Protection for Natural Gas Installations Against the Corrosive Effect of Mercury by a Chemical Nickel Coating

Aluminium in contact with mercury is degraded by amalgamation. This phenomenon is of interest in LNG (Liquefaction of Natural Gas) operations. Where the mercury – either contained in natural gas or from other sources – may be introduced into the system and come into contact with equipment made of aluminium or aluminium alloys (for example, cryogenic exchangers, LNG storage tanks and cargo tanks). Various methods to remove mercury from gas streams are used to trap mercury upstream installations in question by the means of specific absorbers. However, this trapping is not total, and corrosion by mercury even with the state of traces always threatens. In this context, and for the intention of preserving these installations even in the presence of corrosive metal, we recommended a solution which consists in applying a metal chemical nickel coating using the sodium hypophosphite like reducer.