Summary for sulfuric acid pickling hazards Discussion
Personnel hazards of pickling in sulfuric acid are addressed mainly through proper fume control. Tamer EL-SHAHAT asked about the disadvantages of 12% sulfuric acid at 35 °C for steel pickling before galvanizing, and whether a scrubber unit would create dangers. Ted Mooney, P.E. replied that a scrubber is necessary and that, if properly used, there should be no danger from it. He added a practical and cost-oriented suggestion: use an ordinary 12 micron horizontal blade-type mist eliminator at the far end, connected to the fan, with plastic ducting. He said a stainless 316 fume hood might work, but strongly warned not to use fiberglass ducting and recommended PVC instead. The thread is brief and does not detail other process disadvantages beyond the need for safe ventilation and fume handling.
Q. Please I need to ask about the disadvantage of sulfuric acid pickling at concentration of 12% and at a temp. of 35° C and encapsulated area of steel pickling for galvanization and if there is scrubber unit installed what are the dangers of these units?
Tamer EL-SHAHAT
– Zagazig, sh, Egypt
2003
A. Hi Tamer,
Sorry, but I don’t quite understand all your points.
Yes, a scrubber is necessary. No, there should be no danger if one is used. HOWEVER, from a practical and also a cost viewpoint, I suggest you use an ordinary l2 micron horizontal blade type mist eliminator … at the far end and joining to the fan.
You must use plastic ducting. You might well get away with using a stainless 3l6 fume hood. Don’t, DON’T use fibreglass ducting but use PVC (if you want to know why, then just ask!)
Does this answer your questions? If not, please come back.
Freeman Newton [deceased] (It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).
2003
A. Hi, Tamer.
I may not be understanding your inquiry correctly, and I apologize if so. But all industrial processes have dangers and I think the way to view it is to compare the process to the alternatives, and then to figure out out how best to ameliorate any dangers.
The metal must be pickled (acid dipped) and the only reasonable alternative would seem to be to use hydrochloric acid, and I’m not seeing how this would be healthier. So the next step is to capture the fumes, so they are not breathed by the employees, and then to scrub them before discharge to the atmosphere.
But the purpose of the scrubber per se is to clean the fumes before discharge, and the installation of a scrubber does not guarantee a safe environment for the workers. Rather, what helps the workers is making sure the fume hoods and exhaust rates are adequate, and that the work methods results in the least practical exposure to fumes. It is possible for the workers to wear exposure badges for a couple of weeks to monitor whether improvements are needed. God luck.
Regards,
Ted Mooney, P.E.
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June 2, 2012