cpp – Process technology for the chemical industry 01.2019

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PLANTS, APPARATUS, COMPONENTS
Picture: Mulderphoto – Fotolia.com
Fig. 1: The Chem XP material family should meet the high requirements in process plants
Highly fluorinated materials for chemical processing facilities
Strong performance
Fluoro rubber (FKM) is considered the standard material for seals in processing
facilities, yet it offers only limited resistance to acids, bases and solvents. For
demanding applications, perfluoro rubber (FFKM) has been used until now, although
it is significantly more expensive than FKM. Freudenberg Sealing Technologies has
developed a new family of materials called Chem XP, which fills the gap with a good
balance between performance and cost.
The seals used for equipment in the
chemical process industry today are mainly
made of fluorinated materials (Figure 1).
The amount of fluorine and the composition
of the formulation affect the cost of the
material on one hand and the resistance of
the various fluoro elastomers to acids, bases
and solvents on the other. Fluoro rubber
(FKM) is widely employed as a standard
material in chemical processes. In many applications,
this material is a suitable choice
for O-rings, formed parts and diaphragms.
For example, standard FKM is distinguished
by its high resistance to mineral oils and
other hydrocarbons. However, its resistance
to certain acids, bases and organic solvents
is comparatively low. If FKM comes into
contact with increased concentrations of
these media, they can attack it chemically
and cause it to swell, leading to significant
changes in its mechanical qualities. In this
event, the material foundation must be selected
and combined differently, so that it
can withstand chemical attack. In especially
demanding applications, perfluoro rubber
(FFKM) is the preferred material because it
offers excellent media resistance due to its
complete fluorination. Unfortunately, in the
light of factors like its elaborate production
process, FFKM is very costly and the extremely
high level of performance it
achieves is not necessarily a requirement.
Good balance
With this in mind, Freudenberg Sealing
Technologies has developed a new line of
materials called Chem XP, which fills the
gap and creates a good balance between
performance and cost. Its characteristics in-
56 cpp 01-2019