PTFE envelope gaskets are used for a number of different applications. Depending on the construction (insert) they are suitable for use in many sectors.
The combination of a PTFE envelope and soft material / corrugated ring inserts provides high-level chemical resistance plus a wide range of applications.
For example, the sealing system PW-I [PTFE-enveloped gasket (TFM ™ 1600) with lathed, inner diffusion barrier and corrugated ring (in 1.4571 stainless steel) as insert] has been specially designed for use in steel flanges.
Optimized design of stainless steel corrugated ring and the PTFE-envelope allows this sealing system to be used under simultaneous 40 bar pressure and 200°C temperature.
The report of tests carried out by the German Technical Inspection Association (TÜV-Süd) are available.
Other combinations such as PTFE-enveloped gaskets with graphite inserts (SIGRAFLEX ® EMAIL) have also proven their application, particularly in enamel flange connections.
Conditions which are often met within the enamelled area of sealing surfaces such as very aggressive media, low seating stress, unevenness and distortions in the flange sealing surface etc. make high demands on the sealing system which cannot be met by using a single-material gasket.
The constructions and materials as well as the dimensions and properties of the gaskets are optimally adjusted for use in enamelled connections. The actual sealing function itself is taken on by the Dyneon TFM ™ 1600 envelope, a PTFE with modified molecular chain which displays excellent sealing properties.
A 3/4 mm-wide inner diffusion barrier prevents cross-sectional diffusion.
The excellent recovery rate of our envelope-gaskets with SIGRAFLEX EMAIL inserts compensate the cold and hot flow which is typical for PTFE (and which is lower in Dyneon TFM) as well as losses in stress load. It increases the blow-out resistance of the gasket via integrated stainless steel foils .
The properties of our envelope-gaskets with SIGRAFLEX EMAIL inserts complement one another perfectly.
As a further measure against bursting and blow-out, the system has been provided with a stainless steel corrugated ring insert covered by two SIGARFLEX EMAIL inserts which improve their compression and recovery rate.
The described constructions are also available in other material combinations as see below.