Question

Briefly explain why placing a PVC pipe nipple between a black iron water pipe and a copper pipe inlet to a hot water heater can prevent corrosion. Use galvanic corrosion cells and activity series as the basis of your discussion

Answer 1

As we know that corrosion is a process of destruction of a metal. It is of many types such as galvanic corrosion, metallic corrosion, Creve corrosion, bent corrosion, waterline corrosion, differential aeration corrosion etc.

Here, the iron and copper metals are good electric conductors and are separated by non conducting PVC material. If they are in direct contact, they form a circuit where establishment of dry metallic type circuit takes place. Since Fe is placed above the Cu in electrochemical series, acts as anode under go corrosion.

Fe -----------> Fe ^+2​ + 2e-

This is prevented by avoiding direct between Fe and Cu. This is done by using PVC material or any other non conducting material.