Blue-Collar Decisions Require Graduate-Level Brains

I’m trying to get my hands on some gas containers for my new acetylene rig.

Propane is no problem. You go to the hardware store and buy a tank. Acetylene is way trickier.

Acetylene can’t be extracted from a bottle at just any old rate. The rule of thumb is that you can only remove 1/7 of the total acetylene from the tank per hour. In very hot places, you can use more than that. Depending on what you plan to do with your gas, a small tank may make your work impossible. Some tasks require a lot of acetylene.

I want to do two things with acetylene: flame-straightening and welding. Propane will be for cutting and general heating. I may want to heat things so I can bend them.

Heat-bending and flame-straightening are two different things, although my guess is that most welders don’t know it.

If I want to bend a wrench to make a special tool, I will heat the entire area of the new bend until it’s red-hot. Pretty simple. This is not flame-straightening, and it takes a lot of gas.

If I have a shaft with a bend in it, and I want to straighten it, I will heat a very small area on the outside of the bend. When the metal cools, all or some of the bend will be gone. This is flame-straightening. It takes very little gas. It doesn’t work well if you heat a big area. It depends on creating a small hot area confined between cold areas.

Some people seem determined to believe it’s the same thing as heat-bending.

I’m thinking I’ll get a 125 cu. ft. oxygen tank, because it’s the biggest tank I can move easily. I’m pretty sure I want a 75 cu. ft. acetylene tank. I think it’s on the large side for what I want to do, and when it comes to tools, you should usually go big when you’re in doubt.

If I get a bottle of acetylene, brand new, it will run me something like $350. That seems like a very bad idea. Oxygen is in the same general ballpark.

The nice thing about welding bottles is that people are always trying to get rid of them online. Very often, you can get perfectly good bottles, sometimes full, for 20% of the new cost.

The big problem with buying used bottles is that they may be stolen. If they are, your gas supplier will know it. They won’t refill or swap them for you. They may confiscate them. This is bad.

People commonly rent bottles. I believe this is a very stupid idea. You save money up front, I would guess, but then you’re shackled to one supplier for as long as you own the bottle. There are a lot of jerks in the business, so that can be a problem. Also, do you really want to load up all your bottles and take them back in if you move? You would lose all that valuable gas.

All my bottles belong to me. I want to keep it that way.

Rental bottles, and any bottles that belong to companies that want to keep track of them, are generally stamped or embossed on their necks. They’ll say something like “Airgas” on them. I don’t know if every bottle that isn’t stamped is free for the taking, but it appears to be the case.

In areas where stealing bottles is a big problem, many suppliers will flat-out refuse to sell you a big bottle. I don’t know what the rationale is. I don’t see how owning your bottle makes you more likely to steal. Seems to me it would make you less likely, since, hello, you own it. But that’s how it is. There must be some rationale. If you want a bottle big enough to be useful, and you live in one of these areas, you have to rent. You may also be unable to get your own big bottles filled, even if you already had them when you moved to the area. Some suppliers are such jerks they won’t fill any bottles that don’t belong to them.

The kink in the owner-bottle strategy is this: bottles don’t last forever. They have to be certified every 10 years. This costs something like $30 per bottle. If you own an old bottle, this can work out well for you. You can take an old bottle in and swap it for a full bottle with a later date. This buys you time. I, on the other hand, started out with a new, empty bottle, and my supplier swapped it for a bottle which was not new. So I lost time.

Apparently, you need to check your dates and try not to let your bottles stick around too long. If you empty one, you need to swap it ASAP.

I don’t know if gas suppliers let you ask for bottles with recent dates. They should, because some people don’t go through gas fast, and if they had to take bottles that were about to expire, they would end up paying twice as much for gas. You might pay $35 for C25 and $30 for an inspection. And your bottle might fail, so you would have to buy another one.

The odds that a bottle will die while you have it are slim, because they commonly last 70 years or more, but it’s possible.

I don’t know how old my bottles are, but I’m going to check today.

I would rather have the freedom of ownership and risk paying for inspections than have someone else’s property here for months or years.

I found some bottles online, and I flat-out asked the sellers if they were stolen. I’m not going to buy stolen goods if I can avoid it.

When you get into something like this, it’s always hard to tell whether you have the right information. I researched as well as I could, so now I’m going to act on what I think I know.