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Introduction to Graphite Rings
Graphite rings are sealing rings made from high-purity graphite material, offering excellent self-lubrication, high-temperature resistance, and chemical stability. They are an ideal sealing solution for high-temperature and high-pressure working conditions.
Core Characteristics
| Characteristic | Description | Advantages |
| Excellent High-Temperature Resistance | Can be used up to 3000°C in an inert atmosphere | Suitable for extreme high-temperature conditions |
| Outstanding Self-Lubrication | Low friction coefficient (0.04-0.12) | No external lubrication required, reducing maintenance |
| Exceptional Chemical Stability | Resistant to most acids, alkalis, and organic solvents | Suitable for corrosive media |
| Good Thermal Shock Resistance | Withstands rapid temperature changes | Ideal for thermal cycling conditions |
| Compressibility and Resilience | Certain compression and rebound capabilities | Adapts to flange unevenness |
Material Types
| Type | Characteristics | Operating Temperature (°C) | Applications |
| Flexible Graphite | Good compressibility, excellent sealing performance | -200~450 (in air) | General sealing applications |
| High-Strength Graphite | High mechanical strength, good wear resistance | -200~500 | High-speed and high-pressure conditions |
| Impregnated Graphite | Performance improved through impregnation | -200~600 | Special working conditions |
| Nuclear-Grade Graphite | High purity, low neutron absorption cross-section | -200~1000 | Nuclear industry applications |
Performance Parameters Table
Performance Indicator
Flexible Graphite
High-Strength Graphite
Impregnated Graphite
Test Standard
Density (g/cm3)
1.0~1.3
1.6~1.9
1.8~2.1
ASTM C838
Compressive Strength (MPa)
40~80
60~120
80~150
ASTM C695
Thermal Conductivity (W/m·K)
50~150
80~160
60~120
ASTM C714
Friction Coefficient
0.08~0.12
0.06~0.10
0.06~0.10
ASTM D2714
Oxidation Start Temperature (°C)
400
450
500
ASTM D7542
Structural Forms
1. Basic Graphite Rings:
· Pure graphite material
· Suitable for medium-to-low pressure static sealing
2. Reinforced Graphite Rings:
· Enhanced with metal or ceramics
· Improved mechanical strength
3. Composite Graphite Rings:
· Combined with metal components
· Suitable for high-pressure dynamic sealing
4. Cut Types:
· Straight cut
· Angled cut
· Overlap cut
Selection Guide
1. Working Condition Analysis:
· Temperature and pressure range
· Media characteristics
· Motion type (static/dynamic)
2. Material Selection:
· Use impregnated graphite for oxidizing environments
· Use high-strength graphite for high-pressure conditions
· Use nuclear-grade graphite for the nuclear industry
3. Size Determination:
· Based on sealing cavity dimensions
· Consider thermal expansion factors
· Reserve appropriate compression amount
Installation and Usage Requirements
1. Pre-Installation Preparation:
· Check sealing surface finish (Ra ≤ 1.6 μm)
· Remove impurities from sealing surfaces
· Measure cavity dimensions
2. Installation Precautions:
· Use dedicated installation tools
· Avoid rough handling
· Apply tightening force evenly
3. Usage and Maintenance:
· Regularly check compression amount
· Monitor leakage situation
· Avoid overheating
Application Fields
1. Petrochemical Industry: Reactors, compressors, valve seals
2. Power Industry: Steam turbines, gas turbine seals
3. Nuclear Industry: Nuclear reactor sealing systems
4. Aerospace: Engine sealing components
5. General Machinery: Pumps, mixer seals
Special Treatment Processes
1. Anti-Oxidation Treatment:
· Phosphoric acid impregnation
· Ceramic coating
· Metal plating
2. Reinforcement Treatment:
· Carbon fiber reinforcement
· Metal wire reinforcement
· Ceramic particle reinforcement
3. Impregnation Treatment:
· Synthetic resin impregnation
· Metal impregnation
· Inorganic salt impregnation
Graphite rings, with their unique high-temperature resistance, self-lubrication, and chemical stability, are the preferred material for high-temperature sealing applications. Through proper selection, correct installation, and appropriate maintenance, graphite rings can provide reliable sealing performance under extreme conditions. Understanding the characteristics and application ranges of different graphite materials is key to ensuring sealing effectiveness.
