Ball Valve FAQs & Resources

What is an anti-blowout stem in a ball valve?

An anti-blowout stem design ensures that the valve stem cannot be ejected from the body due to internal pressure—critical for high-pressure and safety-critical applications.

How does a fire-safe ball valve reseal after fire damage?

In fire-safe valves, when the soft seat melts, the secondary metal seat or graphite ring engages to maintain sealing, even under pressure. This complies with API 607 / API 6FA fire test standards.

What is a double block and bleed (DBB) ball valve?

A DBB valve provides two seating surfaces (blocks) and a vent or bleed port in between. It allows for positive isolation and safe depressurization, commonly used in pipelines and refineries.

Can ball valves be installed vertically?

Yes, ball valves can be installed in any orientation—horizontal, vertical up, or vertical down—as long as the fluid supports proper seat sealing. Actuation direction should be accessible.

What is a blow-down valve function in ball valves?

Some high-pressure ball valves include a blow-down port to release pressure or purge fluids from the system before servicing—mostly used in steam, oil, or chemical lines.

What is a V-notch or V-port ball valve?

A V-notch ball valve has a V-shaped opening in the ball or seat to enable precise throttling. It combines the tight shut-off of a ball valve with the control accuracy of a globe valve.

Can ball valves be used in vacuum systems?

Yes. Many ball valves are vacuum-compatible if their seats and stem seals can maintain leak-tight integrity under negative pressure conditions.

What is a cavity relief function in ball valves?

In trunnion ball valves, cavity relief ensures automatic pressure relief in the ball cavity (trapped fluid between seats) to prevent damage when media expands under heat.

What is the difference between full bore and reduced bore valves?

• Full bore valves have the same diameter as the pipeline—no pressure drop.
• Reduced bore valves are smaller internally—cheaper and more compact but may create minor turbulence.

What type of actuator is best for a ball valve?

• Electric actuators: Best for slow, remote control
• Pneumatic actuators: Best for fast cycling, safe zones
• Hydraulic actuators: High torque or subsea use
  Choose based on torque, speed, explosion zone rating, and automation needs.

What is LOTO (Lock Out Tag Out) compatibility in ball valves?

LOTO-compatible ball valves include locking handles or mounting brackets that can be padlocked to prevent accidental operation during maintenance or shutdown.

How to calculate torque for ball valve actuation?

Torque depends on:

• Seat type (soft vs. metal)
• Fluid pressure
• Size of the valve
• Temperature Add a 20–30% safety margin over breakaway torque for actuator selection.

Can you use ball valves for steam?

Yes—but only with:

• High-temp materials (SS316, graphite seals)
• Metal or fire-safe seats Avoid using PTFE-only seats above 200°C.

What is a vented ball valve?

A vented ball valve has a small drilled hole in the ball to relieve trapped pressure when the valve is closed. It’s used in compressed air or fuel systems.

Can I install a ball valve in explosive (ATEX) environments?

Yes, but the valve must be ATEX-certified and use anti-static design, conductive seals, and sometimes aluminum-free parts to avoid sparking.

What is the difference between a ball valve and a plug valve?

Can I replace ball valve seats and seals?

Yes, especially in 3-piece and top-entry valves, which are designed for inline maintenance. You can replace:

• PTFE / RPTFE / TFM seats
• Stem O-rings
• Body seals and graphite rings

Need Help Choosing the Right Ball Valve?

Perfect Engineers offers:

• Custom sizing
• OEM solutions
• Seat material selection
• Valve + actuator packages
• API, ISO, WRAS, and CE certified ball valves