Stockist & supplier ASME B16.20 · ASME B16.5 · ASME B16.47 · EN 1514-2
Spiral Wound Gaskets — ASME B16.20
Spiral wound gaskets are semi-metallic gaskets made of a V-shaped metal strip wound with a soft filler, used on raised face flanges. Teshi Group stocks and supplies spiral wound gaskets to ASME B16.20 for ASME B16.5 and B16.47 flanges in Class 150 to 2500.
Also called: SWG, spiral gasket, CG gasket, CGI gasket, SPW gasket
What is a Spiral Wound Gasket?
A spiral wound gasket alternates a preformed metal winding strip with a filler such as flexible graphite or PTFE, spot-welded at start and finish. The metal gives resilience and blow-out resistance; the filler seals the flange surface. An outer (centring) ring locates the gasket inside the bolts and limits compression; an inner ring protects the winding from turbulence and prevents buckling. Spiral wound gaskets are the standard choice for raised face flanges in refinery, petrochemical and steam service across a wide temperature and pressure range.
Key features
- Winding: SS 304, 316L, 321, 347; Alloy 625, 825, C276, Monel 400, titanium
- Filler: flexible graphite, PTFE, mica / vermiculite
- Outer ring (CG), inner and outer ring (CGI) and winding-only (R) styles
- Colour-coded outer rings and filler stripes per ASME B16.20
- Sizes for ASME B16.5 NPS ½–24 and B16.47 Series A/B NPS 26–60
Specification
| Supply | Stockist & supplier — Teshi Group, India |
|---|---|
| Standard | ASME B16.20 Part SW; EN 1514-2 for PN flanges |
| Flange standards | ASME B16.5 (NPS ½–24), ASME B16.47 Series A and B (NPS 26–60) |
| Pressure class | Class 150, 300, 400, 600, 900, 1500, 2500 |
| Winding materials | 304, 304L, 316, 316L, 321, 347, 310, 904L, 254 SMO, duplex 2205, super duplex 2507, Monel 400, Inconel 600, Inconel 625, Incoloy 800, Incoloy 825, Hastelloy C276, Hastelloy C22, Hastelloy B2, Alloy 20, Nickel 200, titanium Gr 2 |
| Filler | Flexible graphite, PTFE, mica / vermiculite |
| Outer ring | Carbon steel (painted or zinc plated), stainless steel |
| Inner ring | Required for PTFE filler; for all fillers at NPS 24+ Class 900, NPS 12+ Class 1500, NPS 4+ Class 2500; supplied with graphite filler unless purchaser specifies otherwise |
| Documents | Manufacturer's test certificate / EN 10204 3.1 for metal parts, dimensional inspection report |
Applications
- Refinery and petrochemical flanges
- Steam and boiler piping
- Heat exchanger and pressure vessel joints
- Hydrocarbon and chemical process lines
- Cyclic temperature and pressure service
Spiral wound vs ring joint gasket
Spiral wound gaskets seal on raised face flanges and tolerate moderate surface imperfections, flange rotation and thermal cycling. Ring joint gaskets are solid metal rings that seat in machined grooves of RTJ flanges and are used for very high pressure and temperature, mostly Class 900 and above and wellhead equipment. RTJ needs matching ring-groove flanges; spiral wound gaskets cannot be used in RTJ grooves.
Technical data sheets
FAQ
Spiral Wound Gasket: common questions
When is an inner ring required on a spiral wound gasket?
ASME B16.20 requires inner rings with PTFE filler, and for all fillers at NPS 24 and larger in Class 900, NPS 12 and larger in Class 1500 and NPS 4 and larger in Class 2500. Graphite-filled gaskets are supplied with inner rings unless the purchaser specifies otherwise.
What do the gasket colours mean?
ASME B16.20 colour codes identify the winding metal (outer ring colour) and the filler (stripe on the ring edge), so material can be checked at site without testing.
Which filler should I choose?
Flexible graphite suits most hydrocarbon and steam service. PTFE suits strong chemicals at lower temperatures. Mica or vermiculite filler is used for high-temperature oxidising service.
Can spiral wound gaskets be reused?
No. Once compressed, the metal winding and filler deform permanently and will not recover their original thickness. Fit a new spiral wound gasket every time the flange joint is opened.
Need a size or grade not listed here?
We source against your specification from approved mills, with mill test certificates and inspection before dispatch.
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From mill heat to your site
- 01
Approved mill material
Received against the mill certificate; heat number registered.
- 02
Forging & machining
Heat number carried through every stage in our Indian works.
- 03
PMI, dimensional & NDT
Every lot inspected to the governing standard; TPI witness on request.
- 04
Stamped & certified dispatch
Hard-stamped pieces with EN 10204 3.1 / 3.2 certificates.
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