How to??? Purge propane tank?

[10 ga]

Have an old 20# propane tank that has the old fashioned round valve handle and plan to convert to smelting pot. How best to purge and make safe to cut with "wheel". Is it possible to get the brass valve fitting out/off? That would be a sure way to make safe. Got to be some experience with doing this out there. Thanks, 10 ga

[Johnch]

I did one a few weeks ago

I took the tank to the range and put 2 223 rounds sideways through the tank at the top
As I could not get the valve off

I then submerged it in water ( in a trash can ) completely fillling the propane cyclinder

I then drained it and while still wet
I used a Sawsall to cut the tank where I wanted

Probely a easyer way
But I used what was at hand

John

[JIMinPHX]

You can unscrew the old fitting, but that doesn't make it safe. You will still have vapors inside & that is enough for an explosion.

Even after you vent out all the gas, you will still have mercaptan residue inside. You will be able to tell by the smell.

If you fill it with water, it should be safe to cut, other than that, you need to seek guidance from someone that has mercaptan specific experience. I have a lot of tank demolition experience, but not a lot of mercaptan related experience.

[Fugowii]

Is there a purge screw in the side of the valve? There should be. I just did this to make my
smelting pot. I left the purge screw open overnight. The next day I put a pipe wrench on the
valve and took a hammer to it. It will loosen. My guess is that they put thread locktite on the
threads to prevent it from loosening. I then tipped the tank over and left it for a few days as
propane is heavier than air and it will vent out the open valve hole. Save the valve for the
junkie as it is brass (or should be). You will not get rid of the stink until you actually melt
some lead in it.

See this thread (post #25) on my adventure with a propane tank.

http://castboolits.gunloads.com/show...t=84678&page=2

[MT Gianni]

Use Clorox or a similar bleach in strong or pure quantities to equalize merco-captan. Let it soak for a few days. I would thread the top back on one or two turns if the odors are bad. Swirl it around a couple of times a day for 2 days and it will be fine.
Purge with exhaust from a idling car with a hose or water. Water can pocket and leave a bubble if you are using a torch.

[zxcvbob]

Unscrew the valve, fill the tank with water, then you can cut it with a grinder/cutoff-wheel or a sawzall.

[buck1]

I read about this a wile back. The guy said to unscrew the valve ,fill with water and cut a sizable portion off if the top with a hack saw(4 straight cuts to form a square when looking down from the top). Then hand wash it with soap and water, drain and HE SAID it could be safely cut with a torch. This is second hand info, But it sounds like it should be fine....FWIW.......Buck

[skeettx]

BE Careful
My son this year blew himself up and got badly burned doing this
He KNEW to fill the vessel with water, but NOOOO, he rinsed it, purged it and thought that would work.
NOT!!!
Remember the volitle gas is embedded in the grain structure of the metal and when it gets warn/hot from the grinding/cutting it will outgas.
Fill the vessel with water
Mike
p.s. son is ok now after life flight to burn center, and lots of pain in healing, but no lasting complications

[Suo Gan]

BE Careful
My son this year blew himself up and got badly burned doing this
He KNEW to fill the vessel with water, but NOOOO, he rinsed it, purged it and thought that would work.
NOT!!!
Remember the volitle gas is embedded in the grain structure of the metal and when it gets warn/hot from the grinding/cutting it will outgas.
Fill the vessel with water
Mike
p.s. son is ok now after life flight to burn center, and lots of pain in healing, but no lasting complications

Well that is good news. Why do we always have to learn the hard way? Glad hes alright.

[uncle joe]

you cannot get all the gas out of the tank no matter how much air you use. fill it with water then cut it, use a gfci if you plan to use a cutting wheel. to many people have been blown up cutting a gas tank.

[1hole]

"Remember the volitle gas is embedded in the grain structure of the metal and when it gets warn/hot from the grinding/cutting it will outgas.....p.s. son is ok now after life flight to burn center, and lots of pain in healing, but no lasting complications"

Glad he's okay but there is more to this story that is said. Steel is not a sponge and LP gas molecules are too large for significan amounts to embed in the grain structure to be explosive.

I like the idea of shooting a couple of holes in the top half from a distance and then filling the tank with water to insure all potentially harmful LP is forced out. It is HARD to remove one of those gas valves without the proper tools.

[Freightman]

[QUOTE Mercaptain is not a hazard.
Spill some on you and your new leather boots, your dog will not even come close to you, and you will take a shower in the back yard with "COLD" water, and you will throw away those "NEW" boots. Ask me how I know!!!!!!!!! Lemon juice is your friend!

[mdi]

I was taught (Honda Natural Gas Vehicle Training) that Mercaptin was extremely toxic. NG vehicles have fuel filters that must be changed regularily and the Mercaptin concentrates in these filters. Nitrile gloves and care with disposal of filters (Hazmat) is recommended by Honda.

[geargnasher]

I'm sure at those concentrations there would be an issue. What about respiratory protection?
My understanding is that if you can smell it, the concentrations are becoming toxic. However, I haven't suffered any ill effects from eating asparagus or cheese.

I only cut one cylinder, and I drilled a hole in it, filled with water through the hole with the valve open, drained it, filled it with CO2 from my gas welder, and zipped it open with a plasma torch. No problem except for the horrid stench.

Gear

[LeadThrower]

Mercaptans get their odor from the thiol functional group. They're similar to the alcohol functional group, but replace the oxygen in the -OH (alcohol) with sulfur to make -SH (thiol). Mercaptans are added to gas because our noses are so sensitive to them and their odor is so offensive that most people would be vomiting from the smell by the time an explosive mixture of gas and air has built up from a gas leak in an enclosed space (like your home).

They won't be present in significant quantity in an LP tank, but reasonable precautions are a good idea as thiol compounds are not good for you. Thiols are generally skin irritants. Their odor will keep you from inhaling too much of them. They are flammable, but not as flammable as propane.

[geargnasher]

Thanks for the info.

Reminds me back in college me an a few underage friends referred to the "drinking" variety of alcohol as "oh-ache-negative compounds", only the chemistry and engineering students would know what we were talking about.

Gear

[Lee W]

I filled mine with water after taking off the valve and cut it while still full. I cleaned it by melting a batch of wheel weights.
I can get a 200-220 pound batch when up to the weld joint. Make sure your heat source can take it.

http://castboolits.gunloads.com/showthread.php?t=37637

[cajun shooter]

My home propane tank had to be serviced by the owner company as you just rent the tank. They released about 15 gallons or so into the air via a 10 ft section of pvc. The top filler vave which was bad was removed. I have used propane all my life in Louisiana but had never saw it just setting in the bottom of the tank in a liquid form. It was bubbling and turning to gas but at a very slow rate. You would think that once the top was removed that the tank would be made safe but that is not so. The liquid remained in the bottom for hours. I now understand how people become hurt or killed while working with this product..

[scb]

I purged mine by removing the valve and flushing it with water. After flushing for 5 - 10 minutes I dumped about 25% of the water out. Put tank on heat and let it boil dry. I had no problem at all. Now I'm trying to figure out a way to make a bottom pour for it to take advantage of the domed bottom.

[RP]

I cut a large stand up tank one big enough for a house for a burn barrel was tired of the 55 gal drums rusting out so fast. What I did was removed valve filled with water. Then took a hole saw and drilled about 6 holes around the top of the tank for venting and a few in the bottom which are needed for air flow. Drained all the water and burned it in a fire using limbs leaves just yard brush which got rid of all the smell and any thing that may go boom. After that is when I cut the top out with a cutting wheel in my grinder the big ones are thicker. Maybe not the best way to do it but I have seen what happens when a 55 gal barrel gets a torch put to it put the guy in therapy blew the glass out of the windows across three lanes or road a small parking lot and into the building I was in at the time. It also pushed the ceiling up in the building he was in set alot of things on fire. He was the only one hurt at the time but others could have been two others that worked there was standing on the sidewalk and were knocked into the street. This was a old building and had large front plate glass windows and the ceiling was not a drop in it was old style nailed to 1/4s so it pushed alot of weight up. This dont happen all the time but one time is enough he was on the 5 barrel and was charging a guy 10 bucks each to remove the tops.