Flexible Graphite Gaskets

I am not a gasket manufacturer, but tanged gaskets use a perforated plate as a backing with 99 to 100 pure graphite (chlorine free) pressed onto it. They can be used in place of spiral wound gaskets, but I personally would rather use a spiral wound gasket for raised face flanges as they are much more forgiving than tanged gaskets if the flanges are not properly and evenly tightened. Where tanged gaskets with graphite are very useful is for high temperature applications that require complex shapes where a spiral wound would be of no use.

I do not think there is much difference in the cost, though the making of spiral wound gaskets is more labour intensive as the inner and outer rings, if fitted, are often still inserted by hand

Hi,

Interesting question, and very accurate answer by The Prof.

This is an elaboration.

There is an infinite variety of graphite-SS gaskets of this "tanged" and other varieties.

Mazda Manufacturers makes both, tanged graphite-SS and spiralwound gaskets. Yes, for Round Raised flanges, spiral wound gasket is often the best option because it can tolerate misalignments.

For long, inadequately supported (or inadequately temperature-compensated), horizontal pipelines, a specific variety of Spiralwounds, Mazda CB-DJ, can actually help the system provide the reaction forces to counter the hogging or sagging bending moments in the long pipelines.

Tanged graphite-SS gaskets are much superior in other ways. However, the construction is important: the specific variety, in which SS tang is pierced so as to create work hardened spikes, is the best. During manufacture, the graphite sheets are calendered (pressed) onto the tanged sheet. The tangs penetrate the graphite, and bend over behind the graphite so as to hold the graphite mechanically. This sheet is superior to all other varieties, in which graphite is merely stuck onto SS sheet, and the temperature endurance is determined by the adhesive, not by the graphite.

It is essential to buy the ready gasket from the manufacturer, since specialised tooling is required to cut the gasket. Attempts to cut the sheet at user's end have not succeeded so far, due to the swarf (burr) on the SS sheet which interferes with sealing.

For complex systems, custom-made combinations of spiral wound gasket and tanged graphite are manufactured. This is useful where in a system, the two flat flanges carry a plurality of channels carrying fluids at different pressures and temperature. This system is especially popular for cylinder head gaskets.

N. M. Havewala. havewala@gmail.com skype: NMHavewala.

Mazda Manufactures. mazda@vsnl.com .

Thanks Prof/ Havewala,

These posts were indeed helpful. Just wanted to know the cost comparison between these two kinds of gaskets.

Also, could you give me the catalogue of tanged insert gasket if you have it. I looked in google but couldnt find a proper catalogue.

thanks!