Underground Corrosion Control 3:4
CP 1 – Cathodic Protection Tester Course Manual
© NACE International, 2000
02/01/05
dew point must be checked against the manufacturer or consultant’s
specifications. This is to ensure the surface is being prepared and the
coating is being applied in an atmosphere conducive to proper coating
performance.
Maintenance Inspections
While detailed inspections need to be made by the proper level Certified
NACE Coating Inspector, cathodic protection personnel may be called upon
to make an inspection of exposed coating. This can be done visually, looking
for signs of disbonding, damage, checking, cracking, chalking, and other
deterioration.
The purpose of this inspection is to determine the condition of the coating to
see if any reconditioning is required. If a poor coating is found, it may be
necessary to excavate more of the pipe to see how far the deterioration exists.
Electrical Isolation
Electrical isolation devices may be used to separate different metals or
other anodic and cathodic components of a corrosion cell. Insertion of
dielectric material interrupts the electronic portion of the corrosion cell,
thereby isolating the anode from the cathode.
Electrical isolation is also an important part in cathodic protection work
and will be discussed in some detail in subsequent chapters.
Environmental Control
In aqueous environments, various chemicals may be introduced to the
water or process stream to reduce its corrosivity to the exposed metal.
Similar measures are used in pipelines carrying corrosive gasses or
liquids.
There has been some application of environmental control to
underground facilities, but success has been limited. Effective use of
environmental control is basically limited to liquids in confined spaces
such as piping, boilers, and tanks.
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