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hyperbaric chamber
- Thread starter Jeff Allen
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Great for treating Altitude ( Mountain) Sickness. No relevance for divers.
I can't testify to it since I haven't seen the certification calcs, but adding those vertical members would be pretty expensive shelving or decoration.
Seriously, I would think that @Dr Simon Mitchell would have first hand experience with that system. I'm not even sure what certification agency New Zealand uses.
Bob DBF
Contributor
To find an answer.
It's an interesting question, as the answers have shown.
It's the first post by someone who, by the profile, is not certified. He could have put it in DIY 'cause that's where people that make things would be, and might have the expertise to answer. And it worked.
Bob
Unfortunately we had to use one of those on Kiliminjaro for a climber with AMS. It is a remarkably effective device.
The cost of labor alone makes square chambers less than ideal. Ignoring the stress risers of the corners, and potential failure points for each weld, each weld adds significant cost to any pressure vessel, not just hyperbaric chambers.
When I'm at home I do little fab jobs for ranchers and farmers in my area. I quote welding jobs based on $1 US per tack, and $1 US per inch, plus a minimum to come out. An 8 foot x 8 foot box is 96 inches per seam, x 12 seams. Even ignoring tacks and the fact that it will almost certainly require a multi-pass weld, you can quickly see the cost of the monkey with the gun isn't cheap comparatively to a circular pressure vessel. Pressure likes to make square things round. So in order to even make something functional, you need to increase your wall thickness, you would need to add structural reinforcement, plus all of the extra time, prep, and weld to accommodate that.
Now, because it's a pressure vessel, it needs to be done by someone who has the certification to actually do those welds. There's no such thing as a "certified welder," where you can do anything you want. You get certified per process, material thickness, material composition. Someone who can weld 6G pipe for all thicknesses FCAW-G may not hold any other certifications. He's not going to be able to weld 1" stick plate for structural just because 6G pipe. So, you've gotta get someone who actually holds a certification for what you want done. All of those joints also have to be inspected by a CWI or someone else that's been designated to certify them. X-raying welds on something the size of a chamber isn't easy or cheap. Add 10 more welds because it's a box and your costs skyrocket.
None of that is including anything else, hatches, viewports, penetrations through the structure. Just the labor alone to build the thing is probably not worth it, even if you take away all other considerations.
I have the knowledge and skill to DIY one. I even have the tools to build one, albeit I don't have the testing capability. I would never even remotely consider it. Even if I were to source all of the material, consumables, parts, etc. at cost, I still couldn't build one cheaper than buying one.
When I'm at home I do little fab jobs for ranchers and farmers in my area. I quote welding jobs based on $1 US per tack, and $1 US per inch, plus a minimum to come out. An 8 foot x 8 foot box is 96 inches per seam, x 12 seams. Even ignoring tacks and the fact that it will almost certainly require a multi-pass weld, you can quickly see the cost of the monkey with the gun isn't cheap comparatively to a circular pressure vessel. Pressure likes to make square things round. So in order to even make something functional, you need to increase your wall thickness, you would need to add structural reinforcement, plus all of the extra time, prep, and weld to accommodate that.
Now, because it's a pressure vessel, it needs to be done by someone who has the certification to actually do those welds. There's no such thing as a "certified welder," where you can do anything you want. You get certified per process, material thickness, material composition. Someone who can weld 6G pipe for all thicknesses FCAW-G may not hold any other certifications. He's not going to be able to weld 1" stick plate for structural just because 6G pipe. So, you've gotta get someone who actually holds a certification for what you want done. All of those joints also have to be inspected by a CWI or someone else that's been designated to certify them. X-raying welds on something the size of a chamber isn't easy or cheap. Add 10 more welds because it's a box and your costs skyrocket.
None of that is including anything else, hatches, viewports, penetrations through the structure. Just the labor alone to build the thing is probably not worth it, even if you take away all other considerations.
I have the knowledge and skill to DIY one. I even have the tools to build one, albeit I don't have the testing capability. I would never even remotely consider it. Even if I were to source all of the material, consumables, parts, etc. at cost, I still couldn't build one cheaper than buying one.
Just to expand on your point, this post might be interesting of other divers: What is Saturation Diving?, Post #32
Super interesting! I never knew who was in charge of all of the non-land based structural stuff. When I was welding quite a bit, I got tested for any thickness plate and any thickness 6G pipe, AWS D1.1, with stick and dual shield flux core, plus both with a tig root pass. It was expensive as hell ($500 per process x 4 sticks out in my head). None of that would qualify me to weld anything that went on or in the water, and wouldn't qualify me for stainless anything.
It's really amazing just how specific some of this stuff really is. I knew a guy that did nuclear pipe, 6G, stick with tig root. All he ever did was work in nuclear plants for probably 10 years, plus another 10 years of general fab shop welding, then went to an airline. Had to get a bunch of new tig certs to weld turbine vanes with all sorts of funky super alloys, lots of inconel, hastelloy, etc. The company was paying for his tests, and paid for his job interview test, but I can tell you he didn't have a single good night of sleep before having to cert on any of them. And that's after 20 years of being a full-time welder. He said he tallied up the "cost" of all of the certifications he had to do over the years and it rivaled the cost of an average university tuition.
A company like Ingalls Shipbuilding pays beaucoup dollars a year to keep their welders current. I don't know what their specific requirements are, but AWS D1.1 (structural steel) calls for a full re-cert every 6 months unless you can prove that you're welding your certified process regularly. I'd imagine ASME has a similar requirement.
Nice history lesson. Not many people know that the ASME came about because steam boilers started blowing up on a regular basis, back in the days where men were men and most women were more manly than any millenial today.
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