Overpressurizing / Overfilling steel tanks

[HarleyDiver]

LP steel tanks (2400+ or 2640 rated) are regularly filled to 3000+, often filled to 3500, and sometimes filled to 4000(check your burst disk).

However in a lot of places (Key Largo being one) you are lucky to get them filled to 2600. If you want over-fills you have to DIY or find someone who has been using steel long enough to understand the issues.

But don't expext anyone to post names of places to get them filled on an open public forum.

 

[Scubaroo]

Aluminum tanks should not be overfilled, period.

Overfilling of steel tanks however is quite common in parts of the world.

I know you said no preaching, but I thought it was worth pointing out seeing as you had mentioned overfilling and aluminum tanks in the same post. Others reading this might not be aware of the distinction between overfilling aluminum and steel.

 

[DiveTub]

I dont overfill my Ally or Steel tanks.
I make sure I have the right sized tanks to do the job without needing to overfill it.

 

[gjmmotors]

someplaces in florida will fill your lp steel just about as high as the compressor can pump or your burst disc will hold.
burst plugs work well.
If your situation is that of a non overhead environment and size of tanks is not a concern. Than go for the big twins.
Or stages.
-g

 

[SADivemaster]

Quite humorous watching all the whinning...

Also quite humorous was watching a good friend of mine, well known for his bravado that borderlines stupidity almost soil himself when his burst disc decided to give way during a hydrostatic test. Bloody fool.

I'm sure most of you have seen similar pictures, but for those of you that haven't. The owner, or should I rather say the previous owner, had left his cylinder in the boot (trunk) of his car for a few days. One hot day in the sun finished it off.

G

 

[SADivemaster]

and his car...

 

[roakey]

SADivemaster once bubbled...
Also quite humorous was watching a good friend of mine, well known for his bravado that borderlines stupidity almost soil himself when his burst disc decided to give way during a hydrostatic test.

Say what? The valve is removed for a Hydrostatic test, therefore no burst disk. Also a complete catastrophic failure during a hydrostatic test is undetectable outside the measuring container. It's barely detectable INSIDE the measuring container, for that matter...

Roak

 

[SADivemaster]

The pillar valve wasn't removed for the hydrostatic test.
What pray tell is the point of testing only the cylinder, when a potential problems could lie withing the pillar valve itself? A chain is only as strong as its weakest link.

 

[DA Aquamaster]

SADivemaster once bubbled...
....when his burst disc decided to give way during a hydrostatic test. G

I'm not unerstanding this one... The valve (with the burst disc in it) is not even in the tank during a hydro test, so one won't "let go" during a hydrotest.

If anything "lets go" in a hydro test it is a non event as the tank is water filled. The most spectacular failure I have seen is water squirting out a crack in the shoulder when the tank was removed from the test cylinder. It was a "gee whiz isn't that neat" moment but not even remotely scary.

SADivemaster once bubbled...
....the owner, or should I rather say the previous owner, had left his cylinder in the boot (trunk) of his car for a few days. One hot day in the sun finished it off.G

This was does not entirely make sense either - the burst disc will let go long before the tank and prevent this type of failure. Tanks go to 5/3rds (or 3/2's in some cases) the service pressure in a hydro test and a burst disc will fail long before this pressure is reached.

The exception would be if the Aluminum tank had been exposed to a fire and temps in exess of 300 - 350 degrees. Trunks don't get that hot, even in August in direct sunlight so there is more to the story than just leaving it in the trunk.

 

[SADivemaster]

Different countries do things differently. Here in South Africa I have had hydro's done with the pillar valve attached, IOW, the tank is pressurized to test pressure through the A-clamp/yoke fitting, unlike the US standard of removing the valve and inserting the M25 thread (or the imperial version thereof) from the compressor directly to the tank itelf, in place of the pillar valve Thus creating a situation where the burst disc ruptures at higher than normal working pressure, causing the pressurized water to squirt out.