What is anodic corrosion protection?
Anodic corrosion protection is an electrochemical corrosion-control method for active-passive metals (carbon steel, stainless steel, titanium) in strongly aggressive environments, such as sulfuric or phosphoric acids and caustic soda, as well as in liquid fertilizers.
How does anodic protection differ from cathodic protection?
Anodic protection differs from cathodic protection not only in DC current polarity, but also in use: Cathodic protection is mainly used to protect buried pipelines from the outside, while anodic protection is used to protect technological equipment, such as tanks or coolers from the inside.
Does it mean that protected equipment is electrified?
Protected equipment is connected to very safe DC source with very low voltage (approx. 1V) and is controlled by advanced electronics. All electrochemical processes take place inside the apparatus and nothing is distinguishable from the outside. No electrical injuries have occurred during our 40 years of dealing with anodic protection. It is not physically possible at all.
What constructional material should the protected equipment be made from?
The metals have to be active-passive: Carbon steel, stainless steel, and titanium only.
What chemicals is anodic protection suitable for?
It has to be a conductive solution or melt, usually sulfuric or phosphoric acids and caustic soda and liquid fertilizers as well. Another story is anodic protection in chemical nickel plating solutions, where it doesn't serve as corrosion protection but is used to inhibit nickel deposition on the bath's walls and to cause nickel to be deposited solely on the metal parts to be plated.
What are the advantages of anodic protection?
Anodic protection reduces regular corrosion rate (< 0,1mm (4mils)/year) and eliminates irregular corrosion (pitting corrosion, corrosion cracking). Thus, AP is economically very advantageous and saves investment costs. It enables to replace expensive alloys by common stainless steel or stainless steel by carbon steel. It improves product quality and purity, which remains “technically pure.“ AP enables safe heat recovery from acid coolers, where heat is otherwise lost in huge amounts.
What applications of anodic protection not stated in Reference List could also be possible?
Stainless steel in phosphoric acid containing chlorides and in oxalic acid as well; carbon steel in ammonia solutions.