Where do I get a welding tank filled?

For the most part, they probably won't refill the one you have if you actually have one. Because they don't know if the one you have has been compromised so they will take your empty tank and sell you a new full one. It is too much of a safety risk to refill the one you have.

But on a side note, it is a little scary that you are coming online to ask where to get one filled. Perhaps you shouldn't be trying to mess with welding until you completely understand what is involved.

Most larger cities have welding supply stores that do that.

Gas suppliers also do it. (oxygen, helium, CO2 etc)

Check your yellow pages for welding supply.
Companies here that supply gas have names like:
Metro Welding
Toll Gas and Welding
Oxygen Supply Co

If nothing else, find a local welding shop and ask them where they go to get their tanks refilled.

there will be a company in your area that refills bottles. (assuming you are in America)

look under welding supplies. somebody will be covering your market...

most of the time, at least in my dealings, they will sign you into a lease, and take your bottle up front.

you pay for gas. in ten years, you sign a new lease, and then rent their bottle.

Cool! Thanks a lot for all the advice! Very helpful. I'll check the Yellow Pages and see how it goes.
Again thanks.

I appreciate the concern, but fear not I am cautious and reasonable. I've worked on many semi-adjacent fields: jewelry, stain-glass making (soldering), etc...

Like Rockhead says, you will normally lease the bottles, at least for oxygen and acetlyene. Frequently, you own your own bottles for inert gases is you get into that. The company that leases them to you exchanges full ones for the empties. Don't worry about Krumple. These bottles have serial numbers and are made and tested in accordance with ICC regulations. If you have a tank that is not, you are not going to get it refilled.

Now, if you are dealing with air tanks for scuba diving, it becomes more restrictive.

oxy bottles are an exchange.
here in aust I just take the empty bottle to our local hardware and pick up a full one.
the emptys are kept by the hardware store until they have a bunch (not sure how many) then sent to be refilled.

The refiling company do all the testing.

That is a stupid answer. he is researching now, that is why he is asking, god your a lot of help and by the way no one takes my tank when they refill them. only local hardware store like Lowes or Ace or Home depot switch out Propane tanks because they don't store a refilling tank or have a station. Gas is filled Oxygen is switched out.

No, he is not researching now.

The question was asked around five years ago.

In future, please pay more attention when you choose to be grumpy with someone.