High-Performance Expanded Graphite Gaskets for Bulk OEM and Custom Manufacturing Solutions in China

What are Expanded Graphite Gaskets?

Expanded graphite gaskets are high-performance sealing components manufactured from exfoliated or expanded graphite foil. This material is created by treating natural graphite with acid and heat, causing it to expand into a low-density, vermiform structure. The resulting foil is then calendered and can be reinforced or used in pure form to create gaskets. These seals are renowned for their exceptional thermal stability, chemical resistance, and reliable sealing performance under extreme conditions, making them a superior choice over traditional materials like compressed non-asbestos (CNA) or PTFE in demanding applications.

At Kaxite Seals, we specialize in engineering expanded graphite gaskets that meet the rigorous demands of modern industry. Our product line is designed to provide a leak-free seal in systems involving high temperatures, aggressive media, and fluctuating pressures, ensuring operational safety, efficiency, and longevity.

Key Features and Benefits of Kaxite Expanded Graphite Gaskets

The superiority of our expanded graphite gaskets stems from the intrinsic properties of the material and our precise manufacturing process. Below are the core features and the direct benefits they deliver:

• Extreme Temperature Resistance: Capable of continuous operation from cryogenic temperatures up to 3000°F (1650°C) in non-oxidizing atmospheres, and up to 900°F (482°C) in oxidizing environments. This prevents seal degradation and failure in furnaces, exhaust systems, and high-temperature piping.
• Excellent Chemical Resistance: Inert to most chemicals, solvents, acids, and alkalis (except strong oxidizing agents). This ensures seal integrity in chemical processing, petrochemical, and pharmaceutical applications.
• Superior Sealability & Low Creep Relaxation: The soft, conformable nature of expanded graphite allows it to seat into minor flange imperfections, creating an excellent initial seal. It exhibits minimal creep relaxation under bolt load, maintaining sealing force over long periods.
• Thermal & Electrical Conductivity: Graphite is both a good conductor of heat and electricity, which can be beneficial for heat dissipation and in applications requiring electrical grounding across the flange.
• No Asbestos, Environmentally Friendly: Kaxite gaskets are 100% asbestos-free, making them a safe and sustainable sealing solution compliant with global environmental and safety regulations.
• Flexibility & Easy Installation: The material is flexible and easy to handle, cut, and install, reducing installation time and the risk of handling damage.

Technical Specifications & Product Parameters

To specify the correct expanded graphite gasket for your application, please refer to the following detailed technical data for standard Kaxite Seals products. Custom specifications are available upon request.

Material Properties Table

Standard Product Range

• Pure Expanded Graphite Foil Gaskets: Unreinforced, soft gaskets for standard flanges (ASME B16.21, DIN, EN).
• Reinforced Graphite Gaskets: Laminated with stainless steel insert (tanged or perforated core) or foil facing for enhanced handling strength and blow-out resistance.
• Corrugated/Profile Gaskets: Graphite foil with a corrugated metal core for high-pressure applications.
• Spiral Wound Gaskets with Graphite Filler: For ASME B16.20 / B16.21, featuring expanded graphite as the filler material for high-temperature service.
• Kammprofile Gaskets: Metal core with serrated faces and expanded graphite layers on both sides, offering excellent performance under thermal cycling.
• Custom Shapes & Sizes: Die-cut, laser-cut, or waterjet-cut to match any flange geometry, including heat exchanger, valve, and pump applications.

Applications of Expanded Graphite Gaskets

Kaxite expanded graphite gaskets are deployed across a wide spectrum of industries where reliability under stress is non-negotiable.

• Power Generation: Gas turbine exhausts, heat recovery steam generators (HRSG), boiler manways, and high-temperature steam lines.
• Petrochemical & Refining: Reactors, reformers, cracker units, heat exchangers, and flanges handling hot oils, gases, and hydrocarbons.
• Chemical Processing: Vessels, columns, and piping for aggressive acids, alkalis, and solvents (excluding strong oxidizers like nitric acid).
• Heating & Thermal Processing: Furnace doors, annealing lines, incinerators, and any high-temperature industrial heating equipment.
• Automotive & Aerospace: Exhaust systems, turbocharger connections, and engine test stands.
• General Industrial: Hot water, steam, and thermal fluid systems.

Frequently Asked Questions (FAQ) About Expanded Graphite Gaskets

General Questions

Q: What is the primary advantage of expanded graphite over compressed non-asbestos (CNA) gaskets?

A: The primary advantages are significantly higher temperature resistance and lower creep relaxation. While CNA gaskets are typically limited to about 400°C (750°F), expanded graphite can function reliably up to 500°C in air and far beyond in inert atmospheres. It also maintains bolt load better, reducing the need for retorquing and preventing leaks over time.

Q: Can expanded graphite gaskets be used with strong oxidizing acids?

A: No, this is a critical limitation. Strong oxidizing agents such as concentrated nitric acid, sulfuric acid above 98%, and halogens (like chlorine gas) will aggressively attack and oxidize the graphite, leading to rapid seal failure. For these media, PTFE-based gaskets are recommended.

Q: Are Kaxite expanded graphite gaskets suitable for high-pressure applications?

A: Pure expanded graphite foil has moderate blow-out resistance. For high-pressure applications, we strongly recommend our reinforced versions, such as tanged metal insert graphite gaskets, corrugated metal core gaskets, or spiral wound gaskets with graphite filler. These designs incorporate a metal structure to contain the graphite and resist high internal pressures.

Installation & Handling

Q: How should I store and handle expanded graphite gaskets?

A: Store gaskets in a cool, dry place away from direct sunlight and moisture. Keep them in their original packaging until use. Handle them with clean hands or gloves to avoid contamination from oils or dirt. While flexible, they should not be bent or folded sharply, as this can cause cracking, especially in pure foil grades.

Q: What is the recommended flange surface finish for an expanded graphite gasket?

A: A serrated finish (such as a concentric or phonographic serration) with a roughness average (Ra) between 3.2 and 6.3 micrometers (125-250 microinches) is ideal. This provides enough "bite" for the soft graphite to flow into, creating a secure seal without causing excessive wear on the gasket. Smooth, mirror-finish flanges are not recommended.

Q: Do I need to use a sealant or lubricant on an expanded graphite gasket?

A: Absolutely not. Expanded graphite gaskets are self-sealing and should be installed clean and dry on clean, dry flanges. Applying a sealant can contaminate the graphite, hinder its conformability, cause chemical incompatibility, and potentially lead to leakage. The only exception might be a very light application of an anti-stick agent like molybdenum disulfide powder on the flange face for extremely high-temperature services to prevent adhesion, but this is not standard practice.

Performance & Selection

Q: How do I choose between pure foil and reinforced expanded graphite gaskets?

A: Use pure expanded graphite foil for standard flat-face or raised-face flanges in low to medium-pressure applications with excellent temperature and chemical resistance. Choose a reinforced gasket (with metal insert or facing) when you need improved handling strength, higher blow-out resistance for larger sizes or higher pressures, or dimensional stability for complex geometries.

Q: Can expanded graphite gaskets be reused after disassembly?

A: It is generally not recommended. Once compressed during installation, the graphite's structure has deformed to match the specific flange surface. Upon disassembly, this "set" is permanent, and the gasket will have lost a portion of its original thickness and recovery properties. Reusing it is unlikely to provide a reliable, leak-tight seal. For critical applications, always install a new gasket.

Q: What makes Kaxite Seals' expanded graphite different from other brands?

A: Kaxite Seals utilizes premium-grade, high-purity natural graphite with consistent exfoliation and calendering processes, resulting in a foil with uniform density and superior mechanical properties. Our quality control ensures low chloride and sulfur content, which is vital for preventing corrosion on stainless steel flanges. Furthermore, our technical support team assists with material selection and design to guarantee optimal performance for your specific application.

Ordering Information & Custom Solutions from Kaxite Seals

Selecting the right gasket is crucial for system integrity. When ordering, please provide the following information to ensure you receive the correct Kaxite product:

• Flange standard and type (e.g., ASME B16.5, Class 150, RF).
• Nominal pipe size and flange dimensions (OD, ID, thickness).
• Operating temperature (min/max).
• Media being sealed (full chemical name/concentration if possible).
• Operating pressure.
• Preferred gasket type (pure foil, reinforced, spiral wound, etc.).

Our engineering team is equipped to develop custom expanded graphite sealing solutions for unique challenges, including irregular shapes, special composite constructions, and applications with combined stresses.