Storing tanks in the heat

[osb]

Hello all,

I have a question about storing tanks in the heat. I recently realized that I left my three tanks (AL80) in the back of my black truck, under a black tonneau cover in the Texas heat for two and 1/2 weeks. (I know I'm a moron -- i thought i put them away in the guest room closet where I normally keep them) I'm not sure how hot it gets back there, but safe to say it's real darn hot !!


Any reason to think this might have caused any problems ? One is full, the other two have 1200 and 1800 respectively.


many thanks,
OSB

 

[redacted]

Assuming the "full" tank had a 3000psi fill and temps climbing into the 130 to 140 F range, pressure would have risen to around 3300 psi. Pressure is proportional to temperature on the Kelvin scale.

 

[osb]

Thanks for the reply-
I dont know if it got hotter than 130-140... i'd bet it did thought, but probably not that much more.

Beyond the max temp and pressure the tanks experienced, I was worried about the repeated stressing of the tanks over the 20 or so days they were back there.

any thoughts on what the AL80s can take in that respect ?

 

[DA Aquamaster]

Depending on the aluminum alloy used in your tanks, they can tolerate a maximum temp of 400 to 600 degrees F without any problem. Beyond those temps, they will be worth about $.25 per pound as scrap.

An aluminum tank is tested to 5/3rds its service pressure, or 5000 PSI in the case of a standard aluminum 80, and the burst disc assembly will blow long before that pressure is reached so there isn't a risk of blowing them up if they get too hot.

Converting degrees F to degrees K is a pain but as a rough estimate you can figure on a 6 psi increase in pressure for each degree F. So if your tanks were 70-80 degrees over standard temp of 59 degrees, the pressure was probably around 3400 to 3500 psi at 130 to 140 degrees.

Your tanks would still be well within tolerable limits even with the extended temp and pressure. Still it's not a good idea to let your tanks get that hot as the effects of repeated and perhaps extended periods in excess of the service pressure could cause fatigue problems down the road.

 

[redacted]

DA Aquamaster once bubbled...
.... So if your tanks were 70-80 degrees over standard temp of 59 degrees, the pressure was probably around 3400 to 3500 psi at 130 to 140 degrees.

In Texas, the standard temp is 80. At 59 we bring out the parka.

 

[cornfed]

awap once bubbled...


In Texas, the standard temp is 80. At 59 we bring out the parka.

A friend of mine grow up in Texas then went to school in Chicago. Now neither 100+ deg F nor subfreezing temps bother him!

 

[plsdiver4377]

awap once bubbled...


In Texas, the standard temp is 80. At 59 we bring out the parka.

Come to South Western NC you'll love it here in the Spring, frost in the morning then close to 90F by afternoon:wacko:. Gives the heatpump a workout. Had to buy a different controller that can handle both extremes. :mean:

 

[FredT]

DA Aquamaster once bubbled...
Depending on the aluminum alloy used in your tanks, they can tolerate a maximum temp of 400 to 600 degrees F without any problem. Beyond those temps, they will be worth about $.25 per pound as scrap.

The magic number for 60XX Aluminum tanks is 300-350°F for annealing to begin. Had it reached those temps the full tank would have vented, and the half full tank exlploded. The fact they didn't indicates the tanks are OK. I expect the max temps in the truck bed were in the neighborhood of 170-180° F. Have to do a themal budget to be sure, but at 70° above ambient the energy loss to radiation from the bed to the ground should be close to what incident radiaton can supply over the convection losses.

FT

 

[DA Aquamaster]

I wondered what alloy is used in scuba tanks. I know AA 6061 has a max recommended temp of 400 degrees befre the heat treatment is affected.