The concept of spiral wound gasket construction was originated by
Flexitallic in 1912, inaugurating the beginning of a new era in
safe, effective sealing. The primary purpose for this development
was the increasingly severe temperatures and pressures used by U.S.
refinery operators in the first half of the century.
The necessity for a gasket to have the ability to recover cannot be
over emphasized. The effects of pressure and temperature
fluctuations, the temperature differential across the flange face,
together with bolt stress relaxation and creep, demand a gasket
with adequate flexibility and recovery to maintain a seal even
under these varying service conditions. The Spiral Wound Gasket is
the precision engineered solution to such problems, meeting the
most exacting conditions of both temperature and pressure in
flanged joints and similar assemblies and against virtually every
known corrosive and toxic media.The spiral wound gasket meets the
most exacting conditions of both temperature and pressure in
flanged joints and similar assemblies and against every known
corrosive and toxic media.
ASME B16.20 which covers spiral wound gaskets requires the use of
solid metal inner rings in: Pressure Class 900, nominal pipe sizes
24 and larger, Pressure Class 1500 from nominal pipe sizes 12 and
larger, Pressure Class 2500 from nominal pipe sizes 4 and larger
and all PTFE filled gaskets. In the same standard is also described
how a spiral wound gasket should be characterized, below you will
find a image on it.
Basic Type
Basic construction type, inner and outer diameters are reinforced
with several piles of metal without filler to give greater
stability and better compression characteristics. - Suitable for
tongue and groove, male and female or grooved to flat face flange
assemblies.
Inner Ring Type
Solid inner metal ring acts as a compression stopper. To prevent
accumulation of solids, reduce turbulent flow of process fluids and
minimize erosion, damages of gasket between flange bore and the
inside diameter, the annular space is filled up by solid inner
metal ring. - Suitable for male and female pipe flanges.
Outer Ring Type
Solid outer ring accurately locates the gasket on the flange face
to give the additional radial strength to prevent the gasket
blowout and acts as a compression limiter. In case of installing
the outer ring, it is very easy to install the gasket to flange
face because the end of outer ring will touch at bolts - Suitable
for use with flat face and raised face flanges. For class 900 and
above an internal ring is recommended.
Inner & Outer Rings Type
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.
Product Description
tructural material of metallic wrapping pad:
Filling | Steel band | Inner ring | Outer ring |
| Asbestos wrapping | SUS 304 | Carbon steel | Carbon steel |
| Graphite wrapping | SUS 316 | SUS 304 | SUS 304 |
| Teflon wrapping | SUS 316L | SUS 316 | SUS 316 |
| | SUS 316L | SUS 316L |
| Filling | Temperature(ºC) | Max operating pressure(kg/cm2) |
| Asbestos wrapping | -200~550 | 250 |
| Graphite wrapping | -150~450 | 100 |
| Teflon wrapping | 240~260 | 100 |
Product name | AISI | Hardness(HB/HV) | Temperature(°C) |
| 304 Stainless steel | 304 | 130~180 | -250~+550 |
| 316 Stainless steel | 316 | 130~180 | -100~+550 |
| 316L Stainless steel | 316L | 130~190 | -100~+550 |
Flange type and form of wrapping pad:
Flange type | Spiral wound gasket form |
| Flat face flange(F.F) | Wrapping pad with outer ring only |
| Wrapping pad with inner and outer rings |
| Raised face flange(R.F) | Wrapping pad with outer ring only |
| Wrapping pad with inner and outer rings |
| Male and female flange(M & F) | Basic wrapping pad |
| Wrapping pad with inner ring only |
| Tongue and groove flange(T & F) | Basic wrapping pad |
| Wrapping pad with inner ring only |
| Flat and groove flange(F & G) | Basic wrapping pad |
| Wrapping pad with inner ring only |
Item | Thickness(mm) | Tolerances(mm) |
| Gasket thickness | 4.5, 3.2 | +0.2
-0.1 |
| Ring thickness | 3.0 | ±0.24 |
