Dec 2, 2024
What is a spiral wound gasket, and why is it essential in critical sealing applications? Spiral wound gaskets are advanced sealing components engineered to create a reliable seal between two flange surfaces, even under extreme temperature and pressure conditions. These gaskets play a critical role in industries where fluid or gas containment integrity is paramount, such as oil and gas, chemical processing, power generation, and petrochemical applications. What sets them apart in demanding environments is their unique construction and versatility.
Types of Spiral Wound Gaskets
Spiral wound gaskets come in several variations to meet specific application requirements. Each type is designed with unique features to address diverse operational demands:
- Basic Type (Style R)
Style R gaskets are standard spiral wound gaskets without inner or outer rings. They are best suited for tongue-and-groove or male-and-female flange configurations, where precise centering is less critical. These gaskets perform effectively in low-pressure and low-stress conditions. - Outer Ring Type (Style CGI)
Style CGI gaskets are equipped with an outer centering ring, making them ideal for raised face flanges. The centering ring aids in proper alignment and protects the gasket from blowout. Additionally, it prevents over-compression, enhancing durability in higher pressure and temperature environments. - Customized Variants
Custom spiral wound gaskets can be tailored using specific materials and construction techniques to meet unique operational needs or industry standards. - SWG Style D
This variant features a sealing element made of preformed engineered metal and a compressible filler material. It is typically used in tongue-and-groove or male-and-female flanges. When equipped with an inner ring (Style DI), it offers additional structural support and enhanced resistance to blowout.
Selecting the appropriate spiral wound gasket requires a thorough understanding of the operating pressure, temperature, and chemical compatibility for the intended application.
Spiral Wound Gasket Construction
The intricate construction of spiral wound gaskets is key to their performance in extreme conditions. They are manufactured by winding alternating layers of metal and filler material in a spiral pattern, which provides strength and sealing capability.
- Metal Winding
The metal strip, often made of stainless steel, Inconel, or other alloys, provides structural integrity and resilience. The choice of metal depends on the application’s specific temperature, pressure, and chemical resistance requirements. - Filler Material
Materials like graphite or PTFE are used as fillers to enhance sealing performance. Graphite is ideal for high-temperature applications, while PTFE excels in corrosive chemical environments. - Inner and Outer Rings
Inner rings prevent the inward buckling of the gasket and ensure better structural support in high-pressure applications. Outer rings facilitate proper alignment and protect against over-compression. Together, these rings reinforce the gasket and ensure reliable sealing under demanding conditions.
This meticulous construction enables spiral wound gaskets to accommodate flange imperfections and maintain an effective seal, even during temperature and pressure fluctuations.
Spiral Wound Gasket vs. Alternative Gasket Types
When selecting the appropriate sealing solution, it’s essential to compare spiral wound gaskets with other common gasket types to ensure compatibility with the application’s pressure, temperature, and media requirements.
Spiral Wound Gaskets vs. Kammprofile Gaskets
Kammprofile gaskets consist of a solid metal core with serrated grooves and a soft sealing layer, typically made of graphite or PTFE. While both are suitable for high-pressure and high-temperature environments, spiral wound gaskets offer greater flexibility and recovery, making them more suitable for applications where flange movement or vibration is expected. In contrast, Kammprofile gaskets provide a more stable seal where flange rotation or gasket blow-out is a concern.
Spiral Wound Gaskets vs. Ring-Type Joint (RTJ) Gaskets
RTJ gaskets are typically used in high-pressure applications such as oil and gas pipelines and offshore platforms. These solid metal gaskets fit into specially grooved flanges and provide a very tight seal. However, they lack the flexibility and recovery characteristics of spiral wound gaskets, which can accommodate minor flange imperfections and thermal cycling better.
Spiral Wound Gaskets vs. Sheet Gaskets (Compressed Fibre or PTFE)
Sheet gaskets are economical and used in less demanding applications. They are easier to cut and install but lack the sealing performance and durability of spiral wound gaskets in high-pressure or high-temperature environments. Spiral wound gaskets are preferred when sealing reliability, chemical compatibility, and mechanical resilience are critical.
Summary Table:
| Gasket Type | Temperature & Pressure | Recovery | Ideal For |
|---|---|---|---|
| Spiral Wound | High | High | Dynamic loads, thermal cycling |
| Kammprofile | High | Moderate | Stable loads, limited flange movement |
| Ring-Type Joint (RTJ) | Very High | Low | Extreme pressures, grooved flanges |
| Sheet Gaskets (PTFE/CNAF) | Low to Moderate | Low | General-purpose, low-severity applications |
Choosing the right gasket type depends on factors such as system pressure, media, flange condition, and regulatory requirements. Durlon’s technical team can assist in evaluating the most suitable sealing option for your application.
Spiral Wound Colors
Spiral wound gaskets are often color-coded according to international standards to identify their material composition, pressure ratings, and specific features. This visual identification simplifies the selection process and enhances safety during installation and maintenance.
Color Coding According to ASME B16.20 / API Standards:
Function of the Color Codes:
- Outer Ring Color (Metallurgy): Indicates the metal winding or ring material, helping technicians quickly verify compatibility with service conditions (e.g., chemical resistance, corrosion).
- Filler Color: Identifies the soft filler material, essential for assessing temperature and media suitability.
Best Practices:
- Always confirm color codes with documentation or the gasket manufacturer before installation.
- Never rely solely on color for specification; verify material certification for high-risk applications.
- If a gasket is customized, ensure custom markings are clearly indicated in line with plant procedures.
Durlon spiral wound gaskets follow industry-standard color codes and are clearly marked to prevent installation errors. We also offer product customization with traceability and documentation for critical service environments.
When to Use a Spiral Wound Gasket
Spiral wound gaskets are indispensable in situations requiring high performance and reliability. They are most effective in:
- High-Pressure Environments: Suitable for pressures up to 250 bar or higher, making them ideal for applications like natural gas pipelines or high-pressure steam systems.
- Temperature Extremes: Capable of withstanding temperatures ranging from cryogenic levels to over 1000°C, they are essential for power generation and petrochemical processing.
- Critical Applications: Industries handling hazardous or toxic materials rely on these gaskets to prevent leaks and ensure compliance with safety and environmental regulations.
Common Mistakes When Changing a Spiral Wound Gasket
Proper installation and maintenance are critical to ensure optimal gasket performance. Avoid these common mistakes:
- Incorrect Gasket Selection: Always verify chemical compatibility, temperature, and pressure ratings to ensure the gasket matches the application requirements.
- Uneven Bolt Tightening: Uneven torque can lead to leaks or over-compression. Use a torque wrench and follow the recommended bolt-tightening sequence for even pressure distribution.
- Damaged or Dirty Flange Surfaces: Clean and inspect flange faces to remove debris or damage that could compromise the seal.
- Reusing Old Gaskets: Spiral wound gaskets lose their elasticity after compression and should never be reused.
- Over-Compression: Exceeding the specified torque values can deform the gasket, reducing its sealing capability.
Superior Spiral Wound Gasket Solutions
Spiral wound gaskets excel in meeting the demands of challenging operational conditions, ensuring safety and efficiency in critical applications.
At Durlon, we specialize in high-performance spiral wound gaskets designed for industrial environments. Our products combine durability, precision, and superior sealing capabilities to meet the most stringent standards. Backed by over 40 years of sealing expertise and ISO 9001 certification, we provide solutions that reduce fugitive emissions, extend equipment life, and deliver reliable performance in critical service.
If you’re asking what a spiral wound gasket is and how it applies to your operation, our team of technical experts can help. Contact Durlon today for expert guidance, product recommendations, or a customized sealing solution to optimize performance and safety in your application.