SPIRAL WOUND
GASKETS
Spiral wound gaskets consist of a metal strip with a “V” profile wound in a spiral form and filled with soft material.
The soft material provides the spiral wound gasket with sealing properties and the metal strip provides the stiffness properties.
The combination of these two types of materials makes spiral wound gaskets ideal for sealing fluids at high temperatures (up to 1000°C) and under high pressure conditions (up to 250°C).
“Mechanical durability, high flexibility and exceptional recovery in heavy operation conditions”
- With inner ring, outer centering ring or both.
TA LUFT Fugitive Emissions Prevention Certificate (environmentally friendly)- Standard sizes acc/to ASME, EN or to customers specifications.
- SS304L, SS316L, SS321.
- Successfully used in a wide range of applications: piping, heat exchangers or pressure vessels on steam, petrochemical, nuclear and marine plants.
- Extraordinary ability to adapt with recovery and flexibility under frequent fluctuations of pressure and temperatures.
Materials
In general, the metal strip of the spirals is manufactured in the classic 18/8 type stainless steels (AISI-316L, AISI-304, AISI-321), special stainless steels (AISI-309 or similar) and other materials such as Monel-400, Titanium, etcetera.
The soft filling (material that specifically performs the sealing function) can be supplied in Graphite, PTFE, ceramic material or other asbestos-free materials.
Profiles
The most common nominal thicknesses for spirals are 3.2 mm and 4.5 mm.
For diameters up to 1200 mm, 4.5 mm thickness is recommended; for diameters up to 1800 mm, 5.5 mm thickness and for sizes up to 4000 mm, 6.5 mm or 7 mm thickness is recommended.
for sizes up to 4000 mm it is advisable to use 6.5 mm or 7 mm thickness.
Profiles and values
| Profile | Section | Material/ Coating | KO | K1 | RZ * |
| [N/mm] | [mm] | (µm) | |||
| SpV1 |  |
Steel |
50 bD | 1,3 bD |
12,5 a 25 |
| SpV2 |  |
55 bD | 1,4 bD | ||
| SpV2J |  |
55 bD | 1,4 bD | ||
| SpZ1J |  |
CrNi steel |
40 bD |
1,2 bD |
25 a 50 |
| SpZ2J |  |
*Recommended surface finish for the surface of the flange
We also manufacture spiral wound gaskets for fittings and equipment. It is also possible to manufacture oval shapes (for manholes) and there is also the possibility to manufacture special spiral wound gaskets with metal-plastic ribs for heat exchangers.
Spiral wound seals with an inner retaining ring are also available (profiles SpV1J, SpV2J). The inner ring makes the seal safer by protecting the spiral from the possible turbulent action of the fluid and from pressure and/or temperature oscillations, additionally preventing the lateral sliding effect that could occur.
In SpZ (zone) profile spiral wound seals, the filling is usually made of graphite and the middle zone of PTFE or special compressible graphite. In this type of seals, lower closing deformation forces are required, as the surface pressure is mainly concentrated in the middle zone.
The minimum surface pressure is 30 N/mm2, instead of the 45-50 N/mm2 that would be required for a normal gasket. The combined filler (the zone) also protects the gasket better against high pressures or varying load conditions, and its configuration allows it to withstand higher stresses than a normal gasket.
With spiral wound seals, values of 10-8 mbar/ s-1 m-1 (measured with a Helium leak detector) can be achieved, considering a central PTFE zone of DN-150.
Spiral wound gaskets profile SpFS in “fire-safe” version are equipped with PTFE-filled tapes on the inside and graphite-filled tapes on the outside. They are suitable for applications where the product must not come into contact with graphite and where the operating temperature is below 280°C.
For temperatures above 280°C with the requirement of “fire-safe“, SpV spiral wound gaskets with graphite tape on the outside or SpZ gaskets with graphite zone can be used.
Surface pressure
|
Profile |
Material |
Surface pressure (N/mm2) | |||
| T = 20ºC | T = 300ºC | ||||
| smin | smáx | smin | smáx | ||
| SpV1 SpV2 |
1.4541/Graphite | 50 | 150 | 60 | 120 |
|
SpV1J, SpV2J SpZ1, SpZ2 |
1.4541/Graphite 1.4541/Graphite: PTFE |
50 30 |
300 150 |
60 45 |
220 120 |
| SpZ1J, SpZ2J | 1.4541/Graphite: PTFE | 30 | 300 | 45 | 220 |
|
SpV1 *, SpV1J * SpZ1 *, SpZ1J * |
1.4541/Graphite 1.4541/Graphite+ PTFE |
70 70 |
View note View note |
70 70 |
View note View note |
Note: Spiral wound metals marked with (*) are assumed to be confined in a tongue and groove pocket; the seal is based on metal-to-metal contact, which is why the upper limit of the smáx is not limited by the gasket material but by the strength of the flange.