Hot Rolled Steel Scale
Is there a simple chemical process to remove scale from hot rolled steel?
Yes, A dip in hot H2SO4 . Not something you would want in any good shop.
Let china do it, I dont care if they live in a toilet at all.
Most any mineral acid will loosen scale. If you have a couple of months bury it and let the soil acids and the ferrophagic bacteria do the job. Most of the scale will power wire brush off - but not all.
I prefer a one part muratic acid to 10 parts water pickle. If you add the right inhibitor the acid won't attack the steel. A gallon will pickle maybe 4 square feet of steel. Most of the scale comes loose in tiny crumbs that forms a granular scum. Flush off the bare metal with a garden hose and wire brush the metal to get anything that's still stuck.
Then neutralize with a sprinkle of washing soda or Arm and Hammer dry laundry detergent, scrubbing it in.
Finally, treat the metal with Jasco Metal Prep to phosphate coat the surface and make it rust resistant. Dry and spray with a light preservative oil. Your metal will stay rust free for months in the storage rack.
Receptacles can be plastic 5 gallon pails, plastic garbage cans, wood troughs lined with plastic sheeting, etc. I use an all-plastic toilet brush, rubber gloves, and an old pair of channel locks to clean and handle the material. A little dilute acid on your skin will prickle but is not immediately hazardous if washed off. Wear a rubber apron if you need to splash.
Dispose of spent pickle by neutralizing it with Arm and Hammer laundry detergent until it no longer foams. Then strain out the silt. The pickle residue contains common salt, some iron chloride, and unreacted sodium carbonate plus the detergent's active ingredients. Most places you can run this down the drain. Weak acids you cannot.
Perform all acid pickling out of doors in open air and away from parked cars. The fumes of muratic acid drift forever and form inerradicable rust patches wherever it can find bare metal. Do not store acid indoors expecially in the shop. Set up a small shed of cabinet for them and high volitility solvents and gas cans in a downwind spot on your property. Lock it against prying fingers.
A light acid pickle followed by a bead blast is quick and effective - far more so than either alone.
I prefer muratic acid for pickling because its readily available at the boc store and its end products are sewer friendly. Surfuric acid isn't readily available by retail in my market so I tend to discourage it beside the neutralized sulfate ions are not real swer friendly. Muratic acid fumes can be a problem but, again, work out of doors in free air.
Last edited by Forrest Addy; 07-24-2007 at 12:41 AM.