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Cutting the bottom off a propane tank?


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  #21  
Old 03-23-2008, 09:47:23 PM
mooseye mooseye is offline
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Default Re: Cutting the bottom off a propane tank?

I know this is an old post, but I joined this board because of it.
Do not use a cutting torch to cut open any kind of container. Even if there is an opening, the unburned fuel from your torch can accumulate in the container and mixed with the oxygen from the torch will create an explosive. In my state, it is not only dangerous, it is against the law.
It is not residual from what ever was in the tank,although it can be, it is what accumulates while the cutting process is going on.
I know there are those saying "I have done that a hunred times with no problem. Well, it only takes one time and you could end up like a friend of mine who was cutting open a barrel and is now called three fingers.
A cold cutting method, such as a band saw, is the safest way. The local propane revitalization plant here uses a lathe.
Sorry if this seems offencive to anyone, but i don't like to see anyone hurt.
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Old 03-23-2008, 11:04:47 PM
Andrew Mackey Andrew Mackey is offline
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Angry Re: Cutting the bottom off a propane tank?

Here in NJ, to scrap a flammable gas bottle, the brass fill/stop valve must be removed, and 3 - 3/8" holes drilled thru the bottom of the cylinder. Oil in the propane tank comes from propane itself. As propane is a manufactured gas, slight amounts of oil vapor are suspended in the liquified gas. As you use the gas, the liquid fuel boils off, leaving the oily residue in the tank. This is one of the reasons the feds put on the new anti tip valves on tanks, and made it illegal to refill the older ones, to prevent people from re-filling the 14 ounce bottles from the 10 and 20 pounders. A lot of times, when the larger tanks were inverted to fill the smaller ones, the oil would freeze in the valve of the small tank. When it melted, voila - you got a rather large cloud of vaporized propane gas - usually in a confined space. The result - BOOM.
Andrew.
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  #23  
Old 05-05-2008, 10:38:03 AM
woodchuck53
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Default Re: Cutting the bottom off a propane tank?

Morning, we have always pulled all plugs and bungs. Fill with water and have it out in the pasture for safety, soak a scrap pc. of grass string in charcoal lighter and string it out. Light off and let it flash the vapors. Let it sit after draining for a day or so and try to light it off again. Then just fire the torch up and cut. This has always worked for me. As always approaching something like this it boils down to confidence. If in doubt let a professional do it. CV
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  #24  
Old 05-05-2008, 01:37:45 PM
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Randy Hart Randy Hart is offline
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Default Re: Cutting the bottom off a propane tank?

I would rather take my chances on an old freon tank and weld whatever nipple I need after the fact..

Randy
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  #25  
Old 05-05-2008, 10:16:15 PM
John A John A is offline
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Default Re: Cutting the bottom off a propane tank?

If you hear the blast you have problems.
If not.....you have nothing to worry about...Make sure life insurance is paid up. lol.
John
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  #26  
Old 05-06-2008, 06:41:00 AM
J.B. Castagnos J.B. Castagnos is offline
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Default Re: Cutting the bottom off a propane tank?

When my brother was in the army they had a class on explosives. He was told you could tell when a bomb was about to explode. "You'll see the case expanding".
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  #27  
Old 05-10-2008, 09:50:05 PM
weldingshop weldingshop is offline
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Default Re: Cutting the bottom off a propane tank?

I once scraped a fuel tanker, a tractor trailor size fuel tanker which was used to transport gas...............We filled it with water and began cutting......with oxy acet...........
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  #28  
Old 07-01-2011, 10:17:49 PM
MidGAOutdoor MidGAOutdoor is offline
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Default Re: Cutting the bottom off a propane tank?

i have mine sitting out there filled with water so that there is no air in the tank. is i safe to cut while filled with water?
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  #29  
Old 07-01-2011, 10:42:33 PM
trowel
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Default Re: Cutting the bottom off a propane tank?

no, the gas can collect above the water, purging the tank is better,
on 20 gal. tanks i drained the tank of all gas, clamp it in something sturdy, then remove the valve with hand tools, not power tools, then purge the tank with oxygen or the likes, then use power tools,
i have made propane forges and wood/coal stoves using the shell lined with refractory liner,
i found this to work good for me, but always be alert that some gas may still be in the tank and the valve pointed in a safe direction,
trowel
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  #30  
Old 07-02-2011, 11:38:30 AM
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OTTO-Sawyer OTTO-Sawyer is offline
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Default Re: Cutting the bottom off a propane tank?

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Originally Posted by trowel View Post
..., then purge the tank with oxygen or the likes, then use power tools,...trowel
Even using power tools instead of a torch, wouldn't it be better to purge the tank with Argon instead of Oxygen.

Concidering Steel Wool BURNS in pure oxygen, and fine powder or dust of many materials can explode (like sugar refineries blowing up), I would think 'purging' a tank with oxygen and then cutting it with fine particles of metal flying around inside is asking for trouble if you create a spark while cutting (even a static electric spark)

Granted (I was stupid enough to do it) I cut open 3 automobile gas tanks with a metal cutting blade on the skill saw last month with all the sparks shooting inside, but they were well venilated with several large holes, and no extra oxygen introduced into them. I also made sure ahead of time that there were no gas fumes and after dribbling what little liquid was in them into a small can and pointing a blow torch in the can to see if it would burn, I felt relatively safe (or just dumb) enough to go for it.

I wouldn't recomend anyone else do what I did (not knowing myself what may be in their tank), but I definitely wouldn't use a torch. We had an old guy in my area that was killed 25-30 years ago cutting the tops off of 50 gallon drums for burn barrels using a torch. He'd been doing it for years with no problems, but finally had one blow up on him. Spent a few very painful days in the hospital before he died. Not a good way to go.
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  #31  
Old 07-02-2011, 12:32:55 PM
Ironsides Ironsides is offline
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Default Re: Cutting the bottom off a propane tank?

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Originally Posted by Ray Freeman View Post
I have welded fuel tanks after draining them and rinsing them out with water and detergent. Then run the exhaust of an engine through it for 20 minutes.
As long as you get the oxygen out of it and have it purging with inert gas there is not a problem.
Ray,the only thing I would add is to leave the hose in the item you are going to cut and leave the vehicle running whilst you doing these tasks,worked for me when we had to bronze up a hole in a petrol drum,Norm
PS does not work well, indoors
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  #32  
Old 07-03-2011, 01:21:25 AM
Bill Feasal Bill Feasal is offline
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Default Re: Cutting the bottom off a propane tank?

A couple of weeks ago I scrapped a old 20# tank and the yard wanted it cut in two pieces. I pulled the valve let it set in the sun or 3 days put a small loose fitting pipe in it with low pressure air flow to keep the gas fumes from building up. Let that run for 2 hrs. the used a saws all with a hack saw blade. it worked and Iasm still here
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  #33  
Old 07-03-2011, 06:19:31 PM
K D Redd K D Redd is offline
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Default Re: Cutting the bottom off a propane tank?

This story was related to me by a guy who mechanic for a construction company. They were needing a 500 gallon water tank FAST. They had a unused 500 gallon LP tank with some LP in it. The vented the LP, removed all of the valves and put about 10 lb of Dry Ice in to the tank. They waited about 15 Minutes. then a welder used a cutting torch to cut the needed holes for the water tank conversion.
You need three things for a fire/explosion. You need fuel, a oxidizer, and you need heat. This is the Fire Triangle. With Dry Ice you cut off two of the three legs of the fire triangle. You do not have a oxidiser. The CO2 from the dry ice being heavier than air displaces the 22% O2 that in in the air and you have reduce the amount of heat in the system because the Dry Ice chills the inside of the tank.

Kent
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  #34  
Old 07-03-2011, 06:51:05 PM
trowel
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Default Re: Cutting the bottom off a propane tank?

thanks otto-sawyer, but i would be carefull using argon,
i use argon to weld with, is it really a safer gas?, think about it,
PURE oxygen burns metal, i had one to blow open the tap hole on my cupola furnace when it cloged, called a blow lance, if i held it too far away the outside air will mix with the oxygen and it would not work,
after removal of the valve and purging with oxygen you are also letting in regular air from outside, the oxygen that was just blown in is no longer pure, a large air compresser would do just fine too blowing the gases out, then washing the inside of the tank with soap or letting the tank sit for a few days after purging works too,
do you know how many gas tanks i have cut open??
forges, coal/wood stoves, buckets, steel wheels, the moldboard of my ditcher, patching mower decks, etc.....i could go on,
those tanks are very good steel,
next time ask me a question before you use my post against me, im just trying to help someone with something that is dangerous,
trowel
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  #35  
Old 07-03-2011, 09:29:50 PM
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Default Re: Cutting the bottom off a propane tank?

Wasn't trying to "use your post against you" . Didn't know if it was a typo, or if you meant it that way.

Fires burn hotter with more oxygen added as in cutting torches or even just using a blower on a forge to blow more air and therefore more oxygen into the coals.

Argon is a shielding gas not a cutting gas.

As for how many tanks you've already cut safely, it could be many more, or not quite as many and the old guy I knew that was killed after cutting just one more 50 gallon drum for a burn barrel after doing the same thing hundreds of times over 50-70+ years without incident.

It's always the Last One that gets you.

No Offense intended, I'm just trying to help people too.

Alan.
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  #36  
Old 07-03-2011, 10:12:28 PM
trowel
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Default Re: Cutting the bottom off a propane tank?

none taken,
i get cranky when it rains, leg is hurting today, i had one tank take off on me once, went 30 yards or so,
scary!
argon needs to burn to shield the weld from oxygen, much more combustable then oxygen,
pure oxygen is mixed with propaine or acetylene for cutting torches, without oxygen torches would be worthless,
i went to school for 4 years and have years of welding behind me, and im shure you have too,
im also a part time blacksmith/metalsmith and use to cast aluminum and gray iron before selling it all and moving to mass.
blah, blah, blah, blah, rant, rant, rant, i'v done this, tried that, whatever! so have you,
it's the 4th of july, a real american holiday, let's all enjoy it,
cheers, and be safe,
trowel
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  #37  
Old 07-03-2011, 10:30:26 PM
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OTTO-Sawyer OTTO-Sawyer is offline
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Default Re: Cutting the bottom off a propane tank?

My "Thanky button" is all burned up right now, but I'll try to catch you later on that one, as I guess maybe I learned something there....

I didn't know that Argon burned to make the shield. I thought it was an inert gas that didn't burn.

I gets all cranky too sometimes. Rain don't bother me, but a sudden pressure drop leading to weather changes makes every joint in my body ache.

Last edited by OTTO-Sawyer; 07-03-2011 at 10:32:45 PM. Reason: added a line
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  #38  
Old 11-03-2011, 10:30:00 PM
tsalconoci tsalconoci is offline
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Default Re: Cutting the bottom off a propane tank?

Quote:
Originally Posted by trowel View Post
none taken,
i get cranky when it rains, leg is hurting today, i had one tank take off on me once, went 30 yards or so,
scary!
argon needs to burn to shield the weld from oxygen, much more combustable then oxygen,
pure oxygen is mixed with propaine or acetylene for cutting torches, without oxygen torches would be worthless,
i went to school for 4 years and have years of welding behind me, and im shure you have too,
im also a part time blacksmith/metalsmith and use to cast aluminum and gray iron before selling it all and moving to mass.
blah, blah, blah, blah, rant, rant, rant, i'v done this, tried that, whatever! so have you,
it's the 4th of july, a real american holiday, let's all enjoy it,
cheers, and be safe,
trowel
Argon doesn't "burn." You're flat out wrong. It is an inert gas that is used as a shield gas to prevent oxidation or other reactions with the atmosphere. The selection of a shield gas can impact the quality of the weld with Helium and Argon being the two inert "noble" gases used in welding. Further, argon is more dense than air and thus will settle down to keep a blanket of inert gas over whatever surface. This is particularly useful when working with extremely reactive and sensitive chemicals. The point is, it doesn't react with anything to "burn," oxidize, react, or anything else except under very specific circumstances using the strongest oxidizer known, fluorine. (In August 2000, the first argon compounds were formed by researchers at the University of Helsinki. By shining ultraviolet light onto frozen argon containing a small amount of hydrogen fluoride, argon fluorohydride (HArF) was formed.[2][16] It is stable up to 40 kelvin (−233 °C). The ArCF2+
2 metastable dication was also observed.[17])

Nitrogen is semi-inert and is also used for this purpose but it lacks the advantage of density and non-reactivity. CO2 is also semi-inert because the carbon is completely oxidized, but more reactive than N2, and thus not used to blanket reactions.

"argon needs to burn to shield the weld from oxygen, much more combustable then oxygen"
Now, filling a metal cylinder up with O2 and cutting it?
First, neither are "combustible." As previously stated, Argon is inert and O2 is an oxidizer. With out something to oxidize (burning is an oxidative process), oxygen won't do anything. Without a fuel nothing will happen in the presence of O2, but if you add something that can, like say unoxidized metal in the bottle being cut or some other flammable material in the area, the higher the concentration of O2, the more likely there will be a fire. Check the interwebz for stuff like this: http://www.youtube.com/watch?v=2y4gLhh0Zsk

Now, I don't have the welding experience you claim to, but I went to school for 3.5 years after high school and came out with a BS in Chemistry and was a bench chemist for DuPont.
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Old 11-03-2011, 10:51:20 PM
JHFoster JHFoster is offline
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Default Re: Cutting the bottom off a propane tank?

Quote:
Originally Posted by Andrew Mackey View Post
This is one of the reasons the feds put on the new anti tip valves on tanks, and made it illegal to refill the older ones, to prevent people from re-filling the 14 ounce bottles from the 10 and 20 pounders.
I thought they were called OPD's---overfilling prevention device? Here is MS, and I assume under Fed law also, one can still fill without the OPD's for certian reasons.
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Old 11-04-2011, 08:19:22 AM
PTSideshow PTSideshow is offline
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Default Re: Cutting the bottom off a propane tank?

DO NOT FILL A PROPANE TANK WITH PURE OXYGEN UNDER ANY CIRCUMSTANCE BEFORE CUTTING WITH ANY MEANS AS ONE LITTLE SPARK COULD SET IT OFF

First if oxygen burned as you claimed we wouldn't be here considering that the air we breathe and the atmosphere around our planet is made up of 21% oxygen.

You really need to either use the search engine function in your web browser and or a good basic welding book and read it before getting on a forum and making statements that are dangerous and can result in getting people killed or hurt.

You are lucky you haven't killed your self pumping pure oxygen into propane tanks and then cutting them!
Propane is explosive when mixed with oxygen or air, as you can see it doesn't take much for it to be set off!
EXPLOSIVE LIMITS IN OXYGEN 2.4% to 57%
EXPLOSIVE LIMITS IN AIR 2.1% to 9.5%


Quote:
argon needs to burn to shield the weld from oxygen, much more combustable then oxygen,
Argon is an inert gas as the label states on the cylinders, It doesn't burn or oxidies.

Argon is frequently used when an inert atmosphere is needed. It is used to fill incandescent and fluorescent light bulbs to prevent oxygen from corroding the hot filament. Argon is also used to form inert atmospheres for arc welding, growing semiconductor crystals and processes that require shielding from other atmospheric gases.

argon information

Quote:
PURE oxygen burns metal,
Oxygen doesn't burn burn in the normal sense, It is an OXIDIZER when it is mixed with a fuel gas it aids in the almost complete combustion of the fuel gas. It will drastically increase the speed at which burning(oxidation takes place)

Quote:
i had one to blow open the tap hole on my cupola furnace when it cloged, called a blow lance,
The following is how it operates.
The oxygen in combination with the preheated steel results in rapid oxidation of the surface. The oxygen jet blows the reaction products there by cutting the metal section. When cutting comparatively lighter sections, the preheating torch is removed, once the oxygen for the lance is turned on.
oxygen lance cutting

And yes to the statement about the cylinders and propane storage tanks have to either be cut in two or large holes have to be cutting in the sides.
It is to keep stupid people from getting them out of the scrap yard and putting new valves on them and reusing them!

If you want to repurpose a propane tank.
Washing it out with a grease cutting detergent like "Dawn" to remove the oils/sludge that can collect in old tanks.
It will also remove most of the odorant that is added for leak detection.
Some fill the tanks with an inert gas, argon, nitrogen, CO2 or even exhaust for an internal engine.THIS IS DONE TO DISPLACE THE OXYGEN IN THE TANK, SO THE EXPLOSIVE LIMIT MIXTURES ARE NOT REACHEDMaking it safe to cut with your choice of tools.
The dry ice method will also displace the oxygen so the explosive mixtures aren't reached. With the smaller tanks that don't have hand holes getting the dry ice in side is a pain as the pieces have to be small enough to go through the hole for the valve.You can add some warm water to speed up the process.
Filling with water and cutting with pneumatic grinders or saw can be done.
Propane 101 safety tips and more than most care to know from an industry group

Finally, If you are thinking about cutting propane tanks, inert gas or oxygen cylinders for gongs or other art work, or oil tanks for BBQ's or repair of fuel tanks.
You have to know the proper way to do it, if you are not comfortable with any of the options. Then the best thing is to either find another option large dia pipe, have a section rolled to your specs or find a local shop that does gas?fuel tank repairs. Some will cut the cylinders and tanks as a side line.

---------- Post added at 07:55 AM ---------- Previous post was at 07:32 AM ----------

Here is a link to a news story about a high school shop class making BBQ's out of drums and cutting same.

They were using MT peppermint oil drums. Peppermint oil is not only flammable but will generate heavier than air explosive vapors when heated only slightly. It is also allergenic and produces toxic fumes if burnt.

Sadly the latest news is the student didn't make it.

Link to news story

When cutting any closed container you can do the following which, I have come to believe to be a safe and inexpensive method.
Put a couple of pounds of dry ice in the drum and wait 15 minutes. Cut away. As safe as it gets with no other problems. If you fill it with water you have to dispose of the water afterwards as hazardous waste.

You would be amazed at the food additives that in small amounts are ok, but when in bulk are a different matter all together.

No the above is the case that proves the my point in my previous post. They cut other of this type drums before. They didn't (teacher) do any searches for information. All they wanted was a clean drum to make BBQ's out of.
Food safe drums and most other drums have a epoxy type lining or coating to prevent the contains from interacting with the drum material. it is very hard to remove.
Normally it is burned out when the drums are being cleaned and recycled.
Federal guide lines on recycling drums and barrels
from the site
Quote:
Rinse waters will contain the residues from the drums; therefore, segregation of incompatibles and proper treatment of rinse water is essential. Wastewater from drum rinsing may require special treatment depending on test results of the rinse water.
The point about the rinse water is your neighbors may be a real green weenie and turn you in. Since a lot of the members may have a city type living situation.

You have to know what you are using either the equipment, or materials for repurposing.

---------- Post added at 08:19 AM ---------- Previous post was at 07:55 AM ----------

For those that don't know here is a basic explanation of D.O.T. hazardous materials placards that are mandatory on containers, packages and trucks, ships and trains.

This includes the stickers that are mandatory on all cylinders of compressed gas. including propane.
Hazardous Material Placards basics
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