Anode beds are usually filled with which substance?

Anode beds are typically filled with coke breeze, a byproduct of the coking process in the steel industry. This material is used because it has the necessary properties to enhance the effectiveness of cathodic protection systems. Coke breeze has excellent conductivity, is resistant to corrosion, and provides a stable environment for the anodes.

The use of coke breeze ensures that the anodes can efficiently discharge electrons into the surrounding electrolyte, which is crucial for protecting structures from corrosion. Its granular nature allows for good packing and minimizes the resistivity of the surrounding soil, promoting more effective current distribution.

In contrast, gravel, sand, and coal do not possess the same level of electrical conductivity or stability as coke breeze, making them less effective in supporting cathodic protection systems in anode beds. Gravel and sand can also retain moisture but might not facilitate the optimal electron transfer needed for protecting metal structures. Coal, while a carbon source, lacks the specific conductive properties required for effective anode bed applications.