INDUSTRY COMPONENT

Disc/Plug

Disc/Plug is a critical sealing component in pressure relief valves that opens to release excess pressure and closes to maintain system integrity.

Component Specifications

Definition
The Disc/Plug is a precision-engineered component in pressure relief valves that serves as the primary sealing and pressure-release mechanism. It consists of a disc-shaped or plug-shaped element that seats against a valve seat under normal operating conditions. When system pressure exceeds the predetermined set pressure, the disc/plug lifts off the seat, allowing fluid or gas to escape and relieve pressure. The component must maintain tight sealing during normal operation while responding precisely to pressure changes to prevent system damage or failure.
Working Principle
The Disc/Plug operates on the principle of force balance. Under normal conditions, spring force and system pressure keep the disc/plug seated against the valve seat, creating a seal. When pressure exceeds the set point, the upward force from the pressure overcomes the downward spring force, causing the disc/plug to lift. This creates an opening for pressure relief. Once pressure drops below the reseat pressure, the spring force pushes the disc/plug back onto the seat, resealing the valve.
Materials
Typically manufactured from corrosion-resistant materials such as stainless steel (304, 316), brass, or specialized alloys. Sealing surfaces may include elastomers like Viton, EPDM, or PTFE for enhanced sealing. High-temperature applications may use Inconel or other nickel-based alloys.
Technical Parameters
ParameterTypical rangeNotes & selection driver
Diameter10-200 mm
Lift Height5-25% of seat diameter
Leakage ClassANSI/FCI 70-2 Class IV-VI
Pressure ClassANSI 150-2500, PN10-PN400
Set Pressure Range0.1-100 bar
Operating Temperature-40°C to 400°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards
ISO 4126, ASME BPVC Section VIII, API 526, DIN 3320

Parent Products

This component is used in the following industrial products

Engineering Analysis

Risks & Mitigation
  • Seal failure leading to leakage
  • Sticking due to corrosion or contamination
  • Inaccurate pressure setting
  • Fatigue failure from cyclic operation
  • Thermal expansion mismatch
FMEA Triads
Trigger: Corrosion or erosion of sealing surfaces
Failure: Leakage during normal operation
Mitigation: Use corrosion-resistant materials, regular inspection, protective coatings
Trigger: Contamination or fouling
Failure: Disc/plug sticking, failure to open at set pressure
Mitigation: Install filters/strainers, regular maintenance, proper system flushing
Trigger: Spring fatigue or set point drift
Failure: Inaccurate relief pressure
Mitigation: Regular calibration, use of certified springs, temperature compensation

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance
Seating surface flatness within 0.0005 inches per inch, surface finish 16-32 microinches Ra
Test Method
Hydrostatic/pneumatic seat leakage test per API 527, set pressure verification per ASME PTC 25

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation
Request current drawings, revision history, and a signed specification sheet.
Manufacturing capability
Verify equipment lists, process limits, capacity, and representative production evidence.
Inspection readiness
Confirm test methods, calibrated equipment, sampling plans, and traceable reports.
Supplier transparency
Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Disc/Plug

Manufacturer profiles associated with Disc/Plug.

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Frequently Asked Questions

What is the difference between a disc and a plug in pressure relief valves?

A disc is typically flat and seats against a flat or angled seat, while a plug is conical and fits into a matching seat. Discs are common in conventional relief valves, while plugs are often used in pilot-operated valves. Both serve the same function but have different geometric designs.

How often should disc/plug components be inspected or replaced?

Inspection frequency depends on service conditions. Generally, inspect annually or after every relief event. Replace if there is visible wear, corrosion, or damage to sealing surfaces. Follow manufacturer recommendations and regulatory requirements for specific applications.

Can disc/plug components be repaired or must they be replaced?

Minor surface imperfections can sometimes be repaired by lapping or machining, but this requires specialized equipment and expertise. Significant damage, corrosion, or wear typically requires replacement to ensure proper sealing and safety performance.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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