while the lower will corrode more, as seen in sacrificial anodes. Particular areas of stress along the metal's surface area will face corrosion more quickly because that metal is more active than the rest of the unstrained metal. Other environmental factors contribute to corrosion such as pH, salt concentration, and oxygen concentration, along with the velocity of the water and temperature.
How Corrosion Occurs
Corrosion can occur in two general ways; over the entire surface of the metal (Generalized Corrosion), or in local spots or areas (Localized Corrosion).
Generalized Corrosion: Typically never happens, aside from in acidic conditions. This uniform corrosion over the entire surface of the metal is rare and leads to overall thinning which has little effect outside of fatigue and stress conditions.
Localized Corrosion: The most common, and most detrimental, form of localized corrosion is pitting. Pitting is when the attack happens in one single location on the surface and creates a pit, or small cavity, in the metal. This type of corrosion attack is hard to prevent, engineer against, and often times difficult to detect before structural failure is met due to cracking. Pipes are often compromised due to pitting.
Corrosion can be prevented through using multiple products and techniques including painting, sacrificial anodes, cathodic protection (electroplating), and natural products of corrosion itself.
Painting: The paint forms a barrier between the metal and the environment, namely moisture.
Sacrificial anodes: Utilization of a metal lower on the Galvanic Series to be attacked first, instead of the metal in use. The sacrificial anode can be replaced as needed.