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DN200 SS316L CL150 B16.20 RF 4.5mm Graphite Filler Gasket Spiral
Wound
What is Spiral Wound Gasket?
Why did we call it SWG? SWG is a short form of Spiral Wound Gasket.
These gaskets are fabricated from thin metal strip sandwiched
between layers of non-metallic filler. SWG has
alternative spiral layers of thin metal sheet and filler material
as shown in the image. Here in the cross-section,
the blue layers are of metal, and the black layers are of filler
material. As these layers are wounded in continuous spiral forms,
these types of gaskets are known as spiral wound gasket.
Thickness
The standard manufacturing thickness for spiral wound gaskets are:
3.2 mm; 4.5 mm; 6.5 mm
(measured across metallic strip not including the filler, which
protrudes slightly beyond the metal).
Manufacturing tolerances
The tolerance of the gasket diameters (d1, d2, d3, d4, s, s1) are
stipulated by ASME B 16.20 and
DIN 2632-2638 standards. The gaskets designed for non-standard
flanges meet the recommendations by the ASME B 16.20.
Dimensions
The dimensions of the standard SWG meet the ASME, BS and EN (DIN)
standards.
| NPS) | Classes 150, 300 | Class 150 | Class 300 | Class 150 | Class 300 |
|---|---|---|---|---|---|
| Inch | mm | Inside Diameter | Outside Diameter | ||
| 1⁄2 | 31.8 | 19.1 | 19.1 | 47.8 | 54.1 |
| 3⁄4 | 39.6 | 25.4 | 25.4 | 57.2 | 66.8 |
| 1 | 47.8 | 31.8 | 31.8 | 66.8 | 73.2 |
| 1 1⁄4 | 60.5 | 47.8 | 47.8 | 76.2 | 82.6 |
| 1 1⁄2 | 69.9 | 54.1 | 54.1 | 85.9 | 95.3 |
| 2 | 85.9 | 69.9 | 69.9 | 104.9 | 111.3 |
| 2 1⁄2 | 98.6 | 82.6 | 82.6 | 124 | 130.3 |
| 3 | 120.7 | 101.6 | 101.6 | 136.7 | 149.4 |
| 4 | 149.4 | 127 | 127 | 174.8 | 181.1 |
| 5 | 177.8 | 155.7 | 155.7 | 196.9 | 215.9 |
| 6 | 209.6 | 182.6 | 182.6 | 222.3 | 251 |
| 8 | 263.7 | 233.4 | 233.4 | 279.4 | 308.1 |
| 10 | 317.5 | 287.3 | 287.3 | 339.9 | 362 |
| 12 | 374.7 | 339.9 | 339.9 | 409.7 | 422.4 |
| 14 | 406.4 | 371.6 | 371.6 | 450.9 | 485.9 |
| 16 | 463.6 | 422.4 | 422.4 | 514.4 | 539.8 |
| 18 | 527.1 | 474.7 | 474.7 | 549.4 | 596.9 |
| 20 | 577.9 | 525.5 | 525.5 | 606.6 | 654.1 |
| 24 | 685.8 | 628.7 | 628.7 | 717.6 | 774.7 |
Strength of Spiral Wound Gasket
Spiral Wound Gasket is the ideal gasket in the semi-metallic
category. A narrow strip of V-shape metal hoop is spirally wound
under tension with a filler cushion between the lamination of the
metal and is spot-welded at both ends.
This unique construction of a spring-like metal and soft filler
provides gasket excel-lent characteristics.
Resistance to high temperature and high pressures.
Excellent sealability is maintained with comparatively small gasket
area.
Great resilience which allows the gasket to adjust automatically to
change in operating conditions, such as pressure and
These gaskets are extremely popular due to the wide variety of
available styles and sizes.
SWG can be fabricated of any metal which is available in thin strip
and which can be welded; therefore, they can be used
against virtually any corrosive medium.
They can be used over the complete temperature range from cryogenic
to approximately 1093ºC. This type of gasket can
be used in all pressures from vacuum to the standard 2500 pressure
class flange ratings.
Relatively low-density Spiral wound gaskets are used in vacuum
service whereas extremely high-density Spiral wound gaskets
are used in high-pressure service. The density of gasket is nothing
but a number of layers of filler and metal strip in the given
width of the gasket.
Tolerance in the Dimension of the Spiral Gasket
Thickness tolerance is ±0.13 mm measured across the metallic portion of the gasket, not including the filler, which may protrude slightly beyond the metal.
Outside diameter tolerance for NPS 1⁄2 through NPS 8 is ±0.8 mm; for NPS 10 through NPS 24, +1.5 mm, −0.8 mm.
Inside diameter tolerance for NPS 1⁄2 through NPS 8 is ±0.4 mm; for NPS 10 through NPS 24, ±0.8 mm.
The centering ring outside diameter tolerance is ±0.8 mm.
