SPIRAL WOUND GASKETS
Spiral wound gaskets are semi-metallic products designed for high pressure and
temperature applications and where vibration or flow rates are beyond the capability of
conventional gasket materials. They have the ability to recover under the action of
fluctuating loads caused by process fluid pressure and temperature changes, flange
rotation, bolt stress relaxation and creep.
The gasket sealing element consists of a pre-formed ‘V’ metallic winding
strip with layers of a softer, more compressible material which, during compression, is
densified and flows to fill imperfections in the flange surface when the gasket is
seated. The metalstrip holds the filler, giving the gasket mechanical resistance and
resilience.
Spiral wound gaskets can be manufactured from various filler
materials and assuming an appropriately
rated metal winding strip is selected, the operating limits of available sealing
materials are:
| Sealing Layer Material | Minimum Temperature | Maximum Temperature | Maximum Pressure | Gas Tightness | Application |
| Graphite | -200 Deg C | 450 Deg C | 400 bar | Good | Aggressive Media |
| PTFE | -200 Deg C | 260 Deg C | 100 bar | Good | Aggressive Media |
| High Temp. | -200 Deg C | 1000 Deg C | 5 bar | Average | Gases |
| High Temp. + Graphite | -200 Deg C | 800 Deg C | 100 bar | Good | Gases |
Pipeline gaskets are appropriately identified with pressure rating and size/specification
of flanges.
When correctly sized and fitted to compatible flanges, non-standard gaskets will seal
pressures up to 400 bar, although higher pressures can be considered.
Spiral wound gaskets are available in a wide range of metals/alloys; the majority, in one
of the following configurations:
Whilst standard pipeline gaskets are available with a 4.5mm thick
sealing element and 3.0mm thick inner and/or outer rings, other available sealing element
thicknesses with guide diameters and recommended
compression thicknesses are:
| Sealing Element Thickness | Minimum Diameter | Maximum Diameter | Compressed Thickness |
| 2.5mm | 10mm | 300mm | 1.9/2.1mm |
| 3.2mm | 10mm | 750mm | 2.3/2.6mm |
| 4.5mm | 10mm | 1550mm | 3.2/3.5mm |
| 7.3mm | 1500mm | 3550mm(+) | 5.1/5.6mm |
