before replacement:
Flange outside diameter
Number of bolt holes
Bolt-hole diameter
Bolt-circle diameter
Flange thickness
Face-to-face length
Sealing-face type
What Is a PN40 Ball Valve?
A PN40 ball valve is designed for high-pressure systems with a nominal pressure rating of 40 bar.
In PN40 valves, not only the body but also the stem, ball, seats, seals, packing, body connections and flange structure must be designed for high-pressure operation.
Typical applications of PN40 ball valves
High-pressure industrial process lines
Power generation facilities
High-pressure pump discharge lines
Oil and gas applications
Petrochemical plants
Pressurized gas pipelines
High-pressure water systems
Compressor stations
Heavy industrial plants
Chemical processes with suitable material selection
Why does PN40 require more careful selection?
As pressure increases, the operating torque, force on the stem, seat loads and mechanical stress on the valve body may also increase.
For this reason, the following should be examined carefully:
Actuator torque
Stem strength
Seat design
Sealing system
Maximum differential pressure
The PN40 marking alone does not mean that the valve is automatically suitable for high-temperature steam, aggressive chemicals or combustible gases.
Comparison of PN10, PN16, PN25 and PN40 Ball Valves
Feature PN10 PN16 PN25 PN40
Nominal pressure class 10 bar 16 bar 25 bar 40 bar
General application Low pressure Low to medium pressure Medium to high pressure High pressure
Body design Standard May be reinforced More robust Heavy-duty
Approximate weight Lower Medium Higher Generally highest
Flange and bolt design Lighter Standard industrial Stronger High-strength
Operating torque Generally low Medium May be higher Generally higher
Cost level Economical Balanced Higher Highest
Typical use Irrigation and water General industry and HVAC Pressurized processes Heavy industry
Actuator requirement Application-dependent Application-dependent More frequently required Torque calculation is critical
These comparisons are general. Two valves with the same PN rating may have different operating limits depending on the body material, manufacturing standard, seat design and manufacturer.
What Changes as the PN Rating Increases?
1. Pressure resistance increases
A higher PN rating means that the valve is designed for a higher nominal pressure class. Actual operating pressure must still be evaluated together with temperature and material limitations.
2. Body and flange design may change
Higher-pressure valves may have greater wall thickness, stronger body joints, thicker flanges and more robust fasteners.
3. Valve weight may increase
A PN40 valve of the same DN size may be heavier than a PN10 or PN16 valve.
4. Operating torque may increase
Higher line pressure can increase the load on the ball and seats. This may affect the required lever length or actuator size.
5. Cost may increase
Higher pressure classes usually require stronger bodies, stems, seals and connection components.
6. Flange dimensions may differ
Flange dimensions can change between pressure classes. The same DN size does not automatically mean that the flanges are directly interchangeable.
Importance of Temperature in Ball Valve Selection
One of the most common mistakes is ignoring temperature.
As valve temperature increases:
The allowable stress of the body material may change.
PTFE or other soft seat materials may lose pressure capability.
Seal and packing performance may be affected.
Maximum allowable operating pressure may decrease.
Operating torque may change because of thermal expansion.
For hot water, thermal oil, steam or high-temperature processes, check:
Manufacturer’s pressure-temperature chart
Body material standard
Seat and seal materials
Maximum operating temperature
Maximum differential pressure
Thermal shock risk
Chemical compatibility of the fluid
Are PN Rating and Test Pressure the Same?
No. The PN rating and test pressure are different.
PN rating indicates the nominal pressure class of the product.
Test pressure is the pressure applied during body strength and seat leakage tests.
Body pressure test
This test verifies whether the valve body remains structurally sound under the specified test pressure.
Seat leakage test
This test checks whether unacceptable leakage occurs through the ball and seat area when the valve is closed.
The test pressure may be higher than the normal operating pressure. However, this does not mean that the valve can operate continuously at the test pressure.
Difference Between PN and DN
PN and DN describe different characteristics.
PN: Nominal pressure class
DN: Nominal diameter
Example:
DN100 PN16 flanged ball valve
DN100 indicates the nominal flow diameter.
PN16 indicates the nominal pressure class.
Flanged indicates the connection type.
Ball valves with the same DN size can be produced in PN10, PN16, PN25 or PN40 versions.
How to Select the Correct PN Rating
Determine the system pressure
Do not consider only the normal operating pressure. Also calculate:
Maximum operating pressure
Pump shut-off pressure
Water hammer
Temporary pressure surges
Check the fluid temperature
The allowable pressure may decrease as temperature increases.
Include a safety margin
The valve should not continuously operate at the limit of its nominal pressure class.
Identify the fluid
Water, steam, natural gas, compressed air, chemicals and thermal oil require different materials.
Select the body material
Common materials include:
Ductile iron
Carbon steel
Stainless steel
Brass
Bronze
Special alloys
Check the seat and seal materials
PTFE, reinforced PTFE, PEEK, metal seats and elastomers have different pressure, temperature and chemical resistance limits.
Confirm flange compatibility
Check DN, PN, flange standard, sealing-face type and bolt dimensions.
Calculate actuator torque
Electric or pneumatic actuator selection should be based on the maximum required valve torque at the highest differential pressure.
Which PN Rating Should Be Used?
Irrigation and low-pressure water systems
PN10 may be suitable when confirmed by system calculations.
Building installations and general industrial water systems
PN16 is widely used and provides a balanced solution.
High-pressure pump and process lines
PN25 may be preferred depending on pressure, temperature and surge risk.
Heavy industry and high-pressure applications
PN40 may be required. Material, seat design, pressure-temperature limits and testing standards must also be verified.
Is a Higher PN Rating Always Better?
No. A higher PN rating offers greater nominal pressure capability, but using an unnecessarily high pressure class may:
Increase product cost
Increase valve weight
Make installation more difficult
Require a larger actuator
Cause flange incompatibility
Increase spare-part costs
The correct approach is to select the pressure class that meets the system requirements with an appropriate safety margin.
Common Ball Valve Selection Mistakes
Assuming the PN value is the maximum allowable pressure at every temperature
Considering only normal operating pressure
Ignoring pump pressure surges
Ignoring fluid temperature
Failing to check the seat material
Assuming PN16 and PN25 flanges are directly interchangeable
Using a general water valve in a natural gas system
Selecting the actuator only according to DN size
Ignoring soft-seat limitations in steam applications
Failing to verify chemical compatibility
Conclusion
The main difference between PN10, PN16, PN25 and PN40 ball valves is their nominal pressure class. However, correct valve selection cannot be made based only on the PN rating.
The following must be evaluated together:
Maximum operating pressure
Fluid temperature
Fluid type
Valve body material
Ball and stem material
Seat and sealing design
DN size
Flange standard
Pressure-temperature chart
Pressure surge risk
Actuator torque requirement
Applicable product and testing standards
PN10 may be suitable for low-pressure systems, PN16 for general industrial applications, PN25 for higher-pressure processes and PN40 for heavy-duty high-pressure applications.
Frequently Asked Questions
How many bar can a PN16 ball valve withstand?
PN16 indicates a nominal pressure class of 16 bar. The actual allowable pressure depends on temperature, body material, seat design and the manufacturer’s pressure-temperature chart.
Can a PN40 valve be used instead of a PN25 valve?
It may be possible in terms of pressure resistance, but flange dimensions, face-to-face length, bolt arrangement, cost and actuator torque must be checked.
Are PN10 and PN16 flange dimensions the same?
They may be similar in some small sizes and standards, but they should not be assumed to be identical for every diameter.
Can a PN40 ball valve be used in steam systems?
The PN40 marking alone does not prove steam suitability. Body material, seat design, temperature limit and pressure-temperature data must be checked.
Does a higher PN rating mean higher quality?
No. PN indicates pressure class, not quality. Quality depends on materials, design, manufacturing, testing and quality-control procedures.
