possibly off topic project question, but involves welding none the less

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I am going to be welding up a wood furnace for my house. The metal tank I have for my firebox was free so I would rather not abandon it if I don't have to. The only problem is that it is coated with galvanizing and there will be air forced over it and into the house for heat transfer. I have not been able to find a good quick method for removing the stuff, and it looks like it would take forever to grind it off. And at the same time I believe the firebox will get hot enough that even if the galvanize isn't burning off, it will probably powder and get blown into the house that way. Does anybody have any suggestions? At what temperature will the coating start to be affected? I do not want to take any chances with a health hazard, so I will grind it all off if that is the only option. Thanks for your help.
Reply:One other thought, has anybody tried sandblasting to remove galvanizing?
Reply:your project might be to big use this technique. Soaking galvanized parts in vinegar is a safe and cheap way to remove it. Maybe old towels soaked in vinegar might work.
Reply:i'm not sure of the exact temperature that the zinc melts, but when i was burning it off of a practice piece last night, it turns to a liquid form before the base metal (cabon steel for me) turns red, or even starts to glow. it melted similarly to solder for me. you could use a furnace / old grill to melt pre-heat the metal (dependant upon size) and torch the rest of it... that would at least save you some propane and time. if it were me, i would get a low-grit (roughest possible) flap disk with a slight taper angle on it. this woudl work great for a large flat piece. even with a 4.5" grinder, you could sufficently remove the galv off of a 12x12 area in about 5 minutes i would think. i woudl opt for the grinding, just to be posistive that i got it all. no matter how much you heat it, the galv will still have a slight coating on the base metal, merely thinner. you'll know when it melts becuase it will turn VERY shiney... similar to chrome or molten solder. once it's heated and you melt off as much as you can (or scrape off the molten stuff), then grind it... that'll save some elbow grease. either way, i woudl reccomed grinding to make sure ALL of it is off since you are worried about health hazards.hope that helps.Later,Andy
Reply:Originally Posted by rsilveryour project might be to big use this technique. Soaking galvanized parts in vinegar is a safe and cheap way to remove it. Maybe old towels soaked in vinegar might work.
Reply:Build a really hot fire in it outdoors and let the zinc pollute your neighbors.WeldingWeb forum--now more sophomoric banter than anything else!
Reply:melting point of zinc = 787 F (420 C)boiling point of zinc = 1665 F (907 C)Zinc is dissolved by most common acids.  Regular vinegar will work.  Stronger acids, like hydrochloric acid, will work faster.Safety note:  Strong acids can be dangerous.If you don't KNOW what you are doing, don't do it.  If you can't, won't, or don't know to use proper safety procedures, don't do it.Further safety note:  The action of an acid upon zinc will release hydrogen gas.  Strong acids reacting with zinc will release the hydrogen gas rapidly.  Hydrogen is flammable!  Very-very-very-very flammable!
Reply:Originally Posted by MoonRiseFurther safety note:  The action of an acid upon zinc will release hydrogen gas.  Strong acids reacting with zinc will release the hydrogen gas rapidly.  Hydrogen is flammable!  Very-very-very-very flammable!
Reply:Originally Posted by MoonRise Hydrogen is flammable!  Very-very-very-very flammable!
Reply:My $0.02;Take it to a shop that has a sand blaster and pay them to clean the galvanization off for you.  Zinc fume poisoning isn't worth the risk.  You might also look in the phone directory for a local plating company.  They would have the right acid solutions on hand, in appropriate dipping tanks, to strip the zinc off for you quickly and easily.  This would save you the hassle of neutralizing and disposing of many gallons of contaminated acid solution once the stripping is done.Rsilver, soaking towels in vinegar is a creative solution.  However, I don't think you'd bring enough acid in contact with the zinc coating to remove much material.
Reply:Originally Posted by Rick MoranAs in the LZ-129 Hindenburg flamable!
Reply:After cutting and welding on galvanized quite a few times, I wouldn't build a stove out of it.  That stuff is NASTY.  I would build or find a better fire box.  Ya might not agree with me, but have you ever had the white fume fever?.....I have.  I grind it off before welding, but I can still smell it.  A wood stove can get red hot.  Enough to burn off any galv that was missed no matter how you take it off.  No Thank You, not in my house.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:I usually use muratic acid to remove galvanizing.  In a 30 gallon drum I use about a cup.  This summer, I did use a forge to burns some the coating off some old fittings. Any residue left will be powder and can be brushed away.  Dipping involves less labor.  There are a couple of threads in this forum about a guy who died from burning galvanizing off in a fire.  Do a search.  I posted one, though somebody had posted in prior to mine.  Ventalition is important whether burning or dipping in acid.
Reply:The soaking in vinegar took about two days for galvanized pipe elbows. The process is slow but relatively safe as long as you have good ventilation.