Flexible graphite rings are sealing elements manufactured from high-purity expanded graphite through compression molding. They inherit graphite's exceptional thermal stability and chemical resistance while possessing excellent flexibility and resilience, making them ideal sealing solutions for extreme conditions involving high temperatures, strong corrosion, and rapid temperature changes.

Core Characteristics

Characteristic	Technical Parameter	Performance Advantage
Temperature Range	-200℃ ~ +3000℃ (Inert gas)	Extreme temperature capability
Compression Rate	15% ~ 40%	Adapts to flange surface imperfections
Recovery Rate	≥ 25%	Maintains seal under thermal cycling
Thermal Conductivity	50-150 W/(m·K) (Parallel to surface)	Excellent heat dissipation
Chemical Resistance	pH 0-14 (Except strong oxidizers)	Broad chemical compatibility

Product Specifications

Parameter	Standard Range	Special Customization
Inner Diameter	Φ3 ~ Φ2000mm	Φ1 ~ Φ5000mm
Cross-Section	1.5mm ~ 20mm	0.5mm ~ 50mm
Density	0.8 ~ 1.8 g/cm³	0.6 ~ 2.2 g/cm³
Tolerance Grade	±0.1mm (Standard)	±0.05mm (Precision grade)

Material Grade Selection

Material Grade	Characteristics	Suitable Applications
Nuclear Grade	S ≤ 50 ppm, Cl ≤ 50 ppm	Nuclear power, Semiconductor
Food Grade	Heavy metals < 10 ppm	Pharmaceutical, Food processing
High Purity	Carbon content ≥ 99.99%	acuum furnace, Analytical instruments
Reinforced Grade	With metal insert	High pressure, Mechanical seals

Processing Guide

1. Installation Parameters

Installation Step	Technical Requirement	Precautions
Flange Gap	≤ 0.5mm	Avoid extrusion
Compression Rate	20% ~ 35% (Recommended)	Excessive compression causes failure
Surface Finish	Ra ≥ 1.6μm (Optimal)	Prevents slippage
Bolting Sequence	Cross tightening	Ensures even compression

2. Special Treatments

· Foil Wrapping: 0.1mm stainless steel foil for handling fragile rings

· Surface Coating: PTFE coating for acidic environments

· Edge Reinforcement: Metal core reinforcement for high pressure cycling

Typical Applications

1. Industrial Sector

Application Scenario	Technical Solution	Benefit Improvement
High Temperature Flanges	3mm section, 1.3 g/cm³ density	Replaces asbestos, withstands 800℃
Heat Exchangers	2mm section, metal inserted	Zero leakage in thermal cycling
Reactor Lids	6mm section, reinforced type	Maintenance cycle extended 3x

2. Special Fields

· Semiconductor: Nuclear grade for CVD equipment

· Aerospace: High purity grade for rocket engine seals

· Hydrogen Energy: Special treated for hydrogen embrittlement resistance

Comparison with Traditional Materials

Comparison Item	Flexible Graphite	PTFE	Compressed Asbestos
Max Temperature	3000℃ (Inert)	260℃	500℃
Chemical Resistance	★★★★☆	★★★★★	★★★☆☆
Compression Resilience	★★★★★	★★★☆☆	★★☆☆☆
Installation Flexibility	★★★★★	★★★★☆	★★★☆☆

Quick Selection Guide

Working Condition	Recommended Specification	Technical Basis
High Temperature Oxidizing	With oxidation resistant coating	Service life >2 years at 450℃
Ultra-high Vacuum	Nuclear grade, 1.6 g/cm³	Outgassing rate <10⁻¹¹ mbar·L/s
Strong Acid Alkali	Food grade + PTFE coating	Resists 98% H₂SO₄, 50% NaOH
Rapid Thermal Cycling	25% compression rate	Withstands ΔT>300℃/min

Quality Certification

Standard	Test Item	Indicator Requirement
ISO 15867	Chloride Content	≤ 50 ppm (Nuclear grade)
FDA 21 CFR	Heavy Metals	≤ 10 ppm
ASTM F37	Compression Recovery	≥ 25%
ISO 13354	Sealing Performance	Zero leakage @ 1000℃