propane tank forge

Ski

Ski

Active User
H-M Supporter Gold Member
Joined
Sep 23, 2010
Messages
280
Hello, I am going to build a propane forge and I am looking for the proper procedures to prep a propane tank for cutting the ends off. I currently have the valve removed and the tank strapped upside down. It has been outside now for a couple weeks and I was going to do a water purge prior to cutting but thought I would ask the question here first. Nothing showed up in a topic search. It is a 100 lb tank. I will be using a cutoff disk in a 4 1/2 grinder to do the cutting. Thanks ahead. Ski
 
Fill it with water before grinding or welding on it, or get some really good earplugs! You are probably OK after letting it sit upside down for a couple weeks, but who knows? You are the test pilot...
 
  • Like
Reactions: Ski
I once tried to repair a Model T gas tank. The tank had been laying outside for decades with the gas cap off. When I looked inside the tank, it was bone dry and not a hint of any gas smell. So, I went and started up my torch and when the flame touched the outside of the tank where I was going to fix it. The air inside the tank ignited and shot a huge flame out of the filler neck!!!! I had to go change my underwear on that one. And the tank puffed up and could not save it. I was just a teen when that happened. But to this day, I respect gas containers empty or not!
 
Last edited:
Purge with argon real good , I knew a guy that cut them all the time by running his car exhaust thru the tank for a half hour. With that said I made my forge from a portable air tank , no fumes
 
  • Like
Reactions: Ski
dlane said:
Purge with argon real good , I knew a guy that cut them all the time by running his car exhaust thru the tank for a half hour. With that said I made my forge from a portable air tank , no fumes
Click to expand...
I have Argon. Just picked up a second tank as a matter of fact.I also thought about buying 20 feet fuse and give it a test out in the back 40. Just to be sure!
 
If you fill it completely with warm water with an ounce or two of detergent added, you will flush essentially all remaining volatile propane. Propane has ethyl mercaptan added to give it the stink and it will settle out as an oily liquid which can have some propane dissolved in it. When cutting a tank with a torch, the oxygen introduced when the tank is pierced can cause a flare up or possibly even a small explosion from this oil.
If you are concerned, you can fill the tank with water when you are cutting with the grinder. It will be messy but the chance of a fire will be virtually nil.
 
  • Like
Reactions: Ski
I've used the fill with water method a couple of times and I'm still here. Shake a bit every time I touch the grinder to the tank though. I read somewhere that a little bleach in the rinse water will help neutralize the ethyl mercaptan. I tried it and it seamed to. I repurposed one as a hydraulic tank, it took a lot of super clean to dissolve the oily residue.

Greg
 
I'm not sure that this is much safer, but I saw an old blacksmith do it in the following manner. He heated a piece of coil spring to forging temperature and made a hack tool out of it. That is a wedge with a tapered shank wrapped as a handle so as not to transmit vibration. It was air quenched and tempered to straw. When struck on the broad part of the wedge, it will slice right through sheet steel. This may spark, but a lot of blacksmiths do not think that tempered steel draws many sparks. I once participated in a charcoal retort building workshop where there was no power, and this was much preferred to using a torch or a hacksaw.
 
The guy that cuts a lot of them ( 5gal to 200 gal ) told me the most important thing is to get all the oxygen out . He used a plasma cutter , I would make BBQ's out of them after he made a couple cuts on them , I wasn't that brave
 
  • Like
Reactions: Ski
You must log in or register to reply here.
Back
Top