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Propane Tank Question
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So a friend of a friend that is fairly local has a bunch of 500 gallon propane tanks that he will let go cheap. At least cheap for my area, based on CL pricing.

He said some have some pitting on them. Does this matter?

He's sending me a bunch of pics later today.

My plan is to buy MM500 and dehydrator plans and use them for it.
 
Location: NPR, Florida | Registered: January 29, 2010Reply With QuoteReport This Post
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As long as the tanks have enough structural integrity to meet your purposes -- i.e., don't leak, and will hold whatever vacuum or pressure you intend to put on them -- I can't see where pitting would matter. It's probably just external surface ugliness. Hit it with a sander or flapper disc when you're done with your modifications, paint it, and go. All the usual cautions that go along with working on a former propane gas tank apply.

Good (large) propane tanks can be hard to find cheaply around here because everyone turns them into barbeque / smoker projects! Sounds like you have a good lead.

Cheers, John
 
Registered: June 17, 2007Reply With QuoteReport This Post
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What John said...
Unless the pitting is 3/16" or deeper I wouldn't give it a second thought...
My 500 gallon tank is from the early 60's, besides the heavy pitting around the legs there was about 300 layers of paint on it, some of it was toxic lead paint I am sure. I would have taken more pitting over all the old paint in a heart beat! Roll Eyes Its been holding up just fine...
Cheers,
Jon
 
Location: Wellington County, Ontario Canada | Registered: February 07, 2008Reply With QuoteReport This Post
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A little pitting won't hurt, as long as they are not rusted half way through, they are typically 3/16" thick.
 
Location: West Michigan | Registered: April 26, 2006Reply With QuoteReport This Post
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Cool, I will check how deep it is.

So I read a thread to fill it with water and roll it around and empty - repeat three times. Then do it again with water and a gallon of bleach and let sit for a few hours to get rid of any smells.

Still the plan to prep it?
 
Location: NPR, Florida | Registered: January 29, 2010Reply With QuoteReport This Post
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I won't repeat all the safety stuff here. You can and should do that research on your own, above and beyond just getting rid of the stinky smell. Safety is like an internet conversation about which engine oil is best... I'll just say that my personal policy is that before I take a torch or a welder to any tank, it is completely filled with water and any existing holes/fittings are wide open.

Cheers, John
 
Registered: June 17, 2007Reply With QuoteReport This Post



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I actually read it here, but it was a couple years old. So I didn't think nothing about posting. Didn't know it was a big deal.
 
Location: NPR, Florida | Registered: January 29, 2010Reply With QuoteReport This Post
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No offense intended and certainly none taken. I was just pointing out that welding on old propane tanks is a very hot topic on the internet if you start looking into it and do a few searches. Opinions range all the way from "don't do it no matter what, you'll blow yourself and your whole neighborhood up!!" clear to the other end of "just hold my beer while I light her up, it'll be fine." What constitutes "safe enough" is a very individualized decision -- I gave you the Reader's Digest version of what is safe enough for me. That was my only real point there.

How to get the indicator smell out of tanks is another conversation, which I'm not too familiar with -- I don't particularly care if mine stinks a bit inside. I have found that the smell fades on its own with a few cleanings, uses, fill-and-empty cycles, etc. A professional welder friend of mine likes to use powdered laundry detergent and water for that purpose, just rolling the tanks around now and then while it soaks for a couple of days.

Good luck with your MM500 build. Please post updates and pictures, as we enjoy seeing others' projects go together.

Cheers, John
 
Registered: June 17, 2007Reply With QuoteReport This Post
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All of my plans which involve the use of a propane tank contain instructions and guidelines on how to make them safe to work on.

In all of the plans I have sold, and don't forget my heaters use propane tanks too, there has never been a single accident. Not even a close call.


www.MurphysMachines.Com
The best Do-it-Yourself Construction Plans on the Internet!
Waste Oil Heating - Biodiesel Systems
Biodiesel Pumps Made In The USA
 
Registered: March 09, 2006Reply With QuoteReport This Post
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I'm reasonably sure that Murphy will sell his plans to 'everyone'. He's always shared his significant advances in biodiesel production technology. He's one of the more helpful vendors out there. There is no good reason for Murphy [or anyone else] to give any of their intellectual property away for free.



 
Location: coldest N.America | Registered: May 03, 2005Reply With QuoteReport This Post
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My instructions say to use Hydrochloric acid (muriatic acid) and water... let sit for a day or two, rinse tank out.. (be sure to neutralize waste water)

Bleach works good too but not as well as the acid.. While bleach will clean out the propane, it will not touch the mercaptan (sp?) smell..
The tank could be perfectly safe to work on (or not), but it will still smell like its full of propane..


I can't tell you how many times I've had people tell me they just drag them into a field and set them on fire. That's one way to get the propane out! But darn, I would never recommend that to anyone.

Others fill with water then cut.. Works good but then you have to deal with 500 gallons of water pouring out through the cut.

And others will send engine exhuast into the tank.. the theory is that it displaces the oxygen so the propane can't ignite. This also works but not something I recommend due to the ease at which it could fail.

I don't consider issues of safety to ever be proprietary and I will always go out of my way to help others stay safe. (Lets not forget my one-and-only appleseed float switch!)

Hope that helps,


www.MurphysMachines.Com
The best Do-it-Yourself Construction Plans on the Internet!
Waste Oil Heating - Biodiesel Systems
Biodiesel Pumps Made In The USA
 
Registered: March 09, 2006Reply With QuoteReport This Post
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Nicely done Murphy!

Thanks,

Bob


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Location: Moncure, North Carolina | Registered: April 21, 2001Reply With QuoteReport This Post



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I would like to add to Murphy's instructions.

LPG is heavier than air so after venting the tank and removing all the fittings you need to Turn the tank upside-down and allow it to remain in that position for a day or two to allows the propane gas to drain from the tank.

LPG is odorless and colorless so the gas methyl mercaptan is added which gives it it's rotten egg smell. The mercaptan smell will linger in the LPG bottle long after all the LPG is gone.

Another thing you need to be aware of is that because most LPG is produced by the petroleum industry, apparently, over time there may be small amounts heavier hydrocarbon contaminates enter the tank.
If you are drawing the LPG off the tank as a gas rather than a liquid which is usually the case, these heavier hydrocarbons may build up in the tank over time. This may be part of the liquid that often comes out of the LPG tank bottle in small quantities after you turn the bottle upside down.

These heavier hydrocarbons are also inflammable and need to be taken into consideration.

After allowing the Tank to remain upside down for a couple of days to drain the LPG, many people like to wash the tank out with soap and water just in case there are any remaining hydrocarbon liquids and to help reduce the stink of the mercaptan.

The second last step is to completely purge the tank. As per the bulletin listed below "Purging can be accomplished with the use of inert gases, steam, or by completely filling the cylinder with water."

The last step is to ALWAYS use a gas monitor as a final check for safety.

Remember, you are the sole person responsible for your safety and the people around you. You assume all the responsibility if anything goes wrong.

If you have any concerns at all as to whether you can perform a procedure safely, spend a few dollars and have a professional do it for you.

This information comes from the National Propane Gas Association bulletin #132-91,
Recommendations for the disposition of unservicable LP-gas cylinders.
"Thoroughly purge the cylinder before making any attempt to destroy it with a cutting torch or other device. Purging can be accomplished with the use of inert gases, steam, or by completely filling the cylinder with water."
"Once the cylinder pressure has been reduced to the atmosphere and the cylinder has been purged, a test should be performed to verify that it is free of a combustible gas mixture before disposal. A combustible gas detector may be used for this purpose".
 
Location: Louisiana | Registered: February 17, 2013Reply With QuoteReport This Post
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