Surface Protection sector - Hot condition galvanization
Technological process of the hot dip galvanization
The galvanization reaction happens when the steel is chemically cleaned.Therefore during the preparatory work this has to be taken into consideration.
In general the success secret of the steel coverage successfully is its preparatory phase. It is important first before the hot dip galvanization the part which will be galvanized should not be with oil, corrosion or painted as such for the removal of these there has some work to be done.
Ordinary practices is first to remove all the oils by cleaning it with basic acids or acids for removal of oils by dropping it inside. After this the part/metal for galvanization is cleaned with cold water and after it is dropped into chloride acid which is in the same temperature as the room through which the rust and welding remaining are removed.
Big welding remaining, paints and oils will not be removed through these diving/droppings therefore previously these must be removed. After this the process of dive of the steel in galvanization is done.
Usually this procedure is conducted as follows: 30%tnigalvanization-amoniujum-hlorid in 65-80 Celsius degrees but some galvanizations can use also flow.
These diving remove also the last oxides which have remained in the steel which allows the melting and attaching of the galvanization in the metal.
Hot dip galvanization procedure
When steel is cleaned it dives in the galvanization (usually at 450 Celsius degrees) because of the metallurgy between galvanization and steel which is usually a parabolic relation with the time and for this reason the reaction range is very fast and the galvanization tube is not very stabile. The main layer is formed in that time, after that the reaction is slowed and the thickness of the coverage of galvanization does not increase much. The usual dive lasts around 4-5 minutes but it can last longer base on the thickness of the steel and unreachable places where time is needed for the process to be finished. During the galvanization removal from the galvanization tube through which a layer of the galvanization is removed as after it is cooled a bright shining is seen which is typical for a galvanized metal.
After the hot galvanization the metal should be cooled with water or air. Atmospheric conditions which are in the room of galvanization like the temperature, humidity or the air quality do not affect the quality of the galvanization and metal galvanized which is not the case for the painting of the metal as these parameters have a big impact.