Steel Pipe Flange Gasket Types: Spiral Wound, Ring Joint, Sheet
Selecting the correct flange gasket is critical for achieving leak-free sealing in piping systems. This comprehensive guide covers the main gasket types used with steel pipe flanges: spiral wound, ring joint (RTJ), compressed fiber sheet, and kammprofile gaskets.
Understanding Flange Gaskets
A flange gasket creates a seal between two flanged pipe connections. The gasket must:
- Withstand system pressure and temperature
- Resist the fluid or gas being contained
- Maintain seal under bolt load
- Accommodate flange surface irregularities
1. Spiral Wound Gaskets
Construction
Spiral wound gaskets consist of alternating layers of:
- Metal Strip: V-shaped or W-shaped winding (typically 304SS, 316SS, or alloy)
- Filler Material: Flexible graphite, PTFE, or ceramic
- Outer Ring: Carbon steel guide ring (for centering)
- Inner Ring: Optional metallic inner ring (prevents inward buckling)
Specifications
| Parameter | Specification |
|---|---|
| Style | ASME B16.20 (standard), Custom |
| Pressure Class | Class 150 to 2500 |
| Temperature Range | -196°C to 1000°C (depending on filler) |
| Common Sizes | 1/2″ to 60″ |
| Winding Material | 304, 316, 321, 347, Inconel |
| Filler | Graphite (-200 to 650°C), PTFE (-196 to 260°C) |
Advantages
- Excellent for high-temperature and high-pressure applications
- Withstands thermal cycling without losing resilience
- Metal winding provides structural integrity
- Suitable for flanges with poor surface finish
- Reusable in many cases
Disadvantages
- Higher cost than sheet gaskets
- Requires proper installation technique
- Not suitable for very low pressure applications
Applications
- Oil and gas refineries
- Petrochemical plants
- Power generation
- Steam systems
- Chemical processing
2. Ring Joint (RTJ) Gaskets
Construction
Ring Joint gaskets are metallic seals designed for use with RTJ flanges (ASME B16.5). They feature:
- Metal Body: Octagonal or oval cross-section
- Material: Soft iron, carbon steel, 304/316 stainless, alloy steels
- Sealing Mechanism: Deforms into flange grooves under bolt load
Types
- Octagonal: Standard, higher gasket stress, better seal
- Oval: Legacy design, easier to install
- BX: Pressure-balanced design for high-pressure wellhead equipment
- RX: Reusable, pressure-energized design
Specifications
| Parameter | Specification |
|---|---|
| Standard | ASME B16.20, API 6A |
| Pressure Class | Class 2000 to 15000 (API 6A) |
| Temperature Range | -29°C to 800°C |
| Ring Sizes | R11 to R105 (ASME B16.20) |
Advantages
- Metal-to-metal seal provides extreme reliability
- Ideal for high-pressure and high-temperature service
- Withstands significant flange rotation
- Excellent for cyclic temperature/pressure conditions
- No flange damage from over-compression
Disadvantages
- Requires special RTJ flanges (cannot use with RF flanges)
- Metal seal can be damaged if improperly installed
- Higher cost than sheet gaskets
Applications
- Oil and gas wellhead equipment
- Subsea pipelines
- High-pressure valves
- Drilling rigs
- High-pressure chemical processing
3. Compressed Fiber Sheet Gaskets
Construction
Compressed fiber sheet gaskets are made from:
- Fiber Base: Aramid, mineral, or glass fibers
- Binder: NBR (nitrile), SBR, or EPDM rubber
- Filler: Various inorganic fillers
Types
- Aramid (Kevlar): General purpose, good strength
- Mineral: Cost-effective, good for water and steam
- Glass-Fiber: High-temperature capability
- Carbon-Fiber: High-temperature and pressure
Specifications
| Parameter | Specification |
|---|---|
| Standard | ASME B16.21, DIN 2690 |
| Pressure Class | Up to Class 300 (limited by material) |
| Temperature Range | -30°C to 400°C (depending on grade) |
| Thickness | 1.5mm, 3.0mm standard |
Advantages
- Low cost
- Easy to cut and install
- Wide range of compatible fluids
- Suitable for low-pressure applications
- Good for raised face and flat face flanges
Disadvantages
- Not suitable for high-pressure applications
- Poor resistance to thermal cycling
- Cannot be reused
- Limited temperature range
Applications
- HVAC systems
- Water and drainage piping
- Low-pressure steam
- General industrial applications
4. Kammprofile Gaskets
Construction
Kammprofile gaskets (also called camprofile) feature:
- Metal Core: Corrugated steel strip with concentric grooves
- Sealing Layer: Soft facing material (graphite, PTFE, or mica)
- Outer Ring: Carbon steel guide ring (optional)
Specifications
| Parameter | Specification |
|---|---|
| Standard | ASME B16.21 (dimensions) |
| Pressure Class | Class 150 to 2500 |
| Temperature Range | -196°C to 650°C (graphite) |
| Face Width | Narrow to standard |
Advantages
- Excellent sealability with low bolt load
- Stable under thermal cycling
- Reusable
- Self-centering design
- Suitable for narrow flange faces
Disadvantages
- Higher cost than sheet gaskets
- Cannot be used with damaged flanges
- Careful handling required
Applications
- Heat exchangers
- Turbines
- Compressors
- High-temperature service
Gasket Selection Guide
| Application | Recommended Gasket |
|---|---|
| High Pressure/Temperature | Spiral Wound or RTJ |
| Oil & Gas Wellhead | Ring Joint (RTJ) |
| Steam Service | Spiral Wound (Graphite) |
| Chemical Processing | Spiral Wound or Kammprofile |
| Water Service | Fiber Sheet |
| HVAC | Fiber Sheet |
| Low Bolting Load | Kammprofile |
Conclusion
Selecting the right flange gasket type depends on your specific application requirements. Spiral wound gaskets offer the best versatility for most industrial applications, while RTJ gaskets are essential for high-pressure oil and gas service. Fiber sheet gaskets provide cost-effective sealing for lower-pressure applications.
Need help selecting the right gasket for your application? Contact Xi’an Coremetal Steel for technical support and product availability.
Contact: Tracy | Email: tracy@coremetalsteel.com | Phone: +86 18291910632