Spiral Wound Gasket with inner ring and outer ring
Spiral Wound Gaskets (SWG) are widely used as high integrity and sustainable gaskets.
It is made of metallic winding and a soft filler material, combining the strength of metal with the sealing properties of a soft filler.
This gasket is wound alternatively by V or W shaped metal hoop and non-metal filler of various kinds of materials selected based on specific working condition.
ASME B16.20 Spiral Wound Gaskets
ASME B16.20 is the most popular standard for Spiral Wound Gaskets
ASME B16.20 covers metal ring-joint gaskets, spiral-wound metal gaskets, and grooved metal gaskets with covering layers and offers comprehensive solutions
You would find the CGI SWG gasket structure as below
Inner & Outer Rings Type gasket
A inner ring and outer ring type gasket will give an additional compression limiting stopper for gasket inner and outer side. It will prevent the corrosions on flange face at annular space. – Suitable for use with flat face and raised face flanges and specified for high pressure / temperature service – Class 900 and above or where corrosive or toxic media are present.
Outer Ring(Centering Ring)
The outer ring (sometimes known as centering ring or guide ring) can be manufactured from almost any available solid metal material. The outer ring serves to centre the gasket on the flange, act as an anti blow-out device and a compression stop to prevent the filler and windings from being crushed too much.
Inner Ring
Like the outer ring, the inner ring can also be produced from most solid metal materials. The inner ring offers an additional level of protection against buckling or imploding while providing radial support to the ID of the sealing element. As it is usually the same thickness as the outer ring, it also acts as a compression stop to prevent over-tightening.
Sealing Element
The sealing element consists of a metallic winding and a soft non-metallic filler material. This part of the gaskets is where the primary sealing occurs. The sealing element can be produced from a range of different materials (listed below) to suit your individual application.
How to choose the gasket material?
To choose the right gasket material ,you should consider different factors, including temperature, pressure, chemical compatibility, and Flange type. So to understand the property and Character of the different gasket material (Ring and filler material)is very important.
You would find the character details of the gasket material as below
| Ring & Strip Materials | ||||||
| Minimum | Maximum | GuideRing Color Code | ||||
| Material | F | C | F | C | Abberviation | |
| SS 304 | -320 | -195 | 1400 | 760 | 304 | Yellow |
| SS 316L | -150 | -100 | 1400 | 760 | 316L | Green |
| SS 347L | -150 | -100 | 1400 | 760 | 317L | Maroon |
| SS 321 | -320 | -195 | 1400 | 760 | 321 | Turquoise |
| SS347 | -320 | -195 | 1700 | 925 | 347 | Blue |
| Carbon Steel | -40 | -40 | 1000 | 540 | CRS | Silver |
| Alloy 20 | -300 | -185 | 1400 | 760 | A-20 | Black |
| Hastelloy B3 | -300 | -185 | 2000 | 1090 | HASTB | Brown |
| Hastelloy C276 | -300 | -185 | 2000 | 1090 | HASTC | Belge |
| Incoloy 800 | -150 | -100 | 1600 | 870 | IN 800 | White |
| Incoloy 825 | -150 | -100 | 1600 | 870 | IN 825 | White |
| Inconel 600 | -150 | -100 | 2000 | 1090 | INC 600 | Gold |
| Inconel 625 | -150 | -100 | 2000 | 1090 | INCO 625 | Gold |
| Inconel X750 | -150 | -100 | 2000 | 1090 | INX | No Color |
| Monel 400 | -200 | -130 | 1500 | 820 | MON | Orange |
| Nickel 200 | -320 | -195 | 1400 | 760 | NI | Red |
| Titanium | -320 | -195 | 2000 | 1090 | TI | Puple |
Filler Material
The filler material is the key parts for the winding in the sprial wound gasket,it provides flexibility and ensures a tight seal.
| Material | Max Temperature (°C) | Application |
|---|---|---|
| Graphite | 550 – 850°C | High-temperature, steam, and oil & gas |
| PTFE (Teflon) | 260°C | Chemical and corrosive applications |
| Mica | 1000°C | High-temperature exhaust & combustion systems |
Standards & Specifications
Spiral wound gaskets are produced according to industry standards:
- ASME B16.20 – Standard for gaskets for pipe flanges.
- API 6A – Used in high-pressure oilfield applications.
- BS 3381 – British Standard for metallic gaskets.
- EN 1514-2 – European standard for gasket dimensions
Pressure Ratings (Class)
Spiral wound gaskets are available for various pressure classes according to ASME B16.5 and API 6A:
- ASME Classes: 150, 300, 600, 900, 1500, 2500
- API 6A Classes: 5000, 10000, 15000 psi
Typical Description of a CGI Type Spiral Wound Gasket
Product Name: CGI Spiral Wound Gasket
Size:12 Inch, DN150
Standard: ASME B16.20
Class ：150 LB
Material of Inner Ring: SS316L Stainless Steel
Material of Outer Ring: Carbon Steel
Filler: AISI 316L Hoop Filled with Flexible Graphite
Application:
It is suitable for sealing flange joints, manhole and handhold covers, tube covers, boilers, heat exchangers, press vessels, pumps, compressors and valves; industries such as petrochemical, pharmaceutical, shipbuilding, and food processing , in power industries and nuclear power station. They are ideal for steam, oil, liquids, gases, acids, alkalines, various organic mediums and solvents.
Want to learn more of the other type of Spiral Wound Gasket?
Basic type Spiral Wound Gasket (Style R Gasket)
Style RIR – (Style RIR – Flexible Graphite Filler with inner metal ring)
Style CG(Spiral wound gasket with outer ring)
