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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.

Immersion pickling systems

Typical pretreatment stages for a direct-on white enameling process