4 commonly used non-metallic insulating gaskets for pipe flanges
author: www.qishine.com
2026-02-26
In industries such as power generation, petroleum, chemicals, shipbuilding, and high-end manufacturing, electrical insulation and flange sealing are critical to ensuring the safe and stable operation of systems. Non-metallic insulating gaskets play an indispensable role, as they must not only effectively isolate electrochemical corrosion (galvanic corrosion) but also withstand the pressure, temperature, and medium corrosion of the pipeline system. Below is a professional analysis of four widely used non-metallic insulating gaskets.
1. G10 Epoxy Glass Fiber Laminated Insulating Gasket
G10 is a thermoset laminate material made from glass fiber cloth impregnated with epoxy resin and cured under high temperature and pressure. It typically appears light green or natural in color and possesses extremely high mechanical strength and rigidity.
G10 is a thermoset laminate material made from glass fiber cloth impregnated with epoxy resin and cured under high temperature and pressure. It typically appears light green or natural in color and possesses extremely high mechanical strength and rigidity.
G10 Insulating Gasket Suitable for high-pressure Flange, the appearance is usually light green, excellent compressive and flexural strength
Advantages:
Exceptionally high mechanical strength and stiffness: Excellent compressive and flexural performance, with almost no creep relaxation, making it suitable for high-pressure flanges.
Outstanding electrical insulation: Very high dielectric strength in dry environments.
Good machinability: Can be easily machined into complex-shaped gaskets, sleeves, or structural components.
Good chemical resistance: Resistant to most solvents and weak acids/bases.
Exceptionally high mechanical strength and stiffness: Excellent compressive and flexural performance, with almost no creep relaxation, making it suitable for high-pressure flanges.
Outstanding electrical insulation: Very high dielectric strength in dry environments.
Good machinability: Can be easily machined into complex-shaped gaskets, sleeves, or structural components.
Good chemical resistance: Resistant to most solvents and weak acids/bases.
Disadvantages:
Poor toughness and brittleness: Sensitive to sharp impacts and flange misalignment, which may cause cracking.
Not suitable for strong oxidizing acids and high-temperature alkali solutions.
Limited resilience and sealing followability: May require retightening under thermal cycling conditions due to expansion and contraction.
Poor toughness and brittleness: Sensitive to sharp impacts and flange misalignment, which may cause cracking.
Not suitable for strong oxidizing acids and high-temperature alkali solutions.
Limited resilience and sealing followability: May require retightening under thermal cycling conditions due to expansion and contraction.
Suitable Environments:
Static sealing applications with high pressure and low displacement, such as transformer flanges, high-voltage switchgear, and marine propeller shaft insulation.
Typical operating temperature range: -50°C to +130°C.
Media: Air, oils, seawater, and general chemical media.
Static sealing applications with high pressure and low displacement, such as transformer flanges, high-voltage switchgear, and marine propeller shaft insulation.
Typical operating temperature range: -50°C to +130°C.
Media: Air, oils, seawater, and general chemical media.
2. Klinger C4400 (Typical) Insulating Gasket
This section provides a general industry description: Typically, "Klinger C4400" refers to soft gaskets primarily reinforced with aramid fibers (e.g., Nomex) and compounded with nitrile rubber (NBR) or other polymers.
This section provides a general industry description: Typically, "Klinger C4400" refers to soft gaskets primarily reinforced with aramid fibers (e.g., Nomex) and compounded with nitrile rubber (NBR) or other polymers.
Klinger C4400 insulating gasket free of asbestos, environmentally friendly and safe
Advantages:
Excellent flexibility and compression resilience: Effectively compensates for minor flange surface irregularities and displacement caused by thermal cycles, offering superior sealing followability.
Outstanding puncture and burst pressure resistance: The interwoven fiber structure provides high strength while remaining soft.
Good electrical insulation properties.
Asbestos-free, environmentally friendly, and safe.
Excellent flexibility and compression resilience: Effectively compensates for minor flange surface irregularities and displacement caused by thermal cycles, offering superior sealing followability.
Outstanding puncture and burst pressure resistance: The interwoven fiber structure provides high strength while remaining soft.
Good electrical insulation properties.
Asbestos-free, environmentally friendly, and safe.
Disadvantages:
Relatively limited high-temperature resistance: Continuous use temperature typically does not exceed 200°C (depending on the rubber binder).
Moderate resistance to strong acids, bases, and some polar solvents.
Mechanical rigidity is significantly lower than G10.
Relatively limited high-temperature resistance: Continuous use temperature typically does not exceed 200°C (depending on the rubber binder).
Moderate resistance to strong acids, bases, and some polar solvents.
Mechanical rigidity is significantly lower than G10.
Suitable Environments:
Medium- and low-pressure pipeline flanges, valves, pump casings, etc., where good sealing followability is required.
Suitable for media such as water, steam, air, hydraulic oil, oil, and gas.
Typical operating temperature range: -40°C to +200°C.
Medium- and low-pressure pipeline flanges, valves, pump casings, etc., where good sealing followability is required.
Suitable for media such as water, steam, air, hydraulic oil, oil, and gas.
Typical operating temperature range: -40°C to +200°C.
Gylon 3500 is a flexible insulating sealing material produced by Garlock (USA), based on 100% expanded polytetrafluoroethylene (ePTFE). It combines exceptional chemical inertness with electrical insulation properties.
Material: Pure ePTFE (unfilled)
Operating Temperature: -268°C to +260°C
Dielectric Constant (1 MHz): Approximately 2.1
Volume Resistivity: >1×10¹⁸ Ω·cm
Minimal water absorption, extremely low permeability
Operating Temperature: -268°C to +260°C
Dielectric Constant (1 MHz): Approximately 2.1
Volume Resistivity: >1×10¹⁸ Ω·cm
Minimal water absorption, extremely low permeability
Gylon 3500 Insulating Gasket 100% PTFE is the Base material, Operating Temperature: -268℃ to +260 ℃
Advantages:
Resistant to almost all chemicals (including strong acids, bases, organic solvents).
Exceptionally wide operating temperature range.
Ultra-high electrical insulation performance, suitable for high-frequency/high-voltage applications.
Soft and easy to install, conforms to uneven flange surfaces.
Resistant to almost all chemicals (including strong acids, bases, organic solvents).
Exceptionally wide operating temperature range.
Ultra-high electrical insulation performance, suitable for high-frequency/high-voltage applications.
Soft and easy to install, conforms to uneven flange surfaces.
Disadvantages:
Low mechanical strength, poor creep resistance, often requires use with a limiting ring.
High cost.
Not suitable for high-wear or high-shear applications.
Low mechanical strength, poor creep resistance, often requires use with a limiting ring.
High cost.
Not suitable for high-wear or high-shear applications.
Suitable Environments:
Sealing and insulation in extremely corrosive media, such as chlor-alkali industries and strong acid processing lines.
Industries with high purity requirements, such as semiconductors, biopharmaceuticals, and food processing.
Cryogenic applications, such as LNG (liquefied natural gas) facilities.
Critical connections requiring long service life, minimal maintenance, and reliable insulation.
Sealing and insulation in extremely corrosive media, such as chlor-alkali industries and strong acid processing lines.
Industries with high purity requirements, such as semiconductors, biopharmaceuticals, and food processing.
Cryogenic applications, such as LNG (liquefied natural gas) facilities.
Critical connections requiring long service life, minimal maintenance, and reliable insulation.
4. Klinger C4430 Insulating Gasket
Klinger C4430 is a compressed synthetic fiber gasket developed by the Austrian company Klinger, representing a new standard in non-asbestos sealing materials. It utilizes a blend of glass and synthetic fibers reinforced with an NBR (nitrile rubber) binder, forming a dense structure through a special compression process.
Klinger C4430 is a compressed synthetic fiber gasket developed by the Austrian company Klinger, representing a new standard in non-asbestos sealing materials. It utilizes a blend of glass and synthetic fibers reinforced with an NBR (nitrile rubber) binder, forming a dense structure through a special compression process.
Klinger C4430 Insulating Gasket Surface Treatment: Double-sided 3XA anti-adhesive coating, no need for lubricant during installation, easy to disassemble, Maximum liquid operating temperature 430℃， Maximum pressure 100 bar(10 MPa)
Key Performance Parameters:
Temperature/Pressure Limits: Maximum liquid operating temperature 430°C, maximum pressure 100 bar (10 MPa)
Surface Treatment: Dual-sided 3XA anti-stick coating, eliminating the need for installation lubricants and facilitating easy disassembly
Density: 1.7 g/cm³
Temperature/Pressure Limits: Maximum liquid operating temperature 430°C, maximum pressure 100 bar (10 MPa)
Surface Treatment: Dual-sided 3XA anti-stick coating, eliminating the need for installation lubricants and facilitating easy disassembly
Density: 1.7 g/cm³
Advantages:
First non-asbestos gasket to achieve CAF (Compressed Asbestos Fiber) performance: Successfully matches or exceeds the sealing performance of CAF after its phase-out.
Excellent chemical resistance: Suitable for air, water, saturated steam (up to 250°C), oils, fuels, and various gases; one of the most versatile gasket materials.
Outstanding performance in high-pressure steam: Certified by German DVGW and Australian AGA gas associations, reliable in pipeline systems up to 100 bar.
Easy installation and maintenance: The 3XA anti-stick coating eliminates gasket-to-flange adhesion, significantly reducing maintenance time and costs.
First non-asbestos gasket to achieve CAF (Compressed Asbestos Fiber) performance: Successfully matches or exceeds the sealing performance of CAF after its phase-out.
Excellent chemical resistance: Suitable for air, water, saturated steam (up to 250°C), oils, fuels, and various gases; one of the most versatile gasket materials.
Outstanding performance in high-pressure steam: Certified by German DVGW and Australian AGA gas associations, reliable in pipeline systems up to 100 bar.
Easy installation and maintenance: The 3XA anti-stick coating eliminates gasket-to-flange adhesion, significantly reducing maintenance time and costs.
Limitations:
Sensitive to thermal gradients: While peak temperature is 430°C, long-term operation above 300°C may result in up to 11% thickness loss, requiring regular torque checks on fasteners.
Limited in strongly oxidizing media: Not suitable for concentrated sulfuric acid, nitric acid, or certain polar solvents.
Sensitive to thermal gradients: While peak temperature is 430°C, long-term operation above 300°C may result in up to 11% thickness loss, requiring regular torque checks on fasteners.
Limited in strongly oxidizing media: Not suitable for concentrated sulfuric acid, nitric acid, or certain polar solvents.
Moderate electrical insulation: As a fiber-rubber composite, its insulation is far inferior to G10 or PTFE-based materials, making it unsuitable for high-voltage electrical isolation.
Cold flow characteristics: Exhibits minor plastic deformation under long-term high stress, necessitating periodic bolt retightening.
Cold flow characteristics: Exhibits minor plastic deformation under long-term high stress, necessitating periodic bolt retightening.
Suitable Environments
C4430 is a versatile all-rounder for industrial process sealing:
Energy Industry: Steam pipelines in thermal power plants, gas transmission systems, cogeneration equipment.
Chemical Sector: Refining units, chemical reactors, hydrocarbon medium transfer flanges (except strong oxidizers).
Utilities: Potable water systems (compliant with AS4020 & WRC standards), HVAC, compressed air networks.
Marine & Offshore: Certified by Lloyds Register, suitable for ship steam systems and fuel pipelines.
C4430 is a versatile all-rounder for industrial process sealing:
Energy Industry: Steam pipelines in thermal power plants, gas transmission systems, cogeneration equipment.
Chemical Sector: Refining units, chemical reactors, hydrocarbon medium transfer flanges (except strong oxidizers).
Utilities: Potable water systems (compliant with AS4020 & WRC standards), HVAC, compressed air networks.
Marine & Offshore: Certified by Lloyds Register, suitable for ship steam systems and fuel pipelines.
Qishine is ideal choice for EPC companies and project contractors.
Website: www.qishine.com
Email: qishine@qishine.com
Tel: 0592-5225595
Email: qishine@qishine.com
Tel: 0592-5225595
WhatsApp: +86 15960259563
Summary and Selection Guide
| Characteristic Dimension | G10 | Klinger C4430 | Klinger C4400 | Gylon 3500 |
| Core Advantage | Mechanical Strength + Insulation | High-Temp/High-Pressure Steam | Economical & Versatile | Chemical Inertness + Cryogenic |
| Max Temperature | 140°C | 430°C | 400°C | 260°C |
| Max Pressure | Design-Dependent | 100 bar | 100 bar | 83 bar |
| Electrical Insulation | ★★★★★ | ★★☆ | ★★☆ | ★★★★ |
| Chemical Resistance | ★★★ | ★★★★ | ★★★★ | ★★★★★ |
| Steam Suitability | Not Recommended | ★★★★★ | ★★★ | ★★★ |
| Cryogenic Performance | Risk of Embrittlement | Limited | Limited | ★★★★★ |
| Flame Retardance | HB Grade | Moderate | Moderate | Self-extinguishing |
| Typical Cost | Medium | Low | Low | High |
| Maintenance Ease | Requires Custom Machining | 3XA Coating, Excellent | 3XA Coating, Excellent | Excellent |
💡 Key Selection Points
Selecting an insulating gasket is essentially about finding the most suitable "isolation barrier" for specific operating conditions.
Consider the Medium: For highly corrosive environments, choose Gylon 3500; for water, steam, hydrocarbons, consider Klinger C4430/C4400; for general insulation, consider G10.
Consider Temperature & Pressure: For ultra-high temperature (>250°C) and high-pressure scenarios, Klinger C4400 is a reliable choice; for wide temperature ranges (especially low temperatures) and medium pressure, Gylon 3500 performs excellently.
Selecting an insulating gasket is essentially about finding the most suitable "isolation barrier" for specific operating conditions.
Consider the Medium: For highly corrosive environments, choose Gylon 3500; for water, steam, hydrocarbons, consider Klinger C4430/C4400; for general insulation, consider G10.
Consider Temperature & Pressure: For ultra-high temperature (>250°C) and high-pressure scenarios, Klinger C4400 is a reliable choice; for wide temperature ranges (especially low temperatures) and medium pressure, Gylon 3500 performs excellently.
Consider Flange Condition: For old, defective, or uneven flanges, Gylon 3500 offers better adaptability.
Consider Overall Cost: G10 offers the best cost-effectiveness; the Klinger series provides high return on investment in terms of durability and sealing; Gylon 3500 is irreplaceable in harsh corrosive environments.
Consider Overall Cost: G10 offers the best cost-effectiveness; the Klinger series provides high return on investment in terms of durability and sealing; Gylon 3500 is irreplaceable in harsh corrosive environments.
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