Selecting the correct actuator torque is critical for reliable ball valve automation. Undersized actuators cause failure to operate; oversized actuators waste money and energy. This comprehensive reference provides breakaway torque values for standard industrial ball valves to help you size actuators correctly.
Whether you're specifying pneumatic actuators, electric actuators, or manual gear operators, the torque values in this chart serve as the baseline for your actuator selection. All values are tested breakaway torques at rated pressure differential, suitable for use with standard safety factors.
Calculate Exact Torque for Your Valve
Get precise actuator sizing based on your specific conditions. Use our free Valve Torque Calculator.
Try Actuator Sizing Calculator1. Understanding Breakaway vs Running Torque
Before consulting the torque chart, it's essential to understand the two distinct torque measurements:
Breakaway Torque (Start Torque)
This is the maximum torque required to initiate ball rotation from the fully closed position. Breakaway torque must overcome:
- Seat-to-ball static friction
- Thrust bearing preload
- Any differential pressure forces acting on the ball
- Stem seal friction
Design Basis
All torque values in this chart are breakaway torques measured at the valve's rated pressure differential. This is the standard basis for actuator sizing because it represents the maximum load the actuator must overcome.
Running Torque
Once the ball begins rotating, torque typically drops by 35-50% as the seat settles into its flow path. Running torque is the value needed to complete the stroke after initial breakaway.
Common Sizing Mistake
Never size an actuator based on running torque. If the actuator can overcome breakaway torque, it will certainly handle running torque—but the reverse is not true. Always use breakaway torque as the sizing basis.
2. Ball Valve Torque Values by Size
All torque values are in Newton-meters (N·m). Values shown are for PTFE seats at rated pressure differential. For metal seats, multiply by 1.3-1.5.
PTFE Seat Torque Values (N·m)
| Size | PN16 | Class 150 | Class 300 | ||||||
|---|---|---|---|---|---|---|---|---|---|
| DN | Min | Typical | Max | Min | Typical | Max | Min | Typical | Max |
| Small Size Valves (DN15-DN50) | |||||||||
| DN15 (1/2") | 4 | 5 | 7 | 5 | 6 | 8 | 6 | 8 | 10 |
| DN20 (3/4") | 6 | 8 | 10 | 7 | 9 | 12 | 9 | 11 | 14 |
| DN25 (1") | 8 | 10 | 14 | 10 | 12 | 16 | 12 | 15 | 20 |
| DN32 (1-1/4") | 12 | 15 | 20 | 14 | 18 | 24 | 18 | 22 | 28 |
| DN40 (1-1/2") | 15 | 20 | 26 | 18 | 24 | 30 | 24 | 30 | 38 |
| DN50 (2") | 20 | 28 | 35 | 25 | 32 | 42 | 32 | 40 | 52 |
| Medium Size Valves (DN65-DN150) | |||||||||
| DN65 (2-1/2") | 30 | 40 | 52 | 38 | 48 | 62 | 48 | 60 | 78 |
| DN80 (3") | 42 | 55 | 72 | 52 | 65 | 85 | 65 | 82 | 105 |
| DN100 (4") | 60 | 80 | 100 | 75 | 95 | 120 | 95 | 120 | 150 |
| DN125 (5") | 90 | 115 | 145 | 110 | 140 | 175 | 140 | 175 | 220 |
| DN150 (6") | 120 | 160 | 200 | 150 | 190 | 240 | 190 | 240 | 300 |
| Large Size Valves (DN200-DN600) | |||||||||
| DN200 (8") | 180 | 240 | 300 | 225 | 285 | 360 | 285 | 360 | 450 |
| DN250 (10") | 280 | 360 | 450 | 350 | 440 | 550 | 440 | 550 | 690 |
| DN300 (12") | 400 | 520 | 650 | 500 | 640 | 800 | 640 | 800 | 1000 |
| DN350 (14") | 520 | 680 | 850 | 650 | 850 | 1060 | 850 | 1060 | 1325 |
| DN400 (16") | 700 | 900 | 1125 | 875 | 1125 | 1405 | 1125 | 1405 | 1755 |
| DN450 (18") | 880 | 1140 | 1425 | 1100 | 1425 | 1780 | 1425 | 1780 | 2225 |
| DN500 (20") | 1100 | 1420 | 1775 | 1375 | 1775 | 2220 | 1775 | 2220 | 2775 |
| DN600 (24") | 1600 | 2050 | 2565 | 2000 | 2565 | 3205 | 2565 | 3205 | 4005 |
Data Notes
Values are based on standard industrial ball valves with PTFE seats tested at 20°C ambient temperature. Maximum values include allowance for seating torque and process conditions.
Metal Seat Torque Multipliers
For metal-seated ball valves, apply the following multipliers to the PTFE seat values:
| Seat Material | Torque Multiplier | Typical Application |
|---|---|---|
| PTFE / RTFE | 1.0 × | General purpose, clean service |
| Reinforced PTFE | 1.15 × | Higher temperature, abrasive media |
| PCTFE (Kel-C) | 1.2 × | Cryogenic service |
| Metal (stellite) | 1.3 - 1.5 × | High temperature, abrasive, dirty service |
| Graphite | 1.4 - 1.6 × | Fire-safe, high temperature |
3. Factors That Affect Torque Requirements
While the torque chart provides baseline values, actual torque requirements can vary based on several factors:
Pressure Differential
Higher pressure differentials increase the force on the ball, which increases seat compression and friction. For differential pressures above 10 bar, torque may increase by 5-10% per additional 10 bar.
Pressure Correction Factor:
Fp = 1 + 0.005 × (ΔP - 5)
Where ΔP is in bar. Valid for ΔP > 5 bar.
Temperature Effects
Temperature affects both the seat material and the process fluid density. PTFE seats show increased friction at temperature extremes:
- Cryogenic (-50°C and below): Torque increases 20-30% due to seat hardening
- High temperature (+200°C to +250°C): Torque increases 15-25% due to thermal expansion
- Fire-safe (graphite seats): Torque increases 40-60% vs PTFE
Process Media
Some process media act as lubricants (reducing torque), while others increase friction:
- Lubricating media (oil, fuel): 10-20% torque reduction possible
- Abrasive media (slurry, particle-laden): 15-30% torque increase
- Corrosive media: May require special seats with increased torque
Valve Lifecycle
New valves often require higher breakaway torque due to initial seat compression. After several cycles, torque typically stabilizes 10-15% below initial values.
4. Actuator Sizing from Torque Chart
Follow these steps to correctly size an actuator using the torque values:
Step 1: Select Base Torque
From the torque chart, select the "Typical" value for your valve size and pressure class. Use the "Max" value if you have limited process information or expect harsh conditions.
Step 2: Apply Corrections
Required Torque = Base Torque × Seat Factor × Pressure Factor × Temperature Factor
Step 3: Apply Safety Factor
Multiply by the appropriate safety factor:
| Actuator Type | Safety Factor | Notes |
|---|---|---|
| Pneumatic (double-acting) | 1.25 - 1.5 | Higher factor for critical service |
| Pneumatic (spring-return) | 1.4 - 1.6 | Must also verify spring torque > 1.2 × breakaway |
| Electric | 1.2 - 1.3 | Lower factor due to consistent torque output |
| Manual gear operator | 1.1 - 1.2 | Account for operator strength variation |
Example Calculation
DN80 Class 150 Ball Valve with Steam Service
Given:
- Valve: DN80, Class 150, PTFE seat
- Service: Saturated steam, 10 bar ΔP
- Temperature: 180°C
- Actuator: Pneumatic double-acting
Calculation:
- Base torque (DN80, Class 150): 65 N·m
- Pressure factor: 1 + 0.005 × (10 - 5) = 1.025
- Temperature factor (graphite seat for steam): 1.5
- Required torque: 65 × 1.025 × 1.5 = 100 N·m
- With 1.4 safety factor: 100 × 1.4 = 140 N·m
Result: Select pneumatic actuator with minimum 140 N·m torque output at minimum supply pressure.
5. Online Torque Calculator
Skip the manual calculations. Our free Valve Torque Calculator and Actuator Sizing Calculator handle all the corrections and safety factors automatically.
Free Actuator Sizing Tool
Enter your valve specs and get instant actuator recommendations with safety factors included.
Open Actuator Sizing CalculatorThe calculator also provides:
- Pneumatic actuator recommendations (double-acting and spring-return)
- Spring reserve verification for fail-safe applications
- Air consumption estimates
- PDF documentation for procurement
Conclusion
Accurate torque data is essential for reliable actuator selection. The key takeaways:
- Always use breakaway torque, not running torque, for actuator sizing
- Apply correction factors for pressure, temperature, and seat material
- Use appropriate safety factors based on actuator type and service criticality
- When in doubt, round up to the next available actuator size
- Consider long-term effects—torque may increase as seats wear or media accumulate
Download Torque Reference PDF
Get our comprehensive Ball Valve Torque Reference Card with all values organized for quick field use. Includes both metric and imperial units.
Coming soon: Sign up for our engineering newsletter to be notified when the downloadable PDF is available.
Request Early AccessFrequently Asked Questions
What is the difference between breakaway torque and running torque?
Breakaway torque is the force required to initiate ball rotation from a fully closed position, overcoming seat friction and any internal pressure forces on the ball. Running torque is the force needed to maintain rotation through the middle of the stroke, which is typically 35-50% lower than breakaway torque due to reduced seat contact pressure.
How do I calculate actuator torque requirements from the torque chart?
Select the torque value from the chart based on your valve size and pressure class, then apply a safety factor of 1.25-1.5 for pneumatic actuators and 1.2-1.3 for electric actuators. For spring-return actuators, ensure the spring torque exceeds 1.2 times the breakaway torque.
Does seat material affect ball valve torque?
Yes, seat material significantly affects torque. PTFE seats have the lowest friction coefficient (0.05-0.1) and produce the lowest torque values. Metal seats have higher friction (0.15-0.3) and can require 30-50% more torque. Reinforced PTFE or composite seats fall in between.
Why do larger valves have relatively lower torque per unit size?
Torque scales with seat circumference and contact area, but the relationship isn't linear with size. Larger valves use seats with proportionally wider contact faces, but the bearing support structure grows stronger more quickly, resulting in lower specific torque values (torque/DN) as valve size increases.
What pressure drop across the valve increases torque requirements?
When pressure drop exceeds 10-15% of the valve's pressure rating, the differential pressure creates an axial thrust on the ball that increases seat compression and friction. For every 10 bar increase in differential pressure above 5 bar, torque may increase by 5-15% depending on valve design.
How often should torque values be verified?
For new valve installations, verify torque during commissioning. For operating valves, annual verification is recommended, or whenever process conditions change significantly. Increased torque may indicate seat wear, media accumulation, or corrosion.