Pressure Relief Valve, Pilot-Operated, 3 in × 600# RF, 1,480 psi, Sour Service

The Pressure Relief Valve, Pilot-Operated, 3 in × 600# RF, 1,480 psi, Sour Service is a pilot-operated pressure relief valve rated for 1,480 psi working pressure (ANSI 600 class), 3 in 600# ANSI Raised-Face Flange. NACE MR0175 / ISO 15156 sour-service compliant.

Pilot-operated relief design — a pilot valve senses line pressure and modulates the dome pressure on the main valve. Modulating action gives a tighter setpoint band (within 3-5% of set) and chatter-free operation across the full discharge range. Suitable for tight-shutoff service on gas / vapour lines and for installations where multiple relief valves operate in parallel.

Set pressure is made-to-order. Specify the required set pressure on the RFQ — typical setpoints range from 50% to 100% of the body pressure rating. Indus calibrates and seals the valve at the spec'd setpoint with a witness-test certificate.

Construction

• Type: Pressure Relief — Pilot-Operated
• Nominal size: 3 in
• Body material: Cast WCB carbon steel — NACE MR0175 compliant
• Trim (disc + seat + nozzle): 316SS disc + nozzle, NACE-compliant Inconel X-750 spring
• Seal / soft goods: PEEK back-up + HNBR primary seals
• Inlet: 3 in 600# ANSI Raised-Face Flange
• Outlet: 4 in 300# ANSI Raised-Face Flange

Performance

Working pressure 1,480 psi. Set pressure factory-calibrated and witness-tested per API 526. NACE MR0175 / ISO 15156 sour-service compliant — material class EE.

Applications

• HP sour-gas processing relief
• Amine plant absorber over-pressure
• Sweetening unit safety
• API 526 stamped HP installations

Compliance

• API 526 (steel pressure relief valves) and / or ASME Section VIII Division 1
• NACE MR0175 / ISO 15156 (sour-service)
• Calibration and witness-test certificate at specified set pressure
• Mill test reports per EN 10204 3.1 / 3.2

How to order

Confirm (a) line operating pressure (typically 90% of set pressure), (b) required set pressure (the over-pressure protection threshold), (c) line fluid and temperature (affects orifice sizing per API 520), (d) discharge routing (atmosphere / relief header / closed flare), (e) service class (standard vs sour), (f) any required certifications (ASME UV stamp, API monogram, witness-test attendance). Indus quotes ex-works OEM with calibration and pre-shipment test certificates.

Companion products

Pair with a matched-rated isolation valve upstream (typically a manual gate or ball valve, locked-open) and a manual block valve on the discharge line for service / maintenance access. For relief headers handling H₂S, ensure the discharge piping is also NACE MR0175 compliant. Indus also supplies relief-system engineering services (orifice sizing per API 520, blowdown / over-pressure analysis) on request.