Why no stainless steel tank

[eelnoraa]

So why? too expansive?

 

[JKPAO]

The $$$$$ and technology!
See you topside! John

 

[Rainer]

Chobham, RH armor, Depleted Uranium Strike Plates, Kevlar mesh all make for a stronger tank than SS.

 

[emoreira]

Ok, but all those materials mentioned used in battle tanks and weapons would make a dive tank incredible expensive.
Stainless steel would make a dive tank more expensive than an Alu tank or Steel tank, but would have a longer life.

 

[Rainer]

Wait, who said anything about dive "tanks"?

 

[Akimbo]

There are some stainless steel pressure cylinders available for high corrosive materials and high purity applications. My understanding is 300 series stainless doesn’t have great cyclic fatigue resistance so they fail hydros more often.

Considering several of us on Scubaboard have steel cylinders born in the 1950s, it is hard to justify much cost increase based on longevity. I did investigate having some Titanium (I forget the grade) 6000 PSI cylinders made for bail out systems back in the 1970s. I understood that most grades of Titanium have excellent cyclic fatigue characteristics. It is strong and light enough that you could design for 10,000 PSI and still have buoyant bottles.

 

[elan]

Ok, but all those materials mentioned used in battle tanks and weapons would make a dive tank incredible expensive.
Stainless steel would make a dive tank more expensive than an Alu tank or Steel tank, but would have a longer life.

Why would you care extending their life. I currently have lp 72 tanks older than I am and they will likely overlast me. If you divide the pricz of the tank by the number of dives made overtime it will likely be well below the cost of the fills.

 

[duckbill]

I'm not so sure stainless would necessarily have a "longer life". The stainless with which I have worked was pretty susceptible to work hardening and embrittlement.

 

[elmer fudd]

There are some stainless steel pressure cylinders available for high corrosive materials and high purity applications. My understanding is 300 series stainless doesn’t have great cyclic fatigue resistance so they fail hydros more often.

Considering several of us on Scubaboard have steel cylinders born in the 1950s, it is hard to justify much cost increase based on longevity. I did investigate having some Titanium (I forget the grade) 6000 PSI cylinders made for bail out systems back in the 1970s. I understood that most grades of Titanium have excellent cyclic fatigue characteristics. It is strong and light enough that you could design for 10,000 PSI and still have buoyant bottles.

I've read that modern carbon fiber bottles are actually capable of handling much, much higher pressures than they are rated for. Pretty impressive, considering some of them are already rated to 5000 psi.

 

[ajduplessis]

I did not find that steel cylinder is that much more expensive that the ali cylinders, but then again we have to import everything. I also like the characteristics of the steel; I don’t like system that change as the pressure drops.