That's what I would do, taking it back for a trade. Messing with those tanks can be pretty haserdous.

gillis

Absolutely do NOT mess with that stuck valve! Acetylene tanks are just large bombs waiting for a hapless sucker to set them off. Take it to a gas supply and let them deal with it. The last thing you need is for that valve to break while you're fighting with it and spew acetylene all over - for the two seconds it takes before it spontaneously decomposes and take you and your shop with it into the afterlife.

Gillis and Rich are absolutely right-DO NOT fool with this. Get it out of your shop and take it to someone who is trained to deal with these. Also, unless you need the heat of acetylene, you may consider propane or the MAPP replacement (usually propylene). I shifted over to MAPP (and then to propane) and am very happy I did.
Rob

Thanks so much for all of your comments, I am familiar with Acetylene and I love my torch, so no changing to MAPP gas for me : ) I am taking it to a welding shop tomorrow so they can have a go at it. Its been sitting in a friends kitchen for a year or so. He never got around to using it after he starting only doing lapidary stuff, apparently he tightened it a little too much. I just didn't know if there were any tricks out there... and yes I tried to turn it both ways, just in case, and no go either direction. I don't want to strip the pin, so the guys in the shop tomorrow will just have a good laugh at my expense..... oh well!

Your friend is a very strong person if he got it so tight. I'm voting for a defective valve. So even if the guys in the shop gets to open it, I would still ask for an exchange.

gillis

It doesn't do any good to have a new tank. The first time you take it in for a refill, they will give you an old rusty one that has probably rattled around in the back of a pick up truck for a while. I'm finding that I need to gently wack the little metal key with a leather mallet. Other people close it tighter than I do. If you do this, you must know the direction it should turn and use just enough force to get it started. Guys seem to be the ones who do this. (sorry guys.) When in doubt, take it to a welding supply store and let them make the decision of what and how to do it.

marilyn

thanks again everyone! they said it was a defective washer in the valve, and replaced the tank for me. very helpful and nice! my new one works great (not too rusty either) i'm back in business!