Flat gaskets0 pages

Flat gaskets made from graphite, fibre, PTFE, elastomer

Soft-material gaskets are universal sealing elements with a
large range of application in all branches of industry. They
can be used within a temperature range of - 200 °C up to a
maximum of + 550 °C. A suitable material should be selected depending on the medium, medium concentration,
temperature and type of flange being used.
We produce flat gaskets in all commonly-used soft materials. See also the section “Materials commonly used”. As a
general rule, thin gaskets are preferred to thicker ones.

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Flat gaskets made from soft material are available in ring
shape, as frames, as oval gaskets and practically any other
special kind of shape. To close the porous interfaces in fibre
sheet gaskets (FA) or in expanded flexible graphite or
RivaTherm Super, gaskets are rimmed on the inside with a
thin metal band.
Gaskets with outer rim made of a thin metal band are used
where the media wear comes from the outside. This is the
case, for example, with self-sealing manholes, head access hole locks or even in construction apparatus, if internal
fixtures need to be sealed. So as to avoid misunderstandings,
it must be noted that this gasket profile is not a gasket with a
reinforced outer ring, as mentioned in the applicable regulations under "blowout proof gasket with metal outer ring".

The usual thickness of gaskets is 1; 1.5; 2 and 3 mm. PTFE
gaskets should be used in the thinnest size possible due to
cold flow.
The surface finish and evenness of the flange should determine the gasket thickness to be used. The better the flange
surface, the thinner the gasket can be. Soft-material gaskets
require only low seating surface pressure σV, but can be
more easily overloaded than metal gaskets or metal/softmaterial gaskets, especially at narrower gasket widths.
In order to avoid collapse, the sealing surface pressure must
be between σV and σϑ and the following width/height relationships must be complied with:

Bordering with a thin inner and outer metal band can be
useful in preventing the extrusion of the soft sealing material
into gaps, as can happen for example when used in flange
connections with male and female faces.
It must be taken into account, that the characteristic of gaskets for tongue and groove-according to DIN, EN resp. ANSI
standard-with inner and/or outer rim corresponds with a
metal jacketed gasket.

Width / height relationships:
Material

Profile A1 Flat gasket made of soft material with a rectangular cross-section

bG/hG >

Graphite with reinforcement

8

Graphite without reinforcement
Fibre sheet

10

PTFE

Profile F1 internal with a thin metal band rim

12
20

Profile F7 with an internal and external rim of thin metal

If smaller relationships arise due to design considerations,
the gaskets must be encased, e.g. using tongue and groove
or male/female face flanges. When calculating the assembly bolt load, the reduced stability due to the reduction of the
σϑ value must be taken into consideration. The σV value is not
affected.

A1

Profile

A1

A1

FA
1 mm

Gasket limiting values
A1

A1

RivaThermSuper plain
sheet metal

RivaThermSuper
tanged sheet
metal

RivaThermSuper-Plus

RivaThermHD

50
100

50
100

50
100

50
100

25
50

50
100

50
100

50
100

50
100

35
80

30
60

15
90

2
15

35
60

10
120

20
140

20
160*

20
290*

-

-

-

-

-

10
110

20
120

20
140*

20
260*

ϑ

* Values measured in accordance with DIN EN 13555 at a 20mm gasket width

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

16

A1

FA / 1.4541

A1

Rubber

A1

PTFE

A1

FA
2 mm

Recommended max. roughness
from 50
µm
of flange surface
to
100
σv
Surface pressure
40
N/mm2
σϑ
limits for 20 °C
100
σv
Surface pressure
N/mm2 σ
limits for 300 °C
-

F1

FA
1,5 mm

Materials

Flat gaskets made from graphite, fibre, PTFE, elastomer