HYDROGEN ABSORPTION AND ITS PREVENTION OF TITANIUM IN A SIMULATED DESCALING ENVIRONMENT IN A DESALINATION PLANT

In a desalination plant constructed with titanium (tubes), copper alloy (tube plate) and steel or Fe-9% Ni alloy (sacrificial anode), the most preferred condition of acid dosing for descaling seems to be sulfamic acid solution containing IBIT (trade name of Asahi Chemical) as an inhibitor, from the point of view of prevention of titanium, copper alloy steel and Fe-9% Ni alloy against corrosion and hydrogen absorption. In this case the conditions should be kept in the following range: Concentration of sulfamic acid, 1-4%; temperature, under 60 degrees C; and concentration of IBIT, approximately 0.2%. A 4% H2SO4 With 0.5% HNO3 or IBIT solution can also prevent the corrosion and hydrogen absorption of titanium, but operation conditions for descaling (temperature, operation time, etc.) must be strictly controlled in this case because the corrosion rate of Cu-Ni alloy and steel are higher than that in sulfamic acid.