Page 12 - Pipelines

Protection of insulating

joints and flanges

Insulating joints and flanges are used to electrically (galva-
nically) isolate cathodic protection pipeline systems against
system earth or to divide high voltage interfered pipelines
into individual pipeline sections. Cathodic protection systems
are electrically isolated until the dielectric strength of the
insulation of the insulating joint / flange is reached. The
dielectric strength of insulating joints can be exceeded by
overvoltage resulting from a lightning strike to exposed parts
of a pipeline system or the effects of short-circuit currents of
parallel high-voltage lines. This may lead to sparking, leakage
or destruction of the insulating joint. Isolating spark gaps for
use in hazardous areas (ExFS) with adequate and correctly
installed connection systems protect this insulating clearance
against transient and temporary overvoltage. In addition,
they discharge the overvoltage energy in a dangerous
potentially explosive atmosphere without sparking.

The following protection goals can be achieved with the
DEHN protection solutions:
• Protection of the insulation in case of temporary and
transient overvoltage
• Explosion protection by tested and non-sparking connec-
tion systems as well as ATEX and IECEx approvals
If the ExFS is incorrectly installed, the insulation may be
destroyed. This may entail high costs particularly in case
of underground insulating joints. Therefore, DEHN offers
product support and adapted protection solutions, for
multiple applications. L s = 300 ... 2000 mm
coaxial cable
L = 500 ... 5000 mm
pipeline

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