A: For steam systems operating below 250 psi, graphite gaskets with stainless steel reinforcement are an excellent choice. Graphite offers high thermal stability and chemical resistance, while the stainless reinforcement enhances mechanical strength and blowout resistance. These gaskets maintain their integrity at elevated temperatures and can conform well to flange irregularities, making them suitable for demanding industrial environments such as power plants, chemical processing, and refineries.

A: Typically, metal gaskets are not reusable unless specifically designed for that purpose, such as certain ring-type joints (RTJs). Reusing a gasket can compromise the seal due to deformation during the initial installation. Always inspect for damage, compression loss, or surface imperfections, and replace as necessary to avoid costly leaks or failures.

1. Primary Function

• Gaskets:

  • Static seals (used between non-moving surfaces).

  • Prevent leaks in flat connections (e.g., pipe flanges, tank lids, machinery housings).

  • Compressed between two surfaces to block fluids or gases.

• Seals:

  • Dynamic or static seals (used in both moving and stationary parts).

  • Prevent leaks in rotating or sliding components (e.g., pump shafts, hydraulic pistons).

  • Designed to handle motion while maintaining a tight barrier.

2. Common Applications

3. Design & Material Differences

4. Movement & Pressure Handling

• Gaskets:

  • Only for static applications (no movement).

  • Can fail if surfaces shift or compression is uneven.

• Seals:

  • Dynamic seals handle rotation, sliding, or reciprocating motion.

  • Must resist wear while maintaining contact.

5. Failure Modes

• Gaskets:

  • Blowouts, compression set, chemical swelling.

  • Fails if surfaces are misaligned or bolts loosen.

• Seals:

  • Wear from friction, hardening, or extrusion.

  • Fails if lubricant dries up or seal lip gets damaged.

Key Takeaway:

• Gaskets = Stationary sealing (flat surfaces, no motion).

• Seals = Motion sealing (rotating/sliding parts) or specialized static fits (O-rings).

A: For hygienic processing, FDA-compliant PTFE (Teflon) or white EPDM gaskets are commonly used. These materials are non-toxic, resistant to cleaning agents, and suitable for steam sterilization. Ensure the material meets 3-A Sanitary Standards or USP Class VI if required.

A: Use a chemical compatibility chart to match gasket materials to the media they will contact. PTFE, Viton, and expanded graphite offer strong resistance to aggressive chemicals. Always verify compatibility at the application’s temperature and pressure to avoid degradation or swelling.

A: Spiral wound gaskets use a mix of metal windings and filler (typically graphite or PTFE) and are ideal for high-pressure, high-temperature applications. Kammprofile gaskets have a metal core with serrated grooves and a soft facing—offering superior sealing, especially on flanges with poor surface finish. Kammprofiles are also reusable in some cases.

A: Torque values depend on gasket type, flange size, bolt grade, and lubrication. Always follow the manufacturer’s torque chart. Over- or under-tightening is a major cause of gasket failure. Use a calibrated torque wrench and consider a cross-bolt pattern for even load distribution.

A: Common causes include:

• Over-compression or under-torque
• Thermal cycling causing expansion/contraction
• Incorrect material selection
• Improper installation or flange misalignment

Prevention includes proper training, torque verification, and quality gasket materials.

A: For flue gas or exhaust systems with temperatures over 500°C (930°F), use flexible graphite or mica-based gaskets. They maintain integrity at high temperatures and resist oxidation. Avoid rubber or elastomeric materials—they break down quickly under such conditions.

A: As a rule of thumb, replace gaskets anytime a joint is broken. Even if the gasket appears intact, its ability to reseal is reduced. For critical applications, follow a predictive maintenance schedule based on hours of operation, media type, and temperature cycles.

A: Yes. Some manufacturers now offer biodegradable or non-toxic gasketing materials, such as vegetable fiber, cork rubber, and low-VOC elastomers. These are suitable for specific low-pressure applications and industries seeking greener alternatives. Always balance performance and environmental goals.