In the Workshop, Ep. 4: How to correctly open welding gas bottles

Simple advice in the fab shop often gets overlooked, but this is much too important to skip over. Opening gas bottles require special attention to detail. In this newest episode of In The Workshop, I'll walk welders through the proper and safe way to open gas valves. There is one rule and one exception, especially for especially acetylene cylinders.

Video Transcript

"Hi, I’m Josh Welton, and in this edition of In the Workshop, I’m going to tell you a little bit about opening bottles, which you might think is kind of easy, and it is. But there’s one thing that a lot of people don’t know, and I run into it all the time. I always assume that people know this, and it’s not something that seems to be as common knowledge as I think it should be, so we’re going to hit it here.

"It’s basically talking about the valves on gas bottles. On most bottles of inert gas or oxygen, you’re going to have a style where it seats when it’s all the way closed and when it’s all the way open. So when you open it all the way up, it actually seals at the top; and when you close it all the way down, there’s a seat and it seals at the bottom. So, you don’t want to open this like a quarter turn or a couple of times. You want to go all the way open or all the way closed. If you don’t do that, then you run the risk of getting contamination, of getting air in the line, and a much greater chance of the bottle leaking down.

"There’s only one exception, and it’s acetylene. Acetylene is pretty much going to be the most dangerous thing you have in your shop. If you use it above 15 PSI, it violently decomposes, which means it basically turns into a potential bomb, so you want to be very careful with it.

"This [acetylene] bottle is designed where internally it has a porous material that the acetylene is kind of in the acetone. You have acetone and it’s impregnated into the porous material. These bottles need to be upright. If you travel with it flat, just make sure you put it upright a while before you use it to get everything to settle. With an inert gas bottle, you’ve just got a heavy steel bottle and then the gas is inside of it. On this [acetylene bottle], there’s a lot more going on. There’s that porous substance, there’s the acetone, and then there’s acetylene. And what happens is, when you open up the valve, the change in air pressure is what allows the acetylene to come out.

"This bottle, because of the difference in design and the potential calamity that could be caused by acetylene, is designed differently. There is no seat at the top. You’ve got it sealed all the way closed. And then when you open it, you only open this bottle a quarter of a turn. And that’s so that if something goes wrong, you can quickly come over and turn it off within a couple of seconds. One hand movement and you’ve got it turned off. If you’ve got it opened up all the way, you can’t do that.

"So that’s the one super important caveat. All the other gases, whether you’re talking about a 75/25, 100% argon, helium, a 90/10 mix—they all have that valve that’s designed so it seals all the way open and it seals all the way closed. Acetylene is the one that doesn’t, and this one you’ll want to open only a quarter of a turn, and it’s for safety reasons.

"So, that’s pretty much it. It’s a simple kind of thing to know, but I’ve told so many people this and they don’t believe me. I have to look up the reference material and show them. “No, it’s right here. I’m not lying.”

"So, something to think about. Again, quarter turn with acetylene. Everything else is all the way on or all the way off."

Stay tuned for more of my In the Workshop videos from my Detroit welding shop. I'll continue to offer up all kinds of helpful advice for welders. Whether it’s offering simple advice, leading one-on-one workshops, helping college classes, or having a family member throw on a helmet and lay some beads, I love teaching and seeing the light bulbs go on.

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