Propane tank pointers?

[kuribo]

My local scrap yard has 4-5 decommissioned 500 gallon propane tanks which they tell me they will sell to me for $180 each. They say that the propane company took them out of service and all the plugs are out of them. Any tips on what to look for besides holes???? Thanks....

 

[Hunderliggur]

Are the threads in the fittings useable? If they are you can use them for a lot of your piping. If they are dented they were badly abused. You are only talking 20PSI so the should be OK.

 

[RobC]

Look at the bottoms of tanks. That's where your likely to find the deepest rust pits. I also noticed that some of the tanks are of a thicker wall steel. Don't know how to tell on that, I only noticed when I picked them up on my loader.
Get 1 if you can that has a threads on bottom so you can drain tanks if your going with a stacking set up. Not all tanks have bottom threads.

 

[woodsmaster]

Are you going to stack horizontal or stand verticle ?

 

[kuribo]

Are you going to stack horizontal or stand verticle ?

If my basement had 12 foot ceilings, I would love to stand them up but since there isn't the head room, they would be horizontal.....

 

[Singed Eyebrows]

Tap on the bottom of the tanks with a 2lb hammer, you will be able to tell if they are partly rusted through, Randy

 

[DaveBP]

Tap on the bottom of the tanks with a 2lb hammer, you will be able to tell if they are partly rusted through

One of the tanks I got had apparently been left with an accumulation of leaves and dirt around the bottom and there was very noticeable rusting and some pitting there. I just drilled through the worst looking pits and found there was still 3/16" or more of steel there and I decided it would work for such low pressure as it would ever see.

Oh, and don't forget to weld up those holes!

 

[Singed Eyebrows]

Tap on the bottom of the tanks with a 2lb hammer, you will be able to tell if they are partly rusted through

One of the tanks I got had apparently been left with an accumulation of leaves and dirt around the bottom and there was very noticeable rusting and some pitting there. I just drilled through the worst looking pits and found there was still 3/16" or more of steel there and I decided it would work for such low pressure as it would ever see.

Oh, and don't forget to weld up those holes!

Yes, I was told by my tank builder that 3/16 is good for 60 psi working pressure with a safety factor much higher. Randy

 

[PassionForFire&Water]

This is a formula to calculate your minimum required tank wall thickness

t = ((P * D) / ((2 * S * E) + P)) + C

where:

t is minimum required thickness (inches)
P is your internal tank pressure (psi) - lets say 20 psi
D is your Tank diameter (inches)
S is the allowable stress for the steel the tank is made of. Take 15,000 or 20,000 psi
E is the welding efficiency factor. Take 0.7
C is a corrosion allowance for new constructed tanks

t = ((20 psi * 30 inches) / ((2 * 20,000 * 0.7) + 20)) + 0"
t = 0.0215"

I believe those tanks are designed for 220 psi gas pressure and have a thickness of 0.2"

Like Randy said, a small hammer, but a really small hammer, will give you a higher tone when the tank material is thinner, usually at the bottom of the tank if the tank was used horizontally.