Final answer:
The reference material describes the use of sacrificial electrodes for corrosion protection but does not specify the common welding electrodes for industrial piping. Common types such as E6010 and E7018 are typically used in the industry for various qualities such as penetration and finish.
Step-by-step explanation:
The two most common electrodes used when welding industrial piping are not explicitly specified in the provided reference information. However, typically in the industry, electrodes such as E6010 and E7018 are commonly used. The former is often used for its deep penetration and ability to weld through rust, oil, and dirt. The latter is preferred for its ease of use and smoother finish.
The reference material provided discusses sacrificial electrodes like magnesium, which are used for corrosion protection in underground pipes or tanks. This process involves connecting a magnesium rod to steel objects; the magnesium, being more reactive, will corrode instead of the steel. This type of electrode is an example of how electrochemistry is applied to prevent corrosion in industrial piping systems, but it does not directly relate to welding electrodes used for joining metal sections.