Pressure Relief Valve, Spring-Loaded, 3-1/8 in × 5M Flanged, 5,000 psi, Sour Service

The Pressure Relief Valve, Spring-Loaded, 3-1/8 in × 5M Flanged, 5,000 psi, Sour Service is a spring-loaded conventional pressure relief valve rated for 5,000 psi working pressure (5K class), 3-1/8 in API 6A 5M Flanged (RTJ). NACE MR0175 / ISO 15156 sour-service compliant.

Spring-loaded conventional relief design — line pressure acts directly on the disc; the spring sets the opening (set) pressure. When line pressure exceeds set, the disc lifts off the seat and discharges to atmosphere or to the relief header until line pressure drops below the reseat (blowdown) pressure. Simple, robust, and field-serviceable.

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 — Spring-Loaded
• Nominal size: 3-1/8 in
• Body material: Forged AISI 4130 — 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: 3-1/8 in API 6A 5M Flanged (RTJ)
• Outlet: 3 in 600# ANSI Raised-Face Flange

Performance

Working pressure 5,000 psi. Set pressure factory-calibrated and witness-tested per API 6A. NACE MR0175 / ISO 15156 sour-service compliant — material class EE.

Applications

• 5K wellhead Christmas tree PRV
• Sour-gas production tree relief
• Workover-rig pressure-control safety
• Subsea-adjacent surface relief

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.