The photo is from existing 345kV and 500kV guyed tower foundations. Structures on the left are on a new 500kV circuit and those on the right are on a 20 year old 345kV circuit.
Structure-to-soil potential measurements on guyed anchors and tower foundations on the 345kV circuit showed that cathodic protection had failed on some of the towers due to incompatible selection of anode material for the soil environment. Other structures were not protected simply due to exceeding the useful design life of the anodes.
Recommendations were made for replacement anodes, where necessary on the 345kV circuit. A comprehensive cathodic protection design was furnished for the 500kV circuit.[...]
The most common types of corrosion
Corrosion is one of the most common problems in just about every industry. It can affect household items, vehicles, heavy equipment, and entire industries, such as the pipeline industry and the manufacturing industry. Corrosion is commonly called rust, but there are many unique types of corrosion, each of which has different causes and cures. Learn about the most common types of corrosion with this brief guide.