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Pipework Corrosion - Galvanic Corrosion and Dielectric fittings

Galvanic Corrosion 


All metals have specific relative electrical potential. When metals of different electrical potential are in contact in the presence of moisture, a small electric current flows from the metal having the higher position in the galvanic series. This is called "galvanic action." Galvanic corrosion is a form of electrochemical corrosion that occurs when two dissimilar metals come together in the presence of an electrolyte to form an electrical couple, known as a galvanic couple. The more noble the metal, the less likely it will corrode relative to the other metal it is in contact with.

Galvanic corrosion potential is a measure of how dissimilar metals will corrode when placed against each other in an assembly. Metals close to one another on the chart generally do not have a strong effect on one another, but the farther apart any two metals are separated, the stronger the corroding effect on the one higher in the list. The list on this slide represents the potential available to promote a corrosive reaction, however, the actual corrosion in each application is difficult to predict. Typically, the presence of an electrolyte (i.e. water) is necessary to promote galvanic corrosion.  

A dielectric fitting offers a barrier between the pipes, breaking all galvanized current and preventing corrosion in the pipes. This helps in preserving the pipes and stopping the unintentional production of electricity, which could lead to damage brought by corrosive actions.  It is highly important as when iron and copper components are combined, galvanization may take place resulting in corrosion, and eventually, total failure of the pipe system.


 


Control Valve sizing & flow rates using Kv or Kvs values