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BLOG 7-Robert M. Woods      

Last blog was discussing a “pure” acid degreasing approach, using Phosphoric-acid based product such as Hydronet Base, Ricarica, and S.  There is another approach that can be used in some cases, with additives directly into the pickling acid tanks. Hydronet D is the name of our product that can be added directly into Hydrochloric acid tanks at the typical concentrations and temperatures used by North American galvanizers.

Acidic Degreasing – in the pickle tank

Without help, Hydrochloric and Sulfuric acids are not very effective at removing dirt.  Hydrochloric acid in particular is poor at lifting greases, oils, chalk, and most other soils.  Sulfuric is a little better, but more because it is heated AND attacks scale and rust by “blowing off” the top layers of rust IF it can penetrate the cracks in the scale. 

Generally, degreasing with an additive in the pickle tanks is not as effective as a stand-alone tank with SB Clean-Caustic or Hydronet Base or S; however, for lighter duty cleaning where the incoming steels have low levels of oil or grease, this approach can be effective.  If used in combination with a separate stand-alone cleaning tank, the added cleaning power in the pickle can be a “clean-up” for anything the previous tank missed, or for when for one reason or another that tank is skipped. 

The approach using Hydronet D enables the Hydrochloric acid to lift and disperse the oils and greases far better than the acid alone.  This is important, as the dirty surface inhibits the acid from doing its job—basically blocks the acid from reaching the rust and scale.  Adding Hydronet D to the tank can significantly improve pickling speed, and decrease defects due to poor cleaning/pickling.  This impact can improve how fast material can move through your plant; in combination with Ironsave inhibitor, the acid becomes more effective while leaving a cleaner, smoother steel surface.  Smoother surfaces mean less zinc pick-up overall, and less dirt carried in means less skimmings and defects. 

Hydronet D is not recommended for Sulfuric acid; the temperature combined with the sulfuric acid will damage the product effectiveness.  Sulfuric is, as mentioned, a little better at cleaning in any case; it also will slowly degrade oils and greases carried in, though it does sacrifice pickling power to do so.