![]() ![]() Here’s the equation we’ll use to calculate the current output needed to protect our embedded steel structures:į: anode factor is 1.90 for a 42lb long shape 3″ x 3″ x 72″ magnesium anode First things first, we need to figure out how much current (or electrons) should flow from each anode. So, picture this: we’re setting up a solar farm, and we’ve got 378 steel stanchions that need protection from corrosion. Cathodic protection calculation for a solar farm In a nutshell, cathodic protection comes into play when the environment around a metal acts as an electrical conductor. As for submarines, this ingenious technique lets these underwater behemoths stay submerged safely for extended periods. Reduction: Your water heater and submarinesįun fact: your water heater and submarines use cathodic protection too! Just replace your water heater’s sacrificial anode every few years, and it’ll last way longer. ![]() We reduce water and oxygen into, adding those extra electrons – ’cause they’ve gotta go somewhere, right? Instead of transforming Fe ions back into solid Fe, we get a whole different reaction. Now, let’s say iron hasn’t rusted on the ship’s hull. If iron has oxidized on the ship’s hull, the following chemical reaction shows the Fe ions capturing the two electrons from zinc, giving us solid iron again, which is exactly what we want: The electrons cause ferrous ions to revert to solid iron. Moreover, the incoming electrons help restore the protected metal by reducing any oxidized parts and returning them to their original state. These electrons flow to the metal being protected, forcing it to become a cathode. It oxidizes in the electrolyte (soil or ocean, for example), generating electrons. The sacrificial anode, also known as the galvanic anode, sacrifices itself to protect another metal from corrosion. For instance, when protecting iron, you would use a metal that is more reactive than iron, such as zinc or magnesium. A more reactive metal loses electrons more easily, forming ions. There are two main cathodic protection methods, each with its own perks and drawbacks in real-life situations: Method #1: Sacrificial anodeĪ sacrificial anode is a metal that is more reactive than the metal it is protecting. This is done by passing electrons to the metal in need of protection, like a massive steel pipe or a ship’s hull. How does cathodic protection prevent corrosion?Ĭathodic protection is a nifty technique that stops corrosion by turning all the active (anodic) spots on a metal surface into passive (cathodic) ones. The dipped half turns into the anode, while the other half with high oxygen concentration becomes the cathode. Picture a pipe half-dipped in water with low oxygen concentration. For example, a single pipe can have both an anode part and a cathode part. ![]() These differences can be large, leading to non-uniformity on the metal surface. ![]() A short Standard Reduction Potentials table is available from the HandbookMenu, but you may also click the live link to see one.Important Note: The two different metals can be separate metals, or a single piece of metal with variations on the surface. These values are usually tabulated in handbooks. Reduction potentials of standard cells have been measured against the SHE or other standards their potentials are measured. Ideally, for every redox couple, there is a reduction potential. \( \newcommand\) ions are less ready to accept electrons than hydrogen ions. ![]()
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