What are Spiral Wound Gaskets?

Spiral wound gaskets are fundamental sealing components used in a vast array of industrial piping and pressure vessel applications. Engineered for resilience and adaptability, they are constructed by winding a pre-formed metal strip and a softer filler material (like graphite, PTFE, or ceramic) in a V-shaped spiral around a solid metal outer ring (and sometimes an inner ring). This unique construction creates a robust, semi-metallic seal that combines the spring-like recovery of the metal with the conformability and sealing properties of the filler. This design makes them exceptionally reliable for sealing flanged connections under high pressure, high temperature, and variable thermal cycling conditions, preventing leaks of fluids and gases in critical systems.

Key Features and Advantages

The widespread use of spiral wound gaskets is attributed to their distinct advantages over other gasket types. Their primary strength lies in their ability to maintain a seal under challenging conditions where other gaskets might fail.

• Excellent Resilience and Recovery: The spiral-wound, layered structure acts like a spring, allowing the gasket to compensate for flange rotation, slight misalignment, and thermal expansion/contraction of the bolted connection.
• Wide Temperature and Pressure Range: By selecting appropriate metal and filler combinations, these gaskets can perform reliably from cryogenic temperatures up to approximately 1000°C (1832°F) and from vacuum conditions to extremely high pressures.
• Superior Creep Relaxation Resistance: The metal winding provides superior resistance to the loss of bolt load over time (creep relaxation), ensuring a lasting seal throughout the maintenance cycle.
• High Blowout Resistance: The metallic structure provides significant strength, preventing the gasket from being extruded or blown out under sudden pressure surges.
• Versatility: Available in a multitude of standard and custom sizes, materials, and facing options to suit virtually any application, including ASME B16.20, API 6A, and DIN standards.

In-Depth Product Specifications of Kaxite Sealing Spiral Wound Gaskets

At Kaxite Sealing, we manufacture spiral wound gaskets to the highest international standards, ensuring precision, reliability, and safety. Our product specifications are detailed below to guide your selection.

Standard Construction & Dimensions

Our standard gaskets comply with ASME B16.20 and API 6A specifications for raised face (RF) and ring-type joint (RTJ) flanges. Custom designs for flat face (FF) and male-female (M/F) flanges are also available.

Material Combinations

The performance of a spiral wound gasket is defined by its material pairing. Kaxite Sealing offers a comprehensive selection to meet specific media, temperature, and pressure requirements.

Filler Material Properties

• Flexible Graphite (Grafoil®): Excellent thermal and chemical resistance, low creep relaxation, performs in oxidizing atmospheres up to 450°C, non-stick properties.
• PTFE (Teflon®): Superior chemical inertness, low friction, excellent for corrosive media and clean systems. Temperature limited compared to graphite.
• Ceramic / Mica / Non-Asbestos Fillers: Used for extremely high-temperature applications (exceeding 500°C) where graphite may oxidize. Provides good thermal and electrical insulation.

Frequently Asked Questions (FAQ) About Spiral Wound Gaskets

Q: When should I use a spiral wound gasket instead of a flat gasket?

A: Spiral wound gaskets are the preferred choice for medium to high-pressure applications (typically above Class 150/PN20), high-temperature services, and systems with significant thermal cycling or potential for flange movement. They are also recommended for critical service involving hazardous, toxic, or expensive media where leak-tight integrity is paramount. For low-pressure, low-temperature, and non-critical applications with smooth flanges, simpler flat gaskets (e.g., rubber, compressed non-asbestos) may be sufficient and more cost-effective.

Q: What is the purpose of the inner and outer rings on a spiral wound gasket?

A: The outer ring (centering ring) serves multiple functions: it centers the gasket correctly within the bolt circle, provides radial stability during handling and installation, acts as a compression stop to prevent over-compression of the winding, and offers some blow-out protection. The inner ring is optional but highly recommended for specific services. Its primary roles are to prevent inward buckling of the winding under high internal pressure, improve gasket stability in vacuum service, and protect the soft filler from being eroded by turbulent or high-velocity media flowing through the pipe.

Q: How do I select the correct metal and filler material for my application?

A: Material selection is critical and depends on three main factors: the chemical compatibility with the medium being sealed, the operating temperature, and the system pressure. First, consult chemical compatibility charts for both the metal and filler against your process fluid. Second, ensure both materials can withstand the continuous and peak temperatures of your system. Finally, verify that the chosen metal winding has sufficient mechanical strength for the flange pressure class. Consulting the Kaxite Sealing engineering team with your specific service conditions is the best practice for optimal selection.

Q: Can spiral wound gaskets be reused?

A: It is generally not recommended to reuse spiral wound gaskets. During the initial bolting, the gasket is compressed to a specific design thickness, and the filler material flows to create a seal. Upon disassembly, the gasket does not fully recover to its original thickness, and the filler material's sealing properties are compromised. Reusing an old gasket significantly increases the risk of a leak. For reliable performance and safety, always install a new, unused gasket from a trusted supplier like Kaxite Sealing during any flange reassembly.

Q: How do I properly install and torque a spiral wound gasket?

A: Proper installation is key to achieving a leak-free seal. First, ensure flanges are clean, undamaged, and aligned. Place the gasket carefully onto the centering ring. Use lubricated bolts and nuts of the correct grade. Follow a cross-pattern (star pattern) bolting sequence in multiple passes to ensure even compression. The final torque value is crucial and must adhere to the flange standard (e.g., ASME PCC-1) or the equipment manufacturer's specification, taking into account bolt lubrication. Under-torquing can cause leaks; over-torquing can crush the gasket windings, damaging its sealing ability.

Q: What certifications do Kaxite Sealing spiral wound gaskets carry?

A: Kaxite Sealing is committed to quality and safety. Our manufacturing process and products can be supplied with relevant certifications as required, including material traceability to Mill Test Certificates (MTCs/CMTRs). We can provide gaskets compliant with NACE MR0175/MR0103 for sour service (H2S environments). Our quality management system is designed to meet industry demands, and specific third-party certifications (e.g., API, CE PED) can be discussed based on project requirements.