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Frequently Asked Questions (FAQ) About Graphite Sheets

Q: What is the primary difference between a compressed asbestos fiber (CAF) gasket and a graphite sheet gasket?

A: The differences are substantial. CAF gaskets are composite materials containing asbestos fibers, which pose significant health risks and are banned or restricted in many regions. They have lower temperature limits (typically up to 1000°F / 538°C for some grades) and can be prone to embrittlement. Kaxite Sealing graphite sheets are made from pure, exfoliated graphite. They are asbestos-free, safer to handle, offer higher temperature resistance (up to 3000°F / 1650°C inert), provide better chemical resistance, superior conformability, and excellent thermal conductivity, which CAF lacks. Graphite sheets also require lower seating stress to achieve an effective seal.

Q: Can graphite sheet gaskets be used for all types of fluids and chemicals?

A: Kaxite Sealing graphite sheets exhibit excellent resistance to a vast array of media, including hot concentrated acids, alkalis, solvents, hydrocarbons, and steam. However, they are not universally compatible. Strong oxidizing agents at high concentrations and temperatures (e.g., fuming nitric acid, concentrated sulfuric acid above certain temperatures) can attack graphite. It is always recommended to consult Kaxite Sealing's chemical resistance guide or our engineering team for specific media compatibility, especially for critical or novel applications.

Q: How do I choose between a standard graphite sheet and a reinforced one?

A: The choice depends on your application's mechanical and pressure demands. Use standard flexible graphite sheets (like our KSG-1000) for general sealing on standard pipe flanges, heat exchangers, and valve bonnets where pressures are moderate, and handling is straightforward. Choose a reinforced graphite sheet (like our KSG-2000R) when you need extra mechanical strength for handling large gaskets, require high blow-out resistance for pressures exceeding 300 PSI, are dealing with large diameter or uneven flanges, or need dimensional stability in applications with severe thermal cycling. The metal insert provides a mechanical backbone.

Q: What is the proper installation procedure for a graphite sheet gasket?

A: Correct installation is key to performance. First, ensure both flange faces are clean, dry, and free of old gasket material and debris. The surface finish should ideally be between 125 and 500 µin Ra. Place the graphite gasket centered on the flange. Use a crisscross bolt tightening pattern (torque sequence) in multiple incremental steps to achieve the final recommended bolt load. This ensures even compression of the gasket across the entire flange. Do not over-torque, as this can crush and damage the graphite sheet. Refer to Kaxite Sealing's installation guide or the ASME PCC-1 standard for detailed best practices. Using a calibrated torque wrench is essential.

Q: Why is low chloride content important in a graphite sheet?

A: Low chloride content (typically specified as <50 ppm) is critical when sealing stainless steel, duplex, or other chloride-sensitive alloy flanges. In the presence of moisture and stress, chlorides can induce Stress Corrosion Cracking (SCC), a catastrophic and sudden failure mode. Kaxite Sealing rigorously controls raw material purity and manufacturing processes to ensure our graphite sheets meet the low chloride requirements for use in pharmaceutical, food processing, marine, and chemical industry applications where stainless steel is prevalent.

Q: Can graphite sheets be used as a thermal interface material (TIM) in electronics?

A: Absolutely. The high in-plane thermal conductivity of graphite sheets makes them exceptional thermal spreaders. They are used to dissipate heat from high-power components like CPUs, GPUs, LEDs, and power transistors. For TIM applications, Kaxite Sealing often supplies thin graphite sheets (0.1mm to 0.5mm) with pressure-sensitive adhesive (PSA) on one or both sides for easy attachment to heatsinks and components. They are lightweight, conformable, and offer more efficient heat spreading compared to many traditional gap pads, especially in space-constrained designs.

Q: How do I store and handle Kaxite Sealing graphite sheets?

A: Store sheets or gaskets in their original packaging in a cool, dry, and clean environment. Avoid exposure to moisture, dust, and direct sunlight. While graphite is robust, the sheets can be bent or creased, so handle them carefully, especially large, thin sheets. Use clean gloves to prevent contamination from skin oils. For reinforced sheets, be mindful of the metal edges. If a sheet becomes contaminated, it can often be cleaned with a solvent like isopropyl alcohol, but consult our handling guide first.