b. Inorganic fouling
The most commonly used cleaning agent for scaling problems is acid.
Mineral acids have a strong ability to dissolve the scales. But these can also corrode the steel
and copper material in the system. Such acids include sulfuric acid, hydrochloric acid and
nitric acid. However, these acids will also attack/corrode the stainless steel, gaskets and
copper parts.
Organic acids are weaker than the mineral acids in the corrosive properties but still able to
dissolve the scales. This make them ideal when used to clean the BPHE.
Such acids include phosphoric acid, formic acid and acetic acid. Usually, this acid is used in
combination with other chemicals to enhance the cleaning capabilities.
Whatever type of acids used, care must be taken in handling the chemical. A concentration 2
to 5% should be mixed and circulated into the system. An additional inhibitor
chemical may be
added, if necessary, to diminish the corrosive action onto metals.
Refer to the chemical manufacturer recommendations on the required dosage to use. Upon
completion, flush with lots of clean water to remove any excess acids. Depending on the
directions of usage, some may require neutralization and passivation after cleaning.
Example of Cleaning chemicals:
a. AIfaCaus : sodium hydroxide for cleaning of organic fouling
b. AIfaPhos : phosphoric acid (organic acid)
c. AIfaCarbon : formic acid (organic acid)
d. Kaloxi : citric acid, phosphoric acid
e. P3-T 288
f. Nitric acid (1 %) + P3-stabicipNA (inhibitor)
Section 9 Page 110
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