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-----Pickling Alternatives
What alternate procedures exisit to pickling of carbon steel for scale removal? Environmental concerns are making it difficult to find vendors willing to pickle.
Aaron Tanzer- Orlando, Florida, USA
2003
Mechanical descaling is often performed using a variety of media: blasting (sand, grit, bead, etc.) belt grinding/sanding wire wheel/brush Contamination is an issue, so take care to clean after descaling.
Toby Padfield- Michigan
2003
2003
Alkaline pickling or descaling is a common practice. There are many proprietary and cookbook products. The benefits are minimal hydrogen embrittlement, little pitting or etching, minimal smut formation, very little metal is removes and the finished surface is much cleaner than those prepared by acid pickling.
The down side is higher temperatures are required using high concentrations of caustic, solutions re typically more expensive than simple pickling acids and they are harder to control and are not as aggressive against oxides as acids are.
The mix is usually caustic at 12 oz./gal. with an equal amount of potassium permanganate
⇦ on
eBay or
Amazon [affil link] at 160 °F for 30 minutes. You can also find formulae with gluconate, EDTA or cyanide for the boost. It will sure make waste treatment a challenge.
Chemithon Surface Finishing - Seattle, Washington
One step de-scaling, pickling and coating can be performed by an environmentally safe, non-hazardous product Picklex® [affil link]®, with no waste disposal. It prepares the surface for welding & finishing. This is an alternative process from International Chemical Products, Inc.
Ranjit Sen- Huntsville, Alabama
2003
I can not quite buy Ranjit's "No Disposal" statement. It cannot function forever with additions. Eventually it will have to be dumped. I would be very surprised if there was not enough of something in the dissolved material that would make it against the rules to dump without treatment. If it were a plating facility, it could be run thru the waste treatment system , but that has to have at least the solids sent to a certified landfill or be exempted in most cases.
James Watts- Navarre, Florida
2003
It is true that nothing can function forever without dumping, but Picklex® [affil link] got really impressive reviews by EPA and Battelle in a very long article in the April issue of P&SF.
Ted Mooney, P.E.
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2003
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