Grooved gaskets0 pages

Grooved gaskets

Types of gaskets
Grooved gaskets have proven extremely useful in all areas
of industry, including the most demanding sealing tasks.
Our grooved gaskets can be found in conventional power
plants as well as in the primary circuit of nuclear power plants.
In nuclear power plants, they are used e.g. as a heat exchanger gasket, as a valve cap gasket or as a manhole
cover gasket on steam generators or pressurisers.
Grooved gaskets have also been used to great success in
the chemical and petrochemical industries. Particularly in
places where there are high pressures and temperatures,
and therefore high bolt loads, to contend with. In order to
avoid damage to the flanges by the metal core, grooved gaskets are generally used with layers of PTFE, graphite, aluminium or silver. This gives total protection to the flanges, as
the profile geometry has been specifically adjusted to suit
the thickness of the layer.
We have developed a range of profiles to suit the various
properties of the layer materials.
The principal purpose of the soft layers is not however to
protect the flanges, but to provide a secure seal even at low
minimum surface pressures. A triaxial stress is created in
the profiling of the metallic carrier which has been filled with
the layer material. The load capacity is limited by the breaking point of the gasket and/or flange material. The stability of
this combination is therefore significantly higher than with a
pure PTFE, graphite, aluminium or silver seal.
Grooved gaskets be produced in sizes ranging from a few
millimetres to a diameter of 4,500 mm on our lathes. The
possibility of producing gaskets with greater diameters or
one-off production from drawings, such as oval gaskets,
can be examined in individual cases. For gaskets in heat
exchangers with partitions, it is necessary to insert partitions
with grooves of the same profile.

Gaskets for flanges with raised face or for smooth flanges
are supplied with a centring ring, so that the gasket is centred on the bolts. If the width of the centring ring is <= 10 mm,
then this ring is a part of the gasket (fixed central frame). At
greater widths, the integrated has a stress-relieving groove
(illustration 1). A loose centring ring should be used with
gaseous media. The loose centring ring is also advantageous where there are large differences in temperatures
between internal and external diameters. The loose centring ring is fitted in a groove (illustration 2 and 3).

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The illustrations show the layout for a nominal thickness of
the metal core of 4 mm.

Illustration 1
Illustration 2

Illustration 3

Grooved gaskets are available that conform to works standards WN 100, WN 101, WN 136, WN145 (DINEN 1514-6),
WN 146 and WN 147. Works standards 100 and 101 only
contain a sealing width for all nominal pressure levels.
The sealing width bG = (d2 - d1)/2 should always increase as
the nominal pressure level increases. Due to the extremely
large difference between σϑ and σV, in grooved gaskets, as
expressed in the application security SB = √ σϑ/σV , works
standards 100 and 101 can be simplified.

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Kempchen Dichtungstechnik GmbH · Tel. +49 (0)208 8482 0 · Fax. +49 (0)208 8482 285 · info@kempchen.de · www.kempchen.de

Grooved gaskets

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