CATHODIC PROTECTION OF HEAT EXCHANGER
Have you heard of galvanic corrosion?
Have you heard of Cathodic Protection?
This is the photo of cathodic protection done inside a heat exchanger.
What is Cathodic Protection?
The more noble material (Cathode) is protected by sacrificial corrosion of the more active material (anode). Here in the picture the white block is of zinc and is called a sacrificial anode. This is to protect the heat exchanger from galvanic corrosion.
Heat exchanger's are susceptible to galvanic corrosion if the tube material is different from the tube sheet and/or baffles, in the presence of an electrolyte (Process Fluid)
In this picture, the zinc anode is corroded and the tube sheet is protected.
This picture, is taken during an annual
shutdown of the plant. During the shutdown, the corrosion rates are evaluated,
the tubes are cleaned and hydrotest is done to identify the leak's if any.
Tubes, whose thickness are less than the
required (due to corrosion) or leak during hydrotest are plugged before
reinstalling the heat exchanger back in operation.
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