How old is "too" old for aluminum cylinders?

[Wallowa]

Many of those that have been personally present when a cylinder failed due to sustained load cracking are dead.

Good one Scared Silly! That explains a lot....stick with steel...

 

[Still Kicking]

"erroneous readings'....that says a lot, that false positives are possible...goofy. Has anyone actually verified a tank failing under pressure due to sustained load cracking? How did it fail? Not second hand but personal observation. Sorry, it seems like the sky is falling. One of my responsibilities was to VIP and inspect 50 cylinders we had in our program; steel and aluminum, never had one fail a hydro or did I ever see a crack...that spans 25 years...so yes I am skeptical of the fearfulness seen today and the forecast of doom....I go with the above quote: "If is passes hydro and visual" it is good to go....but hey, I could be wrong....

Yes, Walter Kidde 80 failed in hydro after passing eddy current test. Big bang ...lots of water. Could have have easily killed someone had it been a fill.

 

[Wallowa]

Yes, Walter Kidde 80 failed in hydro after passing eddy current test. Big bang ...lots of water. Could have have easily killed someone had it been a fill.

Does that not beg two questions? Why did it fail? And if a crack in neck failed then eddy testing is useless. "big bang"? I thought bottles were filled with water and at most a very small air pocket? Honestly have never been party to a hydro catastrophic failure, only bottles I knew of that failed during hydro did so when they did not recover their original internal volume within 10% after hydro pressure [5/3] was released. Been years hope those numbers are accurate....only bottles that I remember failing by splitting open during a fill did so because back in the '80s when painted and baked to set paint it ruined the strength of the tanks....another issue entirely.

 

[Still Kicking]

C

Does that not beg two questions? Why did it fail? And if a crack in neck failed then eddy testing is useless. "big bang"? I thought bottles were filled with water and at most a very small air pocket? Honestly have never been party to a hydro catastrophic failure, only bottles I knew of that failed during hydro did so when they did not recover their original internal volume within 10% after hydro pressure [5/3] was released. Been years hope those numbers are accurate....only bottles that I remember failing by splitting open during a fill did so because back in the '80s when painted and baked to set paint it ruined the strength of the tanks....another issue entirely.

Failed due to sustained load cracking, missed by the eddy test. Bang because pressure wave from the crack reptured the burst disc on the hydro pot.
Most tanks that fail, fail due to excessive permanent expansion. This is different.

As for the pre 1990 policy, try explaining to a customer why one pre '90 tank can be filled and another can't. Try explaining to a customer who wants to buy used tanks which <1990 tanks they should buy and which ones they should pass on.

 

[Wallowa]

Good instructional video of hydro process...note no air in tank during hydro...and must not have a permanent expansion more than 10%..

 

[Tracy]

"erroneous readings'....that says a lot, that false positives are possible...goofy. Has anyone actually verified a tank failing under pressure due to sustained load cracking? How did it fail? Not second hand but personal observation. Sorry, it seems like the sky is falling. One of my responsibilities was to VIP and inspect 50 cylinders we had in our program; steel and aluminum, never had one fail a hydro or did I ever see a crack...that spans 25 years...so yes I am skeptical of the fearfulness seen today and the forecast of doom....I go with the above quote: "If is passes hydro and visual" it is good to go....but hey, I could be wrong....

Yes, more than one.
One failed leaking through the crown of the tank within months of hydro. That was the last 6351 tank I ever filled. Eddy test can't see into the crown, only the threaded area. It cracked on a fold inside the tank crown.
I have 5 AL cylinders with cracks that I use teaching the VIP course.

Out of all the tanks I have serviced over the years and I would guess that number to be well north of 1000. I have only had two fail hydro for reasons I can't figure out. One was an old steel 72 that was visibly perfect yet the steel was brittle as hell and failed miserably. The other was an aluminum nitrous oxide bottle that was visually perfect. I assume it had been cooked based on what it was used for, but no way to know for certain as it didn't have the tell tale torch marks. Every other fail was from obvious visual defects.

 

[Still Kicking]

Yes, more than one.
One failed leaking through the crown of the tank within months of hydro. That was the last 6351 tank I ever filled. Eddy test can't see into the crown, only the threaded area. It cracked on a fold inside the tank crown.
I have 5 AL cylinders with cracks that I use teaching the VIP course.

Out of all the tanks I have serviced over the years and I would guess that number to be well north of 1000. I have only had two fail hydro for reasons I can't figure out. One was an old steel 72 that was visibly perfect yet the steel was brittle as hell and failed miserably. The other was an aluminum nitrous oxide bottle that was visually perfect. I assume it had been cooked based on what it was used for, but no way to know for certain as it didn't have the tell tale torch marks. Every other fail was from obvious visual defects.

Out of all the tanks i tested, the most failures seem to be old 72s that seem to have been sitting unused for years (long expired previous hydro).

Most 72s pass no problem but some of those 72s expand like crazy. Never any visual defects i could see. Aluminum tanks hardly ever fail.

 

[Wallowa]

Out of all the tanks i tested, the most failures seem to be old 72s that seem to have been sitting unused for years (long expired previous hydro).

Most 72s pass no problem but some of those 72s expand like crazy. Never any visual defects i could see. Aluminum tanks hardly ever fail.

Interesting exchanges and information. I am not an expert and did not sleep in a Holiday Inn to qualify as one...as others I have vip'd and hydro'd many, many bottles....do have a question: If crack was within the "crown" why and how did it fail? Crown I am imaging is not a sealing surface as are the threads and of course o-ring/seats. Did it just start a slow leak or a rapid one? New one on me.

Old 72cf 2250 bottles? The steel 72cf I bought in 1955 just past it's 19 [hope I count correctly] hydro and yes bottle always kept full...only death knell for a steel bottle is to get water, particularly salt water, inside and not dry it out; then pump in high O2 and rust city. Or be really dumb and pump it way over rated pressure repeatedly.

Thanks again for everyone's input....I am always learning...

 

[Still Kicking]

.only death knoll for a steel bottle is to get water, particularly salt water, inside and not dry it out; then pump in high O2

The 72s that fail are dry and rust free, and have never seen more than 21 percent. A small minority of tanks overall for sure but there is no mistake when you test one - massive expansion and not much elasticity.

 

[Wallowa]

The 72s that fail are dry and rust free, and have never seen more than 21 percent. A small minority of tanks overall for sure but there is no mistake when you test one - massive expansion and not much elasticity.

Wow...do you happen to remember who made the steel bottles that had that huge expansion with little recovery? Oh, I meant "knell" not "knoll"...old fingers and older mind!