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Control Parameters in Pickling of Hot Rolled Coil

We have a newly pickling line for carbon steel, Continuous, with HCl bath, the main challenge is the quality of the final product. How can we apply the standard method for judgment or reference for comparison the defects?

Also what is the parameter for acid regeneration plant control?

Nabil Sahlab
ANSDK - Alexandria, Egypt
2000

For a newly built line like yours , you need to take data of roughness of pickled coil in a regular basis. Ideally this value should stay around 1Ra or less then it. This will determine your pickling condition . Then you need to keep track of acid concentration of each tank in a regular manner to established usefulness of acid. From the lab report of pickle liquor one can established the pickling condition, Fe ++ ion should stay within the value of 120 gm /liter. Any thing beyond this will always indicate over pickled condition. Coil appearance after pickling always indicate the pickled condition, if coil looks silver white then it indicates over pickling if coil shows a dark appearance then it indicates an under pickling.

Ashis Kumar Satpathy
- Jamshedpur, Jharkhand, India
2004