What Does Denickelification Mean?
Denickelification refers to an occurrence of corrosion where nickel is extracted by leaching from its alloys. This process occurs in copper-nickel alloys that have undergone significant exposure to seawater or other aquatic environments.
Corrosionpedia Explains Denickelification
The primary cause of the waterside failure of condenser tubes has historically been identified as plug-type denickelification. This corrosion type involves the creation of an active cell that dissolves the alloy and redeposits copper. Once the denickelification is started it can be self-propagating due to the limited supply of oxygen.
Denickelification has empirically been observed in higher-nickel content copper-nickel alloys that are used primarily for refinery applications. In these applications, hydrocarbon stream condenses at temperatures above 300°F (149°C). Due to the significant temperatures and moisture concentration of such processes, hot spots develop in the tubing of associated equipment as a result of fouling and thermogalvanic differences that arise. Hot spots are the most severe representation of denickelification.
The solution to hot spots is frequent cleaning to remove built-up deposits or increasing the flow rate to avoid deposits.