Page 3 - Pipelines

DEHN protects pipelines

from overvoltage interfe-
rences

Pipelines operate under high pressures. If they are additio-
nally loaded, the pipeline material, for example steel, quickly
reaches its limit. In extreme cases, heavy corrosion can cause
failure in the pipeline, resulting in leakage which may cause
enormous material and environmental damage. Therefore,
the condition of the pipeline must be continuously monito-
red during operation. Particularly any kind of corrosion must
be immediately spotted throughout the complete pipeline.

Passive corrosion protection is achieved by coating and
painting the pipeline. This, however, is not sufficient
since even small defects in the coating quickly cause local
corrosion effects (electrochemical corrosion) in the pipeline.
Moreover, a.c. corrosion can occur as a result of a.c. voltage
interference. Active cathodic corrosion protection must
therefore be combined with passive corrosion protection.
Cathodic corrosion protection requires that the pipeline
is continuously monitored. To this end, the voltage level
along the pipeline is detected at the relevant test joints
and adapted to the intensity of the protective current, if
necessary. In addition, sudden pressure drops (leakage) is
identified by continuously measuring the pressure. Quantity
measurements are also frequently carried out to compare
the quantity at the beginning of the pipeline with the
quantity at the end of the pipeline and trigger an alarm if a
difference is identified. In order to specifically protect these
high availability measuring systems, DEHN offers protection
solutions for use in potentially explosive atmospheres which
are certified according to ATEC* / IECEx**.
Due to the extended surface of pipelines, there is a high
risk of lightning effects and overvoltage interference,
for example caused by nearby high-voltage and railway
systems. Since the pipeline is galvanically connected to the
cathodic protection rectifier, lightning and surge protection
measures are required to discharge all overvoltages. The
aim is to prevent fire or failure of the cathodic protection
rectifier. To this end, DEHN offers coordinated solutions

* ATEX Guidelines: Guidelines of the European Union on Explosion Protection („ATmosphère EXplosibles“)
** IECEx Standards: Standards of the International Electrotechnical Commission on Explosion Protection

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