Find Bulk Expanded Graphite Gaskets Solutions from China Manufacturers for Wholesale

Expanded graphite gaskets, also known as flexible graphite gaskets, are high-performance sealing solutions engineered for demanding industrial applications. Manufactured from pure exfoliated graphite without the addition of binders or fillers, these gaskets offer exceptional thermal stability, chemical resistance, and reliable sealing under extreme conditions. At Kaxite, we specialize in producing premium expanded graphite gaskets that meet the rigorous standards of industries such as chemical processing, power generation, oil & gas, and refining.

What Are Expanded Graphite Gaskets?

Expanded graphite gaskets are created through a process where natural graphite flakes are treated with intercalation acids and then rapidly heated. This process, called exfoliation, causes the graphite layers to expand significantly, forming a vermiform or worm-like structure. This material is then calendered into sheets of pure, flexible graphite. These sheets can be cut, stamped, or molded into various gasket shapes. The resulting gasket material is inherently resilient, self-lubricating, and capable of conforming to uneven flange surfaces, creating a tight, long-lasting seal.

Key Product Parameters and Specifications

Kaxite expanded graphite gaskets are defined by a set of critical parameters that ensure their performance. Below is a detailed breakdown of our standard specifications.

Material Properties

• Base Material: 99% Pure Exfoliated (Expanded) Graphite
• Binder Content: None (Binder-Free)
• Color: Dark Gray to Black
• Density: Ranging from 0.7 g/cm³ to 1.3 g/cm³ (customizable)
• Temperature Resistance: From -240°C (-400°F) in inert atmospheres to 450°C (842°F) in oxidizing atmospheres. Up to 3000°C (5432°F) in non-oxidizing/reducing atmospheres.
• pH Range: 0 - 14 (Excellent resistance to most acids, alkalis, and solvents)
• Thermal Conductivity: High, both through-plane and in-plane.
• Compressibility: High (typically 40-60%)
• Recovery: Excellent (typically 15-25%)
• Creep Relaxation: Low

Standard Physical & Mechanical Properties Table

Available Forms and Styles from Kaxite

• Plain Sheets: Available in rolls and sheets of various thicknesses (0.4mm to 3.0mm).
• Die-Cut Gaskets: Precision-cut to customer-provided drawings or samples (ASME B16.21, DIN, JIS, etc.).
• Ring Gaskets (Kammprofile Filled): Expanded graphite filler in a grooved metal core for high-pressure applications.
• Spiral Wound Gaskets Filler: Used as the filler material in spiral wound gaskets for petrochemical services.
• Corrugated/Embossed Graphite: Enhanced seating and sealing performance for low-load flanges.
• Laminated Gaskets: Graphite laminated with stainless steel, tanged metal, or PTFE for added strength and handling.

Frequently Asked Questions (FAQ) About Expanded Graphite Gaskets

Q: What are the primary advantages of using expanded graphite gaskets over traditional asbestos or compressed non-asbestos (CNAF) gaskets?

A: Expanded graphite gaskets offer several key advantages. They are completely asbestos-free, ensuring safety and regulatory compliance. They provide superior thermal conductivity, allowing for more even heat distribution across the flange. Their chemical resistance is broader than many CNAF materials, especially against acids and bases. They exhibit excellent compressibility and recovery, leading to a reliable seal even under thermal cycling and low flange loads. Finally, they have a much wider temperature range, particularly on the high end in non-oxidizing environments.

Q: Can Kaxite expanded graphite gaskets be used for sealing oxygen or strong oxidizing agents?

A: Caution is required. While pure graphite is generally inert, under high-pressure oxygen or with powerful oxidizing agents (e.g., concentrated nitric acid, chlorine trifluoride) at elevated temperatures, oxidation reactions can occur. For such services, we recommend consulting with Kaxite engineering. We often suggest alternative materials like PTFE or specially treated, oxidation-inhibited graphite grades for these critical applications.

Q: How do I select the correct density for my application?

A: Density selection is crucial. Lower density graphite (e.g., 0.7-0.9 g/cm³) is softer, more conformable, and ideal for flanges with low bolting load, uneven surfaces, or low-pressure services. Standard density (1.0-1.1 g/cm³) offers a good balance of conformability and strength for most general applications. Higher density graphite (1.2-1.3 g/cm³) provides greater mechanical strength, reduced creep relaxation, and is recommended for high-pressure services, spiral wound gasket fillers, and applications involving high cycle fatigue.

Q: Are there any handling or installation precautions for graphite gaskets?

A: Yes. While robust in service, expanded graphite is relatively soft and can be damaged during handling. Avoid dragging gaskets over sharp edges or threaded bolts. It is also electrically conductive, so care should be taken in environments where short-circuiting is a risk. During installation, ensure flanges are clean, aligned, and free of old gasket material. Use a criss-cross bolting pattern and torque in multiple stages to the specified value to ensure even compression. Do not over-torque, as this can cause excessive creep and seal failure.

Q: What flange surface finish is recommended for optimal sealing with expanded graphite?

A: A serrated (phonographic) spiral finish, typically between 125 and 250 microinches Ra (3.2 to 6.3 µm Ra), is ideal. This finish provides enough "bite" for the graphite to flow into and create an effective seal without causing excessive wear or making gasket removal difficult. Smooth machined finishes (below 63 µin Ra) are not recommended as they may not provide sufficient grip. Excessively rough finishes can lead to high gasket blow-out and difficulty in achieving a seal.

Q: Can Kaxite provide expanded graphite gaskets with special features, like anti-adhesive coatings or metal inserts?

A: Absolutely. Kaxite offers a range of enhanced graphite products. We can apply anti-stick coatings (e.g., PTFE, ceramic) to one or both sides to prevent adherence to flanges, easing maintenance. We produce graphite sheets laminated with thin stainless steel foils (tanged or perforated) for improved handling and structural integrity. We also manufacture fully encapsulated gaskets, where the graphite is enclosed in a metal jacket (usually stainless steel) for services with severe thermal cycling or to prevent graphite erosion in high-velocity fluids.

Q: How do expanded graphite gaskets perform regarding fugitive emission standards?

A: Expanded graphite gaskets are an excellent choice for fugitive emission control due to their low permeability and high recovery. When tested according to standards like API 6AF/6FB or ISO 15848, properly installed Kaxite graphite gaskets consistently achieve very low leakage rates, often qualifying for "low emission" classifications. Their resilience helps maintain seal integrity during temperature and pressure transients, which is critical for long-term emission compliance.