selection requires examination of three basic elements, namely:
medium being sealed
• Temperature and pressure influences
• The construction of the flange where the gasket will be fitted
the material which can be used to the best effect, must ensure that what is
being sealed will not cause gasket degradation and be able to conform to
flange irregularities without physical distortions to the flange.
Used for sealing oils, air and water at low bolt loads. Service is seen in
the heavy electrical industry in transformers and switchgear. Cork rubber has a good
resistance to oil at 80-100°C and is resistant to the effects of climate.
Many applications ranging from gearboxes, inspection covers to water piping
gaskets use rubber or CorkRubber.
With the demand for ever increasing pressures and temperatures, asbestos
jointing is now being replaced by non-asbestos composites and can be used for
high temperatures and pressures.
Used for dust or very low pressure sealing. Felts are sometimes impregnated
with oils or wax to include lubrication properties. Sponges are used for a
variety of low pressure seals/dust covers and even in cord form for ease of
installation. It is also common for sponge gaskets to be supplied with a peel
off self adhesive backing.
PAPERS AND SHIMS
Still providing good service are the engineering papers used where high
flange loads are available but low pressure is evident i.e. gear boxes. Shims
in plastic are coloured to positively identify the precise thickness to allow
for accurate settings.