PST LP 95 Failed first hydro-Rare?

[Hoosier]

3500 to 3600 is what i usually get

I mean, even in mid-west........ In FL... I am sure you will get that much.

 

[fireboat]

Thanks for info everyone. I had this tank VI right after I got it and figured everything was good. After all, I have a 35-yo steel 72 that I still use.
I learned a lesson and most likely will go new on the next tank so that I know how it is treated and maintained. It is buyer beware when it comes to used tanks.
Evidently, over pressurizing can fatigue the tank, especially if filled improperly.

 

[PerroneFord]

Evidently, over pressurizing can fatigue the tank, especially if filled improperly.

Filling a tank to its RATED pressure can ruin it too.. if it's done hot. My fills on my double 80s take about 20 minutes. So figure 10 minutes to fill a single. How many of you wait 10 minutes for a full fill?

 

[jpcpat]

I'm missing something Important here.

My LP Faber is rated to 2,640PSI in the US and 3,900 in the EU. Will an overfill to 3500 really fatigue the metal THAT much?

Also, the hottest fill I ever saw didn't exceed 150 degrees. Is steel THAT sensitive to heat. If we were talking 300+ I would understand.

PLS Note: I'm not trolling, I really do want to understand.

 

[PerroneFord]

I'm missing something Important here.

My LP Faber is rated to 2,640PSI in the US and 3,900 in the EU. Will an overfill to 3500 really fatigue the metal THAT much?

Also, the hottest fill I ever saw didn't exceed 150 degrees. Is steel THAT sensitive to heat. If we were talking 300+ I would understand.

PLS Note: I'm not trolling, I really do want to understand.

No the steel is not that sensitive to overpressure. Which is why I mentioned the tank I used a few weeks ago with a 1974 original hydro.

However, the tolerances on a steel tank are pretty tight. And for Hydro purposes the tanks are filled in less than 10 seconds. to almost twice working pressure. It's a pretty strenuous test.

 

[Hoosier]

I'm missing something Important here.

My LP Faber is rated to 2,640PSI in the US and 3,900 in the EU. Will an overfill to 3500 really fatigue the metal THAT much?

Also, the hottest fill I ever saw didn't exceed 150 degrees. Is steel THAT sensitive to heat. If we were talking 300+ I would understand.

PLS Note: I'm not trolling, I really do want to understand.

As I know, the tensile on the tank is different between US and EU tanks. So, EU tank can hold higher pressure than US one.

 

[wreckchick]

It takes much longer than 10 seconds to pressurize a tank for hydro. Probably more like 3-5 minutes. Remember also that it's in water and filled with water. I've never pulled a hot tank out of the hydro jacket.

Also, PFord, the "time" a fill takes isn't as important as the rate of flow. 400-600 psi/minute is a general rule I follow for air. It shouldn't take you twice as long to fill your doubles as it would singles unless you're filling directly off the compressor and have it wide open.

My bet on these tanks is that they were hydro'd improperly without the 90% test done prior to the actual hydro. I've never seen a 5 yr old steel fail for any reason when tested properly.

Rachel

 

[PhilEllis]

Filling a tank to its RATED pressure can ruin it too.. if it's done hot. My fills on my double 80s take about 20 minutes. So figure 10 minutes to fill a single. How many of you wait 10 minutes for a full fill?

A quick look at the properties of the steel alloys used in modern scuba cylinders would seem to indicate that the temperatures reached in a filling operation, even an extremely rapid one, fall FAR short of the temperatures necessary to even BEGIN to affect the mocular structure of the metal. The bottom line is......some cylinders fail hydro and others don't. I don't think there is anything a user or fill operation can do, except sticking closely to the specified fill pressure, that will effect the ability of a particular cylinder to pass the hydro test. Anyway, just my thoughts.

Phil Ellis

 

[SparticleBrane]

HI Guys, My 5 year old PST LP 95 just failed it's first hydro at my LDS. It wasn't from rust, they said it failed to return to specs after testing.

From what I understand about hydrostatic testing, the tanks never actually return "to spec"--the metal is in fact permanently stretched and that's how they determine whether or not it passed. The difference between the starting water level in the jacket and the ending water level has to be within a small range--if the tank has expanded too much during the test then the tank fails. If your hydrostatic test operator expects all the tanks to return "to spec" then I wonder how many tanks they fail on a regular basis...

 

[ChrisA]

I'm missing something Important here.

My LP Faber is rated to 2,640PSI in the US and 3,900 in the EU. Will an overfill to 3500 really fatigue the metal THAT much?

You sure it is the SAME tank? Faber makes tanks that look just like LP tanks that are really HP tanks. The only way to know is to read the fill pressure stampped on the tank. I dounbt thse EU tanlks are the same as what we see here.

Anyone is Europe ever seen a tank stamped "3AA2400"? I doubt it.

How are hydro tests done in the EU? Could the same tank pass in Europe and fail in the US?