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Product Overview

 

Industrial pressure relief valves function as the final mechanical safety layer in pressurized systems. When system pressure exceeds predetermined safe limits, the valve opens dynamically to discharge media and prevent catastrophic vessel failure.

 
 

Product Types & Working Principle

Direct Spring-Loaded Valves

System pressure acts directly underneath the disc against a calibrated spring force. When force exceeds spring tension, the disc lifts instantly (pop action) or proportionally (proportional action). Utilized in standard liquid and gas applications.

Pilot-Operated Valves

Consist of a main valve and a pilot control valve. System pressure maintains the main valve disc on its seat with a high sealing force up to the set point. Ideal for high-pressure, high-capacity systems operating close to the maximum allowable working pressure (MAWP).

Construction & Materials

Bodies cast in ASTM A216 WCB (carbon steel) or ASTM A351 CF8M (316 stainless steel). Trims hardened with Stellite overlay on seat interfaces to resist wire-drawing and particulate erosion. Bellows-balanced configurations available to negate the effect of backpressure.

 

Pressure Relief Valve for Oil-Filled Transformer

 

Key Features

Blowdown Adjustment: Adjustable nozzle rings control blowdown tolerances between 5% and 7% of the set pressure, minimizing media loss during venting cycles.


Metal-to-Metal Seating: Precision-lapped disc and seat geometries meet strict leakage rate standards without relying on soft elastomeric inserts that degrade under thermal cycling.


Guided Motion: Top and bottom guided stems prevent side-thrust friction and ensure repeatable pop-action dynamics across 10,000+ actuation cycles.

 

Technical Specifications

 

Specification Parameter

Standard Range / Metric

Size Range

NPS 1/2 inch to 12 inch (DN15 to DN300)

Pressure Class

ASME Class 150 to 2500 (PN16 to PN420)

Set Pressure

0.1 MPa to 42.0 MPa

Operating Temp

-196°C to +550°C

Body Materials

WCB, CF8M, CF3M, Hastelloy C276, Monel

Design Standards

API 526, ASME Section VIII, ISO 4126, PED Directives

Testing Standards

API 527, API 576

 

Applications

Steam Generation

Boiler drum overpressure protection, superheater loops, and turbine extraction lines operating up to 540°C.

Petrochemical Refining

Distillation column overhead protection, hydrocracker reactor effluent lines, and high-temperature flare headers.

Cryogenic Storage

Liquid nitrogen and LNG storage tank boil-off management utilizing low-temperature austenitic stainless steel bodies.

 

 
Manufacturing & Quality Control
 
01/

Machining: CNC horizontal boring centers maintain coaxiality tolerances within +/- 0.01 mm between the guide bushing and seat bore to prevent stem binding.

02/

Seat Lapping: Optical flat verification ensures 3-band monochromatic light interference patterns on metal seats, guaranteeing bubble-tight shutoff per standard leakage criteria.

03/

Testing Facilities: Computerized nitrogen and steam test benches verify set pressure accuracy, reseating pressure, and leakage rates. Each valve receives an individual calibration certificate traceable to serial numbers.

04/

Certifications: Pressure equipment directive compliance, quality management system integration, and material boundary integrity standards.

 

Customization

 

 

Special Trim Overlays

Stellite Gr. 6 weld overlays applied via PTA (Plasma Transferred Arc) welding for abrasive slurries or high-velocity steam service.

 

Corrosion Allowance

Thicker body walls or solid alloy construction (Inconel 625, Titanium Gr. 2) specified for sour gas environments.

 

Accessory Integration

Proximity switches for open-position feedback, rupture disc assemblies installed upstream, and special flange facings (RTJ, Tongue and Groove).

 

 

FAQ

 

Q: How do you prevent seat leakage after a valve pops under high-frequency thermal cycling?

A: Disc and nozzle seating faces undergo optical lapping to achieve surface roughness Ra < 0.2 um, paired with Stellite hard-facing to prevent deformation during rapid thermal expansion.

Q: Are your pressure relief valves certified for industrial unfired pressure vessel codes?

A: Yes. Production follows established pressure vessel rules, and valves undergo certified inspector witness testing prior to dispatch.

Q: What is the standard lead time for valves requiring sour gas compliance?

A: Standard carbon steel bodies with compliant internal trim components ship in 3 to 4 weeks. Exotic alloy bodies (Hastelloy/Monel) require 6 to 8 weeks depending on raw material mill test report (MTR) availability.

Q: Can pilot-operated valves be used in fouling or polymerizing service?

A: Pilot valves require clean, dry gas or vapor service unless filtered sense lines or remote sensing taps are installed to prevent particulate accumulation in the dome control circuit.

Q: How is the blowdown adjusted on spring-loaded models?

A: Blowdown is controlled by adjusting the lower blowdown ring, which alters the venting chamber volume around the disc holder during lift. Factory calibration sets this at 7% unless specified otherwise.

Q: What documentation is provided with each shipment?

A: Each shipment includes the Material Test Reports, Certificate of Conformance, seat leakage test reports, and maintenance/installation manuals.

Hebei Anmei Electrical Equipment Co., Ltd. is one of the most professional pressure relief valve manufacturers and suppliers in China, specialized in providing high quality products and service. Please feel free to buy customized pressure relief valve made in China here from our factory. Contact us for quotation.

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