Overpressurizing / Overfilling steel tanks

[DeepScuba]

Thanks for saying it first DA

I was going to say that there's no way in hell that a tank in good condition could blow up in a trunk on even the hottest of days, but I didn't need the abuse that was sure to follow.

There's no mathematical way it could happen, unless you're of course talking Nuclear Bomb type heat, which I can assume didn't happen.

I'd be curious as to the REAL story.

LPSteels, double disked, regularly pumped to 3300PSI. So I will only get 10,000 fills before it fails vs. 30,000, so who's gonna do 10,000 dives on a tank anyways?

I can't remember were I read that, maybe someone here has read the same thing.

 

[Genesis]

don't overfill either.

Do hot fill both off the compressor, but never beyond where the calculated cooled pressure exceeds the service pressure by more than 100 psig.

The usual AL80 hot fill that I do is to 3200, with final "cold" pressure right at 3000. 3442 HPs get filled to ~3750, and cool to right near 3450.

You can overfill your tanks if you want. I'm well-aware of how much energy is in a filled tank and have no desire to release it all at once.

 

[Dryglove]

Will you fill my cylinder to more than its rated maximum pressure?

Fill Express does not overfill any aluminum cylinder. Overfilling shortens cylinder life, as well as increases risk of cylinder failure. Increased pressures also can cause burst disks, O-rings, and 1st stage regulator seats to unexpectedly fail prematurely. Willing to accept these risks in exchange for the increased gas volume, technical divers sometimes overfill their meticulously maintained steel cylinders. Upon request, Fill Express overfills those privately owned modern chrome molybdenum steel cylinders that we find to be in excellent condition. We will fill a low-pressure (2640 psi) cylinder up to 3000 psi if it has a yoke valve and up to 3500 psi if it has a DIN valve. We will fill a high-pressure (3500 psi) cylinder with a 300-Bar DIN valve up to 4000 psi; this requires that the cylinder be left with us to cool and then be topped off to 4000 psi. At this time, we will not overfill the new PST E-series (3442 psi) cylinders. Fill Express may refuse to overfill a cylinder for any reason; the final decision rests solely upon the fill station operator.

This came from a very popular fill shop in florida.
http://www.fillexpress.com/library/fillfaq.shtml#policy

 

[Dryglove]

Hydro Test Pressure (psi) : 4000 psi

Minimum Burst pressure (psi): 6400 psi

Material: 4130x Chrome Moly

Testing: (a) Ultra Sonic (b) Hydro Test

Design Life: 10,000 Cycles at 4000 psi


http://www.omsdive.com/cyl_spec.html

 

[Whitelightnin]

How about the older steel 72's (2250 psi)? How high will you fill these?

 

[Whitelightnin]

I currently use oxygen tanks for storage banks on my steel 72's. They (oxygen tanks) are rated for 2250 psi. I fill them to 2500 psi. I have heard of people using them as storage banks & filling them to 3500psi. Does anyone on here know of this being done?

 

[Scuba_Vixen]

They are not made from chromium-molibdenum (chome-moly) alloy.

Check any of the cave country fill places, noted for overfills, and they'll tell you the same thing.


Darlene

 

[HarleyDiver]

Can who ever moved this thread enlighten us as to why a NEW thread was moved and stuck on the tail end of a 2 year old thread?

If you start combining all similar threads there will only be 20-30 left. I can see 1 giant DIR/Anti-DIR thread with 3 million posts...

 

[roakey]

HarleyDiver once bubbled...
Can who ever moved this thread enlighten us as to why a NEW thread was moved and stuck on the tail end of a 2 year old thread?

If you start combining all similar threads there will only be 20-30 left. I can see 1 giant DIR/Anti-DIR thread with 3 million posts...

It was me.

This is to avoid fragmentation of information, if we have one overfilling note, people will have one stop shopping for overfilling information.

If people would learn to use the search function, combining notes wouldn't have to be done in the first place; in many cases they'd find that their questions already answered and would have the answer instantly instead of posting the question for the zillionth time and only getting a few responses from the newer folks that haven't already answered the same question 50 times.

This of course is bad news for folks who like answering the same question over and over and over and over again (show of hands?) and good news for people that look at this file as an information resource, and not just a idle chat board.

Roak

Ps. And by using the first unread reply functionality you'd skip over the old notes anyway, so what's the problem?

PPs. And actually I collapsed about 5 redundant overfilling notes into this one thread, including the latest, redundant post.

 

[Epinephelus]

Tanks have variable safety factors built into the manufacturing process. Steel is elastic, aluminum is essentially not. The older steel tanks aren't as elastic or resilient as the newer ones. The chances of getting bit overfilling a relatively new steel LP tank are very nearly infinitesimally small; moderately overfilling a steel 72 (3000 psi) isn't likely to cause a catastrophic failure; even slightly overfilling aluminum tanks isn't likely to be a problem.
But...
The intentional overfilling of tanks reduces the margin for error in all cases, so while I don't have a cow if the shop rat slips up and overfills my steels (even my old 72's), I don't overfill intentionally, and I don't recommend any of you overfill intentionally.
E.