The Octagonal Ring Gasket is a specialized form of metal ring gasket with an octagonal cross-section, primarily used for high-pressure and high-temperature flange connections (Class 600 and above). Operating on the principle of line contact sealing, it undergoes plastic deformation under bolt preload to achieve sealing. It serves as a core sealing component in fields such as petrochemicals and nuclear power.

Core Characteristics

Characteristic	Technical Parameter	Sealing Advantage
Sealing Pressure	Up to 42 MPa (ASME Class 2500)	30% higher sealing capability than oval ring gaskets
Temperature Resistance	-196°C ~ +800°C(depending on material)	Adapts to extreme temperature fluctuations
Specific Sealing Pressure	200~400 MPa (required for initial seal)	Reduces bolt load by 40% compared to flat gaskets
Recovery Rate	15%~25% (after unloading)	Compensates for thermal expansion and contraction deformation

Material Selection Guide

Material	Hardness (HB)	Applicable Media	Temperature Limit
Soft Iron (ARMCO)	60-80	Steam, Oil products	450°C
304 Stainless Steel	140-160	Weakly corrosive media	650°C
316L Stainless Steel	130-150	Media containing chloride ions	600°C
Inconel 600	150-180	High-temperature corrosive environments	800°C
Titanium Alloy	200-240	Strongly oxidizing media	550°C

Structural Dimension Standards

Flange Standard	Ring Number	Outer Diameter (mm)	Inner Diameter (mm)	Thickness (mm)
ASME B16.20	R24	168.3	127.0	127.0
EN 1092-1	D40	185.0	140.0	12.0
JIS B2404	6B	165.2	123.8	10.5

Sealing Principle

1. Three Stages of Sealing

1. Initial Compression: Bolt preload creates line contact between the gasket and the flange bevel.

2. Plastic Flow: 0.05-0.1mm plastic deformation occurs at the contact line.

3. Elastic Maintenance: 15-25% elastic recovery remains after unloading.

2. Contact Stress Distribution

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pie title Stress Concentration Areas

    "Bevel Contact Area" : 65

    "Flange Root" : 25

    "Around Bolt Holes" : 10

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Industry Application Cases

1. Hydrogenation Reactor

· Conditions: 15MPa / 450°C hydrogen environment.

· Solution: Inconel 718 octagonal gasket + special sealing grease.

· Service Life: 6 years without leakage (conventional gaskets only 2 years).

2. LNG Receiving Terminal

· Conditions: -162°C liquefied natural gas.

· Solution: 304L stainless steel, cryogenically treated type.

· Sealability: Helium leak test < 1×10⁻⁹ Pa·m³/s.

Innovative Technologies

1. Intelligent Monitoring Gasket

· Integrated fiber optic sensor:

  · Real-time monitoring of contact stress (Accuracy ±2 MPa).

  · Temperature monitoring range: -200~800°C.

  · Wireless transmission distance: 30m (Explosion-proof design).

2. Self-Energizing Structure

· Built-in shape memory alloy ring:

  · Additional preload increases by 20% when temperature > 300°C.

  · Compensates for thermal relaxation effects.

Quality Certifications