Pilot Operated Relief Valve
Pilot-controlled valve for precise pressure control and high-capacity relief.
Technical Specifications
| Type | Pilot Operated |
| Size Range | 1" to 8" (25 mm to 200 mm) |
| Body Materials | Carbon Steel, Stainless Steel |
| Trim | SS316, Stellite |
| Set Pressure | Customer specified |
| End Connections | Flanged |
| Pressure Rating | As per set pressure requirement |
| Standards | API 520, API 526, ASME Section VIII |
Applications
High-capacity relief, gas processing, pipelines
About the Pilot Operated Relief Valve
The pilot operated relief valve (PORV) uses a small self-contained pilot valve that senses inlet pressure and controls the operation of a much larger main valve. In the closed position, line pressure acting on top of the main valve piston (dome pressure, supplied via the pilot valve from the inlet) holds the piston down against the seat with a force proportional to line pressure - the seating force increases with pressure, producing a tighter seal the more the system is pressurised below set point. At set pressure, the pilot valve opens, venting the dome pressure rapidly to atmospheric or back-pressure; the line pressure now underneath the main piston lifts it fully in milliseconds, opening the full inlet bore to relieve flow at very high capacity.
This load-controlled (as opposed to spring-loaded) seating mechanism gives pilot operated relief valves three significant advantages over conventional spring-loaded safety valves: first, the set pressure accuracy is typically ±1% versus ±3–5% for spring valves, as the pilot senses inlet pressure directly; second, the main valve operates at pressures up to 98% of set point without simmering or leakage (a spring valve typically begins simmering at 90%); third, for a given inlet size, the main valve provides substantially higher relieving capacity because the full piston area (not just the orifice area) is used for seating. Vajra Industrial Solutions supplies pilot operated relief valves in sizes 1" to 8" to API 520 and API 526.
Where It's Used
Key industries and applications for the Pilot Operated Relief Valve
Gas processing and compression
pilot operated relief valves on compressor discharge coolers, gas scrubber vessels, and dehydration unit pressure vessels where ±1% set pressure accuracy prevents nuisance opening during normal operations near the MAWP
Pipeline overpressure protection
large-capacity Carbon Steel PORVs on natural gas and liquid petroleum pipelines for compressor station station-relief duty; high-capacity full-bore opening protects the entire downstream pipeline section
Thermal relief on liquid-full systems
SS316 PORVs on heat exchanger tube sides and liquid-full pipe sections susceptible to thermal expansion overpressure when isolated between two block valves; very small relieving quantity makes ±1% accuracy critical
Refinery high-pressure reactors
PORVs on hydrotreater, hydrocracker, and reformer reactor vessels where operating pressure is 90–95% of MAWP; conventional spring valve would simmer at normal operating pressure
Storage terminal and LPG bullets
PORVs on LPG and NGL storage bullets for fire case relief; remote pilot sensing allows the pilot to be located away from the flame impingement zone while the main valve remains at the vessel nozzle
How to Choose the Right Pilot Operated Relief Valve
Specify a pilot operated relief valve when: (a) normal operating pressure exceeds 90% of MAWP (conventional spring valve would simmer); (b) very high relieving capacity at a compact inlet connection is required; (c) set pressure accuracy of ±1% or better is needed for process or safety system design; or (d) the application involves thermal relief of liquid-full systems where very small orifice plus precise set pressure is critical. For simple boiler and pressure vessel protection at operating pressures well below MAWP, a conventional spring-loaded safety valve is adequate and simpler.
Popular Configurations
Most commonly ordered specifications for the Pilot Operated Relief Valve
Frequently Asked Questions
About Pilot Operated Relief Valve - ordering, specs, delivery & compliance
What standards does the Pilot Operated Relief Valve comply with?+
Our Pilot Operated Relief Valve complies with API 520, API 526, ASME Section VIII. All products are manufactured to international standards and come with full material test reports (MTR), dimensional inspection reports, and hydrostatic test certificates on request.
What materials are available for the Pilot Operated Relief Valve?+
The Pilot Operated Relief Valve is available in Carbon Steel, Stainless Steel. Material selection depends on your process fluid, temperature, pressure, and corrosion requirements.
What is the delivery lead time for Pilot Operated Relief Valve?+
Standard stock sizes are available for immediate dispatch from our Vadodara warehouse. Custom sizes and special materials typically have a lead time of 2–6 weeks depending on specifications. We serve customers across India within 1–7 business days and export to the Middle East, Southeast Asia, Europe, and the Americas with full export documentation.
Can I get a custom Pilot Operated Relief Valve for a specific application?+
Yes. Vajra Industrial Solutions supplies custom-engineered safety & relief valves for specific process conditions. Submit your technical requirements - including pressure class, temperature range, fluid type, end connections, and any special trim or coating needs - via our RFQ form or WhatsApp, and our engineering team will respond within 24 hours.
What pressure ratings are available for the Pilot Operated Relief Valve?+
The Pilot Operated Relief Valve is available in pressure ratings of As per set pressure requirement. Higher-pressure classes are available for critical service applications in oil & gas, power generation, and chemical processing.
How do I request a quote for the Pilot Operated Relief Valve?+
You can request a quote by clicking the "Request Quote" button on this page, filling out our RFQ form at vajravyuh.com/rfq, emailing us at sales@vajravyuh.com, or WhatsApping us directly at +91-9979774557. Please include quantity, size, pressure class, material grade, and end-connection type for the fastest response.
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