PTFE-enveloped gaskets0 pages

PTFE-enveloped gaskets

In flange connections where there are high levels of chemical attack, PTFE flat gaskets are used. Due to the cold flow
affinity of unfilled PTFE, use is mainly made of PTFE composites and PTFE-enveloped gaskets which have increased
resistance to stress relaxation.
Because of their high chemical resistance and outstanding
sealing properties, PTFE-enveloped gaskets have proven
excellent when used at fluctuating pressures and temperatures ranging from -195 °C to +250 °C. Glass tubes, metalenveloped glass tubes and glass equipment from laboratory or pilot installations can be connected up as easily as
enamelled, coated or lined pipes and equipment in large
plants.
PTFE-enveloped gaskets are particularly useful with aggressive chemicals in the chemical industry, due to their high
resistant strength. PTFE is also physiologically harmless,
and so can be used in the food and pharmaceutical sectors.
Apart from their high resistance to chemicals, PTFE is also
extremely anti-adhesive. This non-stick effect means that no
material will adhere to the surface of the PTFE.
PTFE-enveloped gaskets consist of a stable gasket insert
and a PTFE envelope. Only high-quality, non-porous PTFE is
used for the envelope, so as to protect the insert against
chemical attack. The PTFE envelopes are open onto the
outer or inner diameter, or encase the entire insert, depending on what is required. The envelope is 0.5 mm thick and
therefore very stable. Lathed envelopes can be produced
with an internal diameter 2 to 4 mm thicker to provide greater
diffusion sealing.

Insert: Soft material flat gaskets
The insert is made of a graphite laminate or fibre sealing
material. With a graphite laminate insert, the gasket is also
suitable for use with plastic or GRP flanges due to its greater
conformity and softness.
Profile PF2 with a envelope that can be supplied as a
lathed or shaped envelope, depending on the size of the
gasket

05

Profile PF3 with a envelope with a reinforced internal
diameter.
Profile PF18 with a envelope that is punctured without
cutting.
Profile PF21 with a lathed envelope.
PTFE-enveloped gaskets fulfil the requirements of the TA
Luft having regard to clause 3.3.1.4 of the VDI Guidelines
2440.
Gasket profiles
Profile

Cross-section

PF2
PF3
PF18
PF21

For dimensions see the section “General Dimension Tables”.

Gasket limiting values
Profile

PF2 to PF21
Graphite
laminate
2 mm

Fibre
sheets
2 mm

Materials

50
100

50
100

20
90

15
60

σϑ

25
80

-

from
to

-195
250

-100
150

Recommended max. roughness
from
µm to
of the flange surfaces
σv
Surface pressure
N/mm2
σϑ
limits for 20 °C
Surface pressure
limits for 250 °C
You can find gasket characteristic values in accordance with
EN13555 on our homepage at www.kempchen.de

Temperature range

N/mm2
°C

σv

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

PTFE-enveloped gaskets

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