The piping of our heat exchanger in 316 SS (1" was blocking by the deposit of Fe2O3 (solid) inside the pipe. Does any expert can suggest me a product to remove by dissolve the Ferro oxide (Fe2O3) and clean up the heat exchanger.
Formic acid is commonly applied to clean exchangers, on-line, in-situ. If you can take her down, you can probably get away with using HCl so long as the temperature is not high. It should remove it rather quickly I would think.
iron ions, in general, can be found as precipetated ions within 9 < PH < 1.8 under PH outside this range iron ions became soluble ... I do not know the material that flows through ur HEX but if u can manipulate PH.. this may help...
I have used nitric acid solutions for cleaning 304 & 316 SS HXers, usually 25-45 vol. % since this was readily available (Type VI Passivation solution per QQ-P-35C). This has the advantage of not attacking the metal. Also, after removal of the Fe[sub]2[/sub]O[sub]3[/sub] (acid comes out clean), passivate with clean nitric solution and then rinse the HXer.
HCl will work quite well, but you should use an inhibitor. As Fe[sub]2[/sub]O[sub]3[/sub] dissolves in HCl, the solution becomes more corrosive towards the metal.