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Environmental Stress Cracking |
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Environmental stress cracking (ESC) is a well known but not always
understood phenomenon with plastics. ESC occurs in plastic-lined parts
when the plastic liner is exposed to chemical liquid while under
mechanical or thermal stress. ESC can lead to failures at stresses
below the tensile strength of the material. In some instance, the
presence of a contaminant may act as an accelerator. For example,
iron or copper contamination in concentrated sulfuric or hydrochloric
acid can result in stress cracking of polypropylene liners. All
plastics, including PTFE, are known to be susceptible to ESC.
The occurrence of ESC is hard to predict. It is dependent on the
process chemistry, operating conditions, physical piping system
layout and quality of field fabrication of the piping system. In the
chemical resistance tables, certain
chemical/liner ratings are
linked to this document. This indicates the liner is contact with
that specific chemical may be susceptible to ESC. This does not mean
the liner in question will not work, but additionally data must be
gathered to ensure that the liner is compatible with the chemical. If
the chemical in question is suspected of causing ESC with a particular
plastic liner and testing cannot be done to determine suitability,
choose an alternative liner from the chemical resistance tables.
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English. This translation is intended to provide a general idea of the
page's content, and is not guaranteed for accuracy."
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