Cave Fills on LP tanks

[rjack321]

For DOT specification tanks (includes 3AA & 3AL) -- "A cylinder must be condemned...when permanent expansion exceeds 10 percent of total expansion."

The tank does not need to return to its original size in order to be requalified. Most tanks do have an almost imperceptible permanent expansion. I have never heard of the 'two month' relaxation theory either.

I had a 3AL2015 (that's an aluminum medical O2 bottle) come back from hydro with 22% permanent expansion once. It had never been overfilled but needless to say it was a fail lol I was a little shocked I couldn't see the bulge.

3AA2400+ steels filled to 3600psi might fail "sooner" than those only filled to 2640psi. Its still likely to be longer than anyone is actually diving and they are far more likely to fail visual due to interior rust pits than they are to fail hydro. 3AA steels are so insanely overbuilt that I have seen some O2 supply bottles from my gas supplier dating from before WW2. They far predate USDOT (they have ICC numbers). So if a non-overfilled 3AA can last 80+ years in service so what if an overfilled 3AA "only" lasts 40yrs.

 

[BRT]

I had a 3AL2015 (that's an aluminum medical O2 bottle) come back from hydro with 22% permanent expansion once. It had never been overfilled but needless to say it was a fail lol I was a little shocked I couldn't see the bulge.

3AA2400+ steels filled to 3600psi might fail "sooner" than those only filled to 2640psi. Its still likely to be longer than anyone is actually diving and they are far more likely to fail visual due to interior rust pits than they are to fail hydro. 3AA steels are so insanely overbuilt that I have seen some O2 supply bottles from my gas supplier dating from before WW2. They far predate USDOT (they have ICC numbers). So if a non-overfilled 3AA can last 80+ years in service so what if an overfilled 3AA "only" lasts 40yrs.

I have seen them from the WW1 era. A friend of mine owned one. It failed hydro for rust, not for expansion.

 

[jerrwhy01]

Quick update. My carport was still in tact this morning.

Whew!

 

[Scuba_Aaron]

I overfill my LP50's and 85's to 3000 regularly with my own compressor, damn the torpedoes, full steam ahead!!!!!

 

[Superlyte27]

I overfill my LP50's and 85's to 3000 regularly with my own compressor, damn the torpedoes, full steam ahead!!!!!

That's weak

 

[Scuba_Aaron]

Weak? care to explain?

 

[lv2dive]

LP tanks are routinely filled to 3600-4000 in cave country. I imagine that was what SL was referencing.

Weak? care to explain?

 

[Superlyte27]

Thanks Kate. Exactly.

 

[JBFG]

4000 psi on a LP?!? The garage is definitely exploding tonight.

 

[Storker]

It's only 150% of service pressure, i.e. the same as hydro test pressure here on the right side of the pond...