Pilot-Operated Safety Valve

Pilot-Operated Safety Valve (POSV) relies on process line pressure rather than a heavy mechanical spring to maintain a tight seal. A compact, precision pilot valve continuously monitors upstream conditions, holding the main valve disk closed via internal pressure loading in the dome chamber.

Because system pressure reinforces the seating force, these units remain bubble-tight up to 98% of set pressure. Upon reaching the pressure threshold, the pilot vents the dome, creating an instantaneous pressure imbalance that lifts the main piston or diaphragm to discharge flow. Once pressure normalizes, the pilot recharges the dome chamber to snap the main valve shut without chatter or simmer.

Practical Advantages in the Field

• Eliminates High-Pressure Seepage: Traditional direct-acting valves tend to simmer or leak as system pressure gets close to the set point. POSVs maintain maximum seating force right up until activation.

• Immunity to Back-Pressure: Built-in pressure balancing prevents fluctuating back-pressure in discharge manifolds from shifting the valve’s opening set-point.

• Substantial Mass & Space Savings: Replacing massive spring bonnets on 6″ to 16″+ lines reduces structural weight on pipe racks and minimizes vibration stress on nozzles.

• On-Line Testing Capabilities: Integrated field-test connections allow technicians to verify set pressure using external air/nitrogen without taking the main line offline.

• Modulating Flow Control: Available with modulating pilots that open proportionately to the over-pressure event, venting only the exact volume needed to prevent product waste.

Brands We Provide

• GCC VALVES

• SVR GLOBAL

• FLOWORK

• EMERSON

• KITZ CORPORATION

Typical Deployments

• High-pressure natural gas transmission pipelines and compressor stations

• Offshore production platforms, FPSOs, and subsea tie-ins

• Ethylene units, hydrocarbon cracking towers, and refinery blowdown systems

• Large-scale LNG storage tanks, cold boxes, and marine loading arms

• High-output utility steam lines and superheaters

Our Pilot-Operated Safety Valves at AustraliaValves.com are manufactured and tested in accordance with international safety standards, complete with UL/FM options for specialized applications, custom pilots, and remote sensing lines across Australia.

For sizing calculations, pilot selection, or to request a quote, please contact us.