Closed Faber Steel HP100

[Tracy]

hydros for most scuba tanks is 5/3 working pressure so for most aluminum tanks that’s 5000psi. LP Steels get 4000psi and HP steels ~5800psi depending on pressure.

A few hundred here or there then using the tank is more often than not. It’s the cave fills that sit for months at a time in a cave that will most often fail hydro.

And cave divers doing “hydro fills” on their tanks in which the stamped pressure on the tank is their turn pressure is highly unsafe. Ever notice how a lot of cave divers always have new tanks?

Not saying it doesn't exist, but I have never seen a scuba tank with a 5800 hydro pressure.
All of the high pressure steel tanks I have seen have a hydro test pressure of 5250. 5/3 is the test pressure for 3a series.
Exemption tanks have a preset test pressure as part of their special permit.
I have never seen tanks fail from sitting long periods of time with cave fills in them.
No, I haven't noticed cave divers with new tanks, unless they are new cave divers. What I have noticed is the hundreds of sets of rental tanks in cave country from the 70s, 80s and 90s that have been sitting at 3600 for 20+ years and still passing hydro every 5.
Unless you have some evidence to the contrary, which you don't, maybe stop passing regurgitated information?
The elastic limit on a 3aa2400 tanks usually falls between 4200 and 4800. Filling it to 3600 is not damaging the steel, it may be ill advised and even illegal, but it isn't going to harm the tank. It is getting closer to that line than one may deem a good idea, but it isn't actually hurting the tank.

 

[rob.mwpropane]

Not saying it doesn't exist, but I have never seen a scuba tank with a 5800 hydro pressure.
All of the high pressure steel tanks I have seen have a hydro test pressure of 5250. 5/3 is the test pressure for 3a series.
Exemption tanks have a preset test pressure as part of their special permit.
I have never seen tanks fail from sitting long periods of time with cave fills in them.
No, I haven't noticed cave divers with new tanks, unless they are new cave divers. What I have noticed is the hundreds of sets of rental tanks in cave country from the 70s, 80s and 90s that have been sitting at 3600 for 20+ years and still passing hydro every 5.
Unless you have some evidence to the contrary, which you don't, maybe stop passing regurgitated information?
The elastic limit on a 3aa2400 tanks usually falls between 4200 and 4800. Filling it to 3600 is not damaging the steel, it may be ill advised and even illegal, but it isn't going to harm the tank. It is getting closer to that line than one may deem a good idea, but it isn't actually hurting the tank.

When a manf goes through testing a tank (like for certification, not hydro), they have a choice of either X amount of cycles at burst pressure, or X amount of cycles at hydro pressure? I can't remember what it was, but they had to go through like 5000 cycles @ burst or 10,000 @ hydro... and then it still has to pass hydro after all that. All opt for the burst pressure because it's less cycles, which makes sense.

Tracy do you know? I know I read it online and here somewhere...

I'm not trying to pass along wrong information, I honestly can't remember what the testing process was, but I remember thinking I'll never come close to even touching those cycles with my scuba tanks / fills.. so me overfilling by 10% or 15% or whatever isn't going to do anything.

To each their own though,.... dive and let dive... my compressor, my rules

 

[Tracy]

When a manf goes through testing a tank (like for certification, not hydro), they have a choice of either X amount of cycles at burst pressure, or X amount of cycles at hydro pressure? I can't remember what it was, but they had to go through like 5000 cycles @ burst or 10,000 @ hydro... and then it still has to pass hydro after all that. All opt for the burst pressure because it's less cycles, which makes sense.

Tracy do you know? I know I read it online and here somewhere...

I'm not trying to pass along wrong information, I honestly can't remember what the testing process was, but I remember thinking I'll never come close to even touching those cycles with my scuba tanks / fills.. so me overfilling by 10% or 15% or whatever isn't going to do anything.

To each their own though,.... dive and let dive... my compressor, my rules

I do not know the manufacturer test requirements. Never tried to make my own.

I have tested tanks to failure out of sheer curiosity. Never to burst, just cycled at higher and higher pressures until they stopped coming back.
Steel tanks are very elastic, just like a rubber band, you can stretch it a certain amount and it will come back forever, but if you go too far, (beyond the elastic limit) it won't come back anymore. If you keep stretching it, it will break. Tanks are very similar. The hydro test is testing the elasticity of the metal, does it come back to where it started.
3600 on a 3aa2400 is still very much in the elastic range of the tank.

 

[Jona Silverstein]

I have never seen a scuba tank with a 5800 hydro pressure.

You are right. Its been a long few days and everything was a bit jumbled. 5250 is standard for HP tanks. Its our damn carbon cylinders that are like 6000 and 7500 respectively.

But we have seen PST Tanks fail before and the common denominator on them was that they were left full and overfilled. We dont need the extra gas so we dont overfill them anymore. We are a big advocator for buying the right size tanks and not trying to fit an elephant into a Horses body.

I will admit we do fill LP85s to about 3300hot because its super hot here in the summer and tanks rapidly cool when they hit the water but that's about it.

We have had a customer drive out here from cave country, with a set of LP85s filled to 4250, with 242bar valves on them, overfilled to the point that gas was passing past the oring and bubbling. Had they been caught sooner than getting to the site, we would have dumped them down to service pressure. Our lives and vessel are not worth someone trying to get a few extra minutes on a dive...

 

[grantctobin]

You are right. Its been a long few days and everything was a bit jumbled. 5250 is standard for HP tanks. Its our damn carbon cylinders that are like 6000 and 7500 respectively.

But we have seen PST Tanks fail before and the common denominator on them was that they were left full and overfilled. We dont need the extra gas so we dont overfill them anymore. We are a big advocator for buying the right size tanks and not trying to fit an elephant into a Horses body.

I will admit we do fill LP85s to about 3300hot because its super hot here in the summer and tanks rapidly cool when they hit the water but that's about it.

We have had a customer drive out here from cave country, with a set of LP85s filled to 4250, with 242bar valves on them, overfilled to the point that gas was passing past the oring and bubbling. Had they been caught sooner than getting to the site, we would have dumped them down to service pressure. Our lives and vessel are not worth someone trying to get a few extra minutes on a dive...

And that is with the PST prestretched as per proper procedure?

 

[Tracy]

But we have seen PST Tanks fail before and the common denominator on them was that they were left full and overfilled. We dont need the extra gas so we dont overfill them anymore. We are a big advocator for buying the right size tanks and not trying to fit an elephant into a Horses body.


We have had a customer drive out here from cave country, with a set of LP85s filled to 4250, with 242bar valves on them, overfilled to the point that gas was passing past the oring and bubbling. Had they been caught sooner than getting to the site, we would have dumped them down to service pressure. Our lives and vessel are not worth someone trying to get a few extra minutes on a dive...

I have only ever had one steel scuba tank fail a hydro that didn't also have obvious visual issues. It is still a mystery to me. I still have the tank. It looks perfect, no signs of heat, but the steel is completely brittle.
I know it happens, I see it often with bulk gas bottles that have never been overfilled. The main issue is quantity, the shop processes about 10,000 bulk bottles per year and around 200 scuba. With numbers like that, obviously you will see more bulk tanks fail.
4250 is a ridiculous overfill. The valves and regulators are not designed for it and at that point, you are most likely doing actual damage to the tank.
A common overfill to 3600, that could even get near 4000 in the Arizona heat is a completely different animal. Even 4000 is working way to close to the line for me as I am the one buying the tanks and have no interest in replacing them.

 

[Jona Silverstein]

I have only ever had one steel scuba tank fail a hydro that didn't also have obvious visual issues. It is still a mystery to me. I still have the tank. It looks perfect, no signs of heat, but the steel is completely brittle.
I know it happens, I see it often with bulk gas bottles that have never been overfilled. The main issue is quantity, the shop processes about 10,000 bulk bottles per year and around 200 scuba. With numbers like that, obviously you will see more bulk tanks fail.
4250 is a ridiculous overfill. The valves and regulators are not designed for it and at that point, you are most likely doing actual damage to the tank.
A common overfill to 3600, that could even get near 4000 in the Arizona heat is a completely different animal. Even 4000 is working way to close to the line for me as I am the one buying the tanks and have no interest in replacing them.

Yeah and its also a completely different animal being a shop and most diving being a fair bit away. Tanks overfilled could be a massive DOT issue if they gave a ****.

4250 is fine if its an HP tank with a 300bar valve. We have some of the older Wrapped aluminum tanks that of course can no longer be hydroed so they are reduced to shop tanks but they are rated at 4500psi.