Secondary Seal (O-ring/Gasket): Inner Diameter 5-500 mm

Q: What is the difference between primary and secondary seals in gas seal assemblies?

Primary seals handle main operational sealing under normal conditions with dynamic movement, while secondary seals provide backup containment during primary seal failure, pressure surges, or maintenance periods, typically operating under static conditions.

Q: How often should secondary seals be replaced in industrial equipment?

Replacement intervals depend on operating conditions, but typically range from 12-36 months. Regular inspection for compression set, cracking, or chemical degradation is recommended during maintenance shutdowns.

Component Specifications

Definition

A secondary seal, typically in the form of an O-ring or gasket, is installed in gas seal assemblies as a redundant sealing mechanism to contain process fluids or gases. It operates in conjunction with primary seals to enhance system reliability by providing an additional barrier against leakage, particularly during primary seal failure, pressure fluctuations, or thermal cycling. This component ensures operational safety and environmental compliance in industrial applications.

Working Principle

The secondary seal functions by creating a physical barrier through elastic deformation when compressed between mating surfaces. It fills microscopic gaps and irregularities, preventing fluid or gas passage. In gas seal assemblies, it typically operates under static or low-dynamic conditions, maintaining sealing integrity through material resilience and proper gland design, even when the primary seal experiences wear or transient pressure changes.

Materials

Common materials include Nitrile Rubber (NBR) for oil resistance, Fluorocarbon (FKM/Viton) for chemical and high-temperature applications, Ethylene Propylene Diene Monomer (EPDM) for steam and weathering resistance, and Polytetrafluoroethylene (PTFE) for extreme chemical compatibility. Material selection depends on temperature range (-40°C to 250°C), pressure (up to 1000 psi), media compatibility, and environmental factors.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Hardness	70-90 Shore A
Inner Diameter	5-500 mm
Compression Set	<25%
Pressure Rating	Up to 1000 psi
Tensile Strength	10-25 MPa
Temperature Range	-40°C to 250°C
Cross Section Diameter	1.5-10 mm

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 3601, DIN 3771, AS 568A, SAE J515

Parent Products

This component is used in the following industrial products

Gas Seal Assembly

A critical sealing component within a rotary gas injector that prevents gas leakage between rotating and stationary parts.

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Engineering Analysis

Risks & Mitigation

Compression set leading to seal failure
Chemical degradation from process media
Thermal aging at high temperatures
Improper gland design causing extrusion
Installation damage during assembly

FMEA Triads

Trigger: Material incompatibility with process fluids
Failure: Swelling, cracking, or chemical degradation of seal
Mitigation: Conduct material compatibility testing and select appropriate elastomer compounds (e.g., FKM for aggressive chemicals)

Trigger: Excessive compression beyond design limits
Failure: Permanent deformation (compression set) and loss of sealing force
Mitigation: Follow gland design standards (ISO 3601) and maintain proper compression ratios (typically 15-30%)

Trigger: Thermal cycling beyond material limits
Failure: Thermal aging, hardening, and loss of elasticity
Mitigation: Select materials with appropriate temperature ratings and consider thermal expansion in gland design

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±0.10 mm on cross-section diameter, ±0.15% on inner diameter per ISO 3601-1

Test Method

Leakage testing per ISO 15848, compression set testing per ASTM D395, material verification per ASTM D2000

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

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Manufacturers of Secondary Seal (O-ring/Gasket)

Manufacturer profiles associated with Secondary Seal (O-ring/Gasket).

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Frequently Asked Questions

What is the difference between primary and secondary seals in gas seal assemblies?