Stainless steel tanks

[blacknet]

Hello,

can anyone tell me the company who makes the DOT approved ss tanks for use in the US?

thanks,

Ed

 

[luvdiving]

Hi blacknet

I've never heard of such an animal. If it is made, it must be some big $$$.

 

[blacknet]

Hello,

Well to my knowledge they do have some $ tag associated with them, but I don't have any figures, yet. Was told that there's someone on this board who has a set. Trying to find out more info about them

Ed

 

[rcontrera]

The stainless steel tanks made for the diving industry were being made in the late 70s and early 80s. It was a small manufacturing firm in the heartland (I want to say Kansas, but am suffering a senior moment right now) that was making small stainless cylinders for the medical and scientific field.

When they made the announcement that they were coming to the diving market, they were going to be selling in the $200 to $300 range. At that time, you could buy a "steel 72" for about $75 and an aluminum 72 or 80 for about $90 so stainless was going to be big bucks! However, the steel workers union came in and got all the workers to sign up. They then made some pretty hefty demands and the company closed it's doors.

I also know of a guy that was having Titanium cylinders brought in from the former USSR. I saw one that was approximately 80 cubic feet of air and was about the size of a football! Real cool!! However, DOT and cost considerations have shifted those to very specialized markets.

Just my $.02

Ray

 

[Phillip]

I have heard that there used to be a company that made stainless steel scuba tanks. Does anyone know what the name of it was. Also, why aren't stainless tanks used today? Thanks, Phillip

 

[JoeH]

I wonder if it is the expence?
Good question!

 

[100days-a-year]

As a young lad I worked in an oilfield machine shop and asked why SS wasn't used everywhere corrosives or moisture were a problem .I was told the SS is expensive,hard to work and less ductile the other steels making it more likely to fail if used in an application where it was bent,stretched or strained repeatedly.Steel and alumimum are more durable and cheaper it seems.

 

[Pez de Diablo]

100days-a-year once bubbled...
As a young lad I worked in an oilfield machine shop and asked why SS wasn't used everywhere corrosives or moisture were a problem .I was told the SS is expensive,hard to work and less ductile the other steels making it more likely to fail if used in an application where it was bent,stretched or strained repeatedly.Steel and alumimum are more durable and cheaper it seems.

I work in the oil and gas industry for an engineering company that specializes in corrosion science and have also worked for a manufacturer. I think the fact that it is less ductile (prone to stress fractures) and more expensive would be reason enough to avoid the use of SS. Scuba tanks are engineered for the task at hand with a huge safety factor in the design. A benefit of using stainless would be to combat corrosion and I don't think corrosion is a problem with scuba cylinders. I would be interested to know if corrosion has ever been the cause of a failure.

 

[FredT]

There was an outfit in West Palm Beach trying to get DOT approval for a SST tank rated at 4500psi. Due to the work hardening performance of SST under pressure it could not be effectivly hydroed. lathough the tank was sound it would give garbage numbers in a hydrotest. Recertification was to be by visual and ultrasonic inspection.

Since DOT specs are written around hydros they wouldn't ever approve the tanks, so the company went tit$ up. I went over the numbers with the guys and the tanks were sound. The failure was with the DOT regulator's myopia.

This isn't the only case where the public has been screwd out of a good product or paid WAY too much for a service thanks to incompetance or pissing contests between agencies by the folks in the government who are there to "help" us!

FT

 

[Pez de Diablo]

Fred T,

How were the tanks priced?
I wonder what the disadvantages are for using a 4500psi tank? I think typical first stages are rated for 4500 psi - so it wouldn't effect currently manufactured regs/first stages.

Yes bureaucracy can get in the way. I do know that for Canadian standards (CSA) each area has a committee made up of industry experts that write/review the specs proposed or modifications to the specs. It is then the governments role to adopt the recommendations of the applicable committee.