In the demanding world of industrial sealing, where pressure, temperature, and media compatibility are non-negotiable factors, one solution consistently stands out for its reliability and versatility: Spiral Wound Gaskets. At Kaxite, we have dedicated decades to perfecting the engineering and manufacture of these critical components, understanding that the integrity of a flange connection can define the safety and efficiency of an entire operation. A spiral wound gasket is not merely a piece of equipment; it is a precisely engineered system designed to create a leak-proof seal in the most challenging environments, from high-pressure steam lines in power generation to corrosive chemical processing pipelines.
The core principle behind a spiral wound gasket is its unique composite structure. It is constructed by winding a pre-formed metal strip (the winding) and a soft filler material in a spiral, or helical, pattern around a solid metal inner ring. This winding process creates a resilient, spring-like structure with multiple concentric sealing points. Under bolt load, the metal windings provide structural strength and recovery, while the softer filler material flows into the micro-imperfections of the flange faces, creating an effective initial seal. This combination allows it to handle system fluctuations—thermal cycling, pressure spikes, and vibration—far better than many static gasket types. Kaxite's manufacturing rigor ensures each gasket delivers predictable, consistent performance, batch after batch.
Selecting the correct spiral wound gasket requires a detailed understanding of its construction and specifications. Kaxite gaskets are manufactured to meet and exceed international standards such as ASME B16.20, API 6A, and DIN EN 1514-2, ensuring global interoperability and reliability.
The performance of a spiral wound gasket is directly determined by the materials used for its three primary components:
| Style | Description | Typical Application | Kaxite Designation |
|---|---|---|---|
| Style R (Basic Ring) | Spiral wound body only, without inner or outer rings. For raised face (RF) flanges. | Standard raised face flanges where centering is provided by the bolts. | KX-SWG-R |
| Style CG (Inner Ring) | Spiral wound body with a solid metal inner ring. The inner ring prevents inward buckling of the winding. | Critical for tongue-and-groove, male-and-female flanges, and services with turbulent flow or high pressure. | KX-SWG-CG |
| Style CGW (Inner & Outer Ring) | Spiral wound body with both inner and outer guide rings. The outer ring provides centering and protects the winding. | The most common style for standard raised face flanges. Provides excellent handling and installation guidance. | KX-SWG-CGW |
The allowable pressure for a Kaxite spiral wound gasket depends on the flange class rating, material combination, and temperature. The following table provides a general guideline based on ASME B16.5 flanges with Flexible Graphite filler.
| Flange Class | Max. Pressure @ 38°C (100°F) | Temperature Range (Typical with Graphite) | Recommended Bolt Torque Guide |
|---|---|---|---|
| Class 150 | 275 PSI (19 bar) | -240°C to +500°C (-400°F to +932°F) | Refer to ASME PCC-1 |
| Class 300 | 720 PSI (50 bar) | -240°C to +500°C (-400°F to +932°F) | Refer to ASME PCC-1 |
| Class 600 | 1440 PSI (99 bar) | -240°C to +455°C (-400°F to +851°F) | Refer to ASME PCC-1 |
| Class 900 | 2160 PSI (149 bar) | -240°C to +425°C (-400°F to +797°F) | Refer to ASME PCC-1 |
| Class 1500 | 3600 PSI (248 bar) | -240°C to +380°C (-400°F to +716°F) | Refer to ASME PCC-1 |
| Class 2500 | 6000 PSI (414 bar) | -240°C to +350°C (-400°F to +662°F) | Refer to ASME PCC-1 |
Note: Always consult Kaxite engineering for specific application ratings, especially for non-standard materials or severe service conditions.
Q: How do I select the right metal and filler material for my application?
A: Material selection is critical. You must consider four primary factors: the chemical compatibility of the media with both metal and filler, the continuous and peak operating temperatures, the pressure range (including vacuum), and any regulatory or cleanliness requirements (e.g., FDA, NACE MR0175). For standard hydrocarbon or steam service, 304SS with Flexible Graphite is common. For strong acids like sulfuric, a nickel alloy like Alloy 20 with PTFE filler might be needed. Kaxite provides detailed chemical compatibility charts and application engineering support to ensure the optimal, safe selection.
Q: What is the purpose of the inner ring on a spiral wound gasket?
A: The inner ring, or centering ring, serves multiple vital functions. Primarily, it prevents the spiral wound body from being forced inward (radial buckling) by internal pressure or during installation, which could restrict flow or cause failure. It also provides stability during handling, acts as a compression stop to prevent over-crushing of the winding, and in services with erosion or high turbulence, it protects the vulnerable inner edge of the winding from damage.
Q: Can spiral wound gaskets be used on flat face (FF) flanges?
A: It is generally not recommended. Spiral wound gaskets are designed for use with raised face (RF) flanges or other confined flange types (like ring-type joint, tongue-and-groove). The raised face provides a defined seating area and allows the gasket to compress properly into the spiral groove. On a flat face flange, the gasket may not compress evenly, potentially leading to leakage or extrusion. For flat face flanges, a full-face gasket style is typically specified.
Q: How important is proper bolt torque and tightening sequence?
A> It is absolutely crucial. An unevenly compressed gasket will not seal effectively. Always follow a cross-pattern, multi-pass torque sequence as outlined in standards like ASME PCC-1. This ensures even flange loading and gasket compression. The final target torque value must be appropriate for the bolt size, grade, and gasket type. Under-torquing can cause immediate leakage, while over-torquing can crush the gasket's metal windings, destroying its spring action and causing future leakage during thermal cycles.
Q: Are Kaxite spiral wound gaskets reusable?
A: Spiral wound gaskets are generally considered non-reusable. Once compressed during installation, the filler material has deformed into the flange surface imperfections, and the metal windings have taken a set. Reusing a gasket will not provide the same level of sealing integrity and significantly increases the risk of leakage. For reliable performance and safety, always install a new, unused Kaxite gasket at each reassembly.
Q: How do I identify the specifications of a spiral wound gasket?
A: Kaxite gaskets are typically marked on the outer ring (if present) with essential data. This includes the size (NPS), flange class (e.g., 150#), the material codes for the winding and filler (e.g., 304/G for 304SS with Graphite), the gasket style, and often a heat number or lot code for traceability. This information is vital for verifying the gasket is correct for the service before installation.
Q: What are the key differences between Flexible Graphite and PTFE fillers?
A: The choice significantly impacts performance. Flexible Graphite offers superior thermal conductivity, excellent sealing at lower stresses, and can handle much higher temperatures (up to 500°C in inert atmospheres). It is, however, susceptible to oxidation in steam or air above 400°C and is not recommended for strong oxidizers. PTFE has near-universal chemical resistance and is excellent for aggressive chemicals at lower temperatures (max 260°C), but it exhibits greater cold flow (creep) under load, which may require retorquing. Kaxite engineers can help you weigh these properties.
