INDUSTRY COMPONENT

Disc and Seat

Critical sealing interface in steam generator pressure relief valves that regulates pressure release.

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Component Specifications

Definition
The disc and seat form the primary sealing mechanism in a steam generator pressure relief valve assembly. The disc is the movable component that lifts off the stationary seat to allow steam discharge when system pressure exceeds the set point, then reseals against the seat when pressure normalizes. This interface must maintain leak-tight closure under normal operating conditions while providing reliable, repeatable opening during overpressure events.
Working Principle
The disc is held against the seat by spring force or system pressure during normal operation. When upstream pressure exceeds the set pressure, the resulting force overcomes the spring force, lifting the disc from the seat to create a flow path for steam discharge. As pressure decreases below the reseat pressure, the spring force returns the disc to contact with the seat, re-establishing the seal.
Materials
Typically manufactured from corrosion-resistant alloys such as stainless steel (AISI 316, 17-4PH), Inconel 718, or Stellite for high-temperature steam applications. Hard-facing materials like tungsten carbide may be applied to sealing surfaces for enhanced wear resistance.
Technical Parameters
  • Leakage Class ANSI/FCI 70-2 Class IV or better
  • Surface Finish Ra ≤ 0.4 μm on sealing surfaces
  • Flatness Tolerance ≤ 0.0005 mm/mm
  • Set Pressure Range 0.1-25 MPa
  • Operating Temperature Up to 400°C
Standards
ISO 4126-1, ASME BPVC Section VIII, API 526

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Disc and Seat.

pressure relief valve disc valve seat steam generator safety valve pressure control component industrial valve parts sealing interface Disc and Seat Disc and Seat in Machinery and Equipment Manufacturing

Parent Products

This component is used in the following industrial products

Steam Generator Pressure Relief Valve Assembly

Safety valve assembly for industrial steam generators that prevents overpressure conditions.

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Engineering Analysis

Risks & Mitigation
  • Seal failure leading to continuous leakage
  • Sticking or binding preventing proper operation
  • Erosion reducing sealing effectiveness
  • Corrosion compromising material integrity
FMEA Triads
Trigger: Contaminant accumulation on sealing surfaces
Failure: Prevent proper disc-seat contact, causing leakage
Mitigation: Implement regular cleaning procedures and install upstream strainers
Trigger: Thermal stress from rapid temperature changes
Failure: Warping or cracking of disc or seat components
Mitigation: Use materials with matched thermal expansion coefficients and implement controlled warm-up procedures

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Dimensional tolerances per ASME Y14.5, sealing surface flatness within 0.0005 mm/mm, surface roughness Ra ≤ 0.4 μm
Test Method
Hydrostatic testing per ASME BPVC Section VIII, seat leakage testing per API 527, set pressure verification using certified test stands

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Frequently Asked Questions

What causes disc and seat wear in pressure relief valves?

Primary wear mechanisms include erosion from high-velocity steam flow during discharge, corrosion from chemical contaminants in steam, galling from metal-to-metal contact during operation, and thermal cycling effects that cause material degradation.

How often should disc and seat components be inspected?

Visual inspection should occur during routine maintenance shutdowns (typically annually). Dimensional inspection and leakage testing should be performed according to manufacturer recommendations or regulatory requirements, usually every 12-24 months depending on service conditions.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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