45060

Can we use sodium silicate as stabiliser after cleaning with H2O2 [Egypt] 

May 5, 2007

We clean steam reboiler ( Carbon Steel) by using H2O2 Ph= 4 and the corrosion engineer suggest we should use the citric acid after finish the cleaning by H2O2. but i'm not sure about this suggestion so i recommend using sodium silicate after finishing the cleaning

please if you have an idea about this, tell me your opinion and the reference if its available.

your cooperation is highly appreciated

Ahmed Abdel Aziz
laboratory chemist - Cairo, Egypt

Do an ammonium citrate passivation of the boiler (use Google to find a written procedure).

The cleaned boiler is filled with dilute citric acid solution, the pH is raised to 9-10 with ammonium hydroxide, and an oxidizer such as H2O2 or sodium nitrite is added to raise the ORP to 600-1100 mV. The heated solution creates a very thin film of magnetite Fe3O4 on the steel surface.
After treatment, drain quickly and refill the boiler with properly pretreated feedwater. I wouldn't use silicate; it may cause scaling problems.

Ken Vlach - Goleta, California