Carbon steel, stainless steel, alloys with chrome or P91/92
Loose iron oxides (rust), very light oil, grease and atmospheric dirt & loose silicates.
An alternative method for cleaning a steam boiler is to boil out the water side prior to steam blowing. The primary purpose of boiling out is the removal of oil, grease and silicate compounds. However, this cleaning method does not remove welding skin, mill scale and annealing skin. To remove this, a pre-commissioning cleaning is required (acid cleaning).
This cleaning method is carried out according to VGB guidelines and depends on the type of boiler, the amount of oil & grease present and the criteria of the (end customer). Generally, a method is chosen from the following two options:
Weak alkaline boil-out
This method is often used with steam boilers, where smaller amounts of oils, grease and other organic contaminants are expected.
Strong alkaline boil-out
This method is often used with steam boilers, where larger quantities of oils, grease and other organic contaminants are expected. Higher concentrations of hydroxides are used.