Executive Summary

Spiral wound gaskets are a proven, versatile sealing solution for high-pressure and high-temperature flanged joints. This page explains construction variants, selection criteria (filler, centring ring, windings, metal type), installation best practices, common failure modes and downloadable datasheets to support procurement, engineering design and maintenance teams.

What is a Spiral Wound Gasket?

A spiral wound gasket consists of a continuous strip of metallic material wound in an open spiral with a softer filler (graphite, PTFE, mica) inserted between the windings. Optional inner and outer centring rings (metal or soft) provide flange protection, prevent overcompression and help installation alignment. The wound geometry provides springiness, allowing the gasket to recover after thermal cycles and maintain contact stress.

Classification — By Metal, Filler, and Configuration

By Metal (Winding)

  • Stainless steel (304 / 316) — common, corrosion resistant
  • Inconel / Alloy (600/625) — for high temperature or corrosive services
  • Soft iron or carbon steel — used when cost and compatibility permit

By Filler

  • Flexible graphite — high temperature, good compressibility
  • PTFE — excellent chemical resistance, low friction
  • Mica or ceramic fillers — high temperature electrical insulation or specific chemical needs

By Configuration

  • Standard spiral wound (no rings)
  • With inner metal centring ring (protects bore & avoids inward extrusion)
  • With inner and outer rings (full support & flange protection)
  • ASME/EN standard sizes, RTJ-adapted versions and custom OD/ID/thickness

Selection Guide — How to Choose the Right Spiral Wound Gasket

  1. Identify service conditions — temperature ranges (steady and spikes), pressure class, and whether service is oxidizing.
  2. Choose filler — graphite for high-temp steam, PTFE for aggressive chemicals; verify chemical compatibility at concentration and temperature.
  3. Select winding metal — stainless for general service; Inconel or higher alloy for hot corrosive environments.
  4. Decide on centring rings — inner rings prevent inward extrusion on ring gaskets; outer rings protect flange faces and help with bolt loading.
  5. Thickness & turns — thicker gaskets and more turns improve sealing on coarse flanges but require higher bolt load; consult ASME/EN guidelines.
  6. Surface finish & flange class — check flange finish and rating; choose gasket class and preload accordingly.

Tip: For thermal cycling and vibration use gaskets with adequate winding turns and consider stainless steel winding with graphite filler plus inner centring ring for reliability.

Technical Parameters & Common Specifications

Typical reference values
Configuration Filler Typical Temp Range (°C) Pressure Class Common Thickness (mm)
SS winding / Graphite filler Flexible graphite -200 to 450 ASME Class 150 — 2500 3 / 4.5 / 6 / 9
SS winding / PTFE filler PTFE -200 to 250 Up to Class 600 (check design) 3 / 4.5 / 6
Inconel winding / Graphite filler Graphite -200 to 650 High pressure & temp services 3 / 4.5 / 6
Graphite winding / Mica filler Mica/ceramic Up to 800 (special) High temp applications Varies

Common Standards & Size Ranges

Standard Typical Range Notes
ASME B16.20 / API Class 150 — 2500, OD/ID to fit flanges Most common industrial spiral wound specs
EN / DIN PN6 — PN640 equivalents European flange compatibility
Custom Special OD / ID / thickness Die-cut or built-to-order for unusual flanges

Product Data & Technical Documents

Download spiral wound datasheets, ASME sizing tables, filler chemical charts and installation templates.

Installation, Bolt Tightening & Maintenance

  1. Face preparation: remove old gasket, clean flange faces and inspect for damage or warpage.
  2. Use correct centring: fit inner centring ring where specified to prevent extrusion and protect bore.
  3. Tightening sequence: torque bolts in a star pattern in multiple increments to specified torque values; spiral wound gaskets need correct bolt preload to seat filler.
  4. Run-in & re-torque: some services require re-torque after initial thermal cycle — follow datasheet guidance.
  5. Inspection: periodic inspection recommended for critical services; look for extrusion, blowout signs or loss of seating stress.
  6. Replacement: replace gaskets after severe thermal shock, flange repairs or when damage observed — do not reuse compressed spiral wound gaskets.
spiral wound gaskets
Basic installation flow: clean → centre → torque in steps → inspect after initial run.

Application Industries & Case Studies

  • Refining & petrochemical — high pressure process lines
  • Power generation — steam lines, heat exchangers
  • Oil & gas pipelines — high pressure trunk lines and risers
  • Chemical plants — aggressive media with temperature cycling
  • Marine & offshore — robust sealing in harsh environments

Case Study — Steam Heat Exchanger Leak Repair

Problem: Repeated leaks on 600# steam exchanger flanges due to thermal cycling. Solution: Upgraded to Inconel-wound spiral with graphite filler and inner centring rings; increased specified bolt preload and improved flange face finish. Result: Leakage eliminated and maintenance intervals extended significantly.

Performance Comparison & Material Matrix

Property SS/Graphite Inconel/Graphite SS/PTFE Compressed Sheet
Temperature range -200 → +450°C -200 → +650°C -200 → +250°C -40 → +230°C
Pressure capability High Very High High Moderate
Chemical resistance Good Good (alloy) Excellent (PTFE) Varies
Thermal cycling Excellent Excellent Good Fair
Suitability for coarse flange Good (with rings) Good Better with outer ring Depends

Common Failures & Troubleshooting

Leakage under pressure
Cause: Insufficient bolt preload, wrong gasket thickness, missing centring ring. Action: Re-torque per sequence, verify gasket configuration and retest with correct preload.
Filler extrusion / blowout
Cause: No inner ring on ring gaskets or too low winding metal strength. Action: Use inner centring ring and select higher density winding/metal; consider outer ring for flange protection.
Loss of seal after thermal cycling
Cause: Wrong filler or insufficient spring effect (too few turns). Action: Select appropriate filler (graphite for high temp) and increase turns/thickness as required.
Corrosion of winding
Cause: Incompatible metal selection for media. Action: switch to corrosion-resistant alloy (316, Inconel) and verify with chemical resistance data.

FAQ — For Purchasing / Engineering / Maintenance

Q: When is an inner centring ring required?A: Inner centring rings are recommended for ring gaskets to protect the filler from inward extrusion and to prevent gasket displacement into the pipeline bore. They are essential for low-confinement or high-pressure ring applications.
Q: How many turns / windings are typical?A: Typical designs specify multiple filler/metal windings; product datasheets indicate turns per mm or nominal cross-section. More turns generally improve sealing and recovery but require correct preload.
Q: What info speeds up a quote?A: Provide flange standard (ASME/EN), pressure class, OD/ID/thickness or flange drawing, filler preference (graphite/PTFE), winding metal and whether centring rings are required.

Need help specifying spiral wound gaskets?

Contact our technical team for selection assistance, material certificates and custom build options.
Spiral Wound Gasket Technical Data Sheet (PDF) Request quote Contact technical team
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