Underground Corrosion Control 3:5
CP 1 – Cathodic Protection Tester Course Manual
© NACE International, 2000
02/01/05
Inhibitors
Inhibitors are added to liquids to change the characteristics of the liquid
or to form protective films on the surface of the metal. Some inhibitors
form films on anodic or cathodic spots along the metal surface. Some,
such as those used in potable water systems, lay down a protective film
over the entire metal surface.
Oxygen, which plays an important role in the corrosion reaction, may be
controlled by the addition of oxygen scavengers. This is especially
important in the treatment of boiler water.
Adjustment of pH
The pH of water affects its ability to precipitate out a protective scale.
Control of pH is used to create a water that will not be aggressive to the
metal piping and vessels it contacts.
Maintenance of Environmental Control
Inhibitors and other environmental control must be applied at the proper
dosage and must be properly maintained. Corrosion prevention is
dependent on the concentration of the chemicals in the liquid, and
regular testing and chemical control must be initiated.
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