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Immersion pickling systems

Pickling (metal treatment with an acid solution) is typically used for the pretreatment of rusted steel and for activating the steel surface prior to applying a nickel flash for a so-called direct-on white enamel process.

Pickling may be done by means of immersing products into a series of tanks or by spraying inside a conveyorized corrosion-resistant tunnel. This second option is rarely selected due to significant investment & maintenance cost.

At immersion pickling systems products are typically placed into stainless steel baskets and then transported from one tank to the next by a manually operated hoist or by a handling robot.

Below pictures of both material handling solutions.

 

 

Automatic immersion pretreatment system

with robot.

 

Manual immersion pretreatment system

with manual hoist



Typical pretreatment stages for a direct-on white enameling process

Stage

Description Temperature (Celsius) Duration (minutes)
1 Alkaline cleaning 80 - 90  
2 Alkaline cleaning 80 - 90  
3 Alkaline cleaning 80 - 90  
4 Hot water rinsing 70 - 80 2 - 5
5 Cold water running rinsing room temperature 2 - 5
6 Sulphuric acid 70 - 75 8 - 15
7 Cold water running rinsing room temperature 2 - 5
8 Nickel replacement 70 - 75 5 - 6
9 Cold water running rinsing room temperature 2 - 5
10 Cold water running rinsing room temperature 2 - 5
11 Neutralizing 70 - 80 3 - 5
12 Drying    

NB : Depending upon the type of contamination, low temperature alkaline cleaners may be used.

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