OWB Build

[hondaracer2oo4]

I currently am running a 22 year Old Hardy H4. Still going well but I know it can't live forever. I have decided to build my next OWB so when the time comes that the Hardy isn't serviceable or fixable I should be good to go. My plan is to use about 40 inches of an old 500 gallon propane tank slipped inside of a 500 gallon fuel skid tank. I plan to acquire the parts as I find them for a good deal. I am picking up tomorrow a 500 gallon propane tank. I know a few people around here have used them on their builds. I have done some reading about how others have defused the tank before cutting. I was wondering about what others have done here to get it cut. My plan right now is to fill it with water and drain it, fill it with water again and drill a 3/4 hole at the top where I want to start my cut and then cut the tank with a sawzall following some sort of straight edge that I wrap around the tank. I was leaning towards this instead of using the torches because it seems like less chances for trouble. What do you guys think? Any ideas on cutting it?

 

[RiverRocket]

A Sawzall will probably work ok...A plasma cutter would be the ticket......
Good luck...Keep us posted....Pictures...

 

[hondaracer2oo4]

I agree that a plasma cutter would work well. First problem is that I don't own one. Second thing is that I would like to cut this while it is full of water which rules out using a cutting torch. Not to many other good options unless I was to rent a K12 saw with a metal cutting blade and go that route.

 

[chaikwa]

I agree that a plasma cutter would work well. First problem is that I don't own one. Second thing is that I would like to cut this while it is full of water which rules out using a cutting torch. Not to many other good options unless I was to rent a K12 saw with a metal cutting blade and go that route.

A cutting torch should work alright if you learn how to cut with it while water tries to come out the cut you just made. Not being a wise guy here, REALLY! A torch will work under water if it needs to. I've cut tanks exactly as you're describing, filled with water. I hold the torch head at an angle so that the 'spray' it will create goes away from the head of the torch. Takes a couple of tries to determine the position, but after that it usually goes pretty well.

Another option I've heard used is to run the exhaust from a car into the tank, (with the car running obviously), so that the environment will not support combustion of any remaining propane. I've never tried this method, but it's the same principle as using nitrogen, and I HAVE used nitrogen and it works fine.

Good luck! Tell your wife or family member to let us know how it went... um... I mean, let us know how you make out!

LOL!

 

[hondaracer2oo4]

LOL, My wife will be contacting my life insurance company first before she lets you guys know how it went. I didn't think that I would be able to cut with the torch since I figured that the water would dissipate the heat to quickly to get metal up to temperature. I guess I was wrong. I think that the torch is the best option that I have then. Should I hook up a car exhaust into the top so that as the water level drops it is replaced by the car exhaust which will work to displace the o2? I think I am going to wait on cutting the tank until I get the 500 gallon fuel tank just to make sure that I cut the right length.

 

[AIM]

You don't have to do anything to a propane tank. Pull the valve off. Let it sit a day or 2 then just cut away. I've cut several of them.

 

[H-Ranch]

You don't have to do anything to a propane tank. Pull the valve off. Let it sit a day or 2 then just cut away. I've cut several of them.

The guys at the scrapyard where I got my tanks cut them with torches too. Said they've never had an issue. They did lay the torch against the tank and stood behind a few hundred tons of scrap just to get the cut started though. I would probably do that if I had to start the cut. Even after mine was cut in half it continued to smell for weeks. At that point I finished cleaning up the cut myself.

 

[brenndatomu]

Please take above suggested advise except the last one! Sorry AIM, no disrespect.
There was a tank cutting discussion on here (or hearth, don't remember which) a while back. Someone who had been cutting fuel tanks for years by washing then airing them out for a few days posted that the last one he did blew. Fortunately he didn't get badly hurt. Why risk it, take the precautions!
I used to work for a company that was BIG TIME safety oriented, we had safety meetings for 1/2 hr. every day and 1 hr. once per month. OSHA stats show that a large majority of accidents happen because someone was in a hurry or being too lazy to do it right, don't be that guy. Wash it out, air it out, water fill during the cut with the car exhaust to backfill the lost water, sounds like a pretty good plan. Just make sure the car exhaust you use isn't a carburator engine with the choke stuck on! :after_boom:

 

[hondaracer2oo4]

Thanks for the suggestions guys. Anyone have any suggestions on what to use to run from the exhaust to the tank as a hose? Once I get it cut open I was thinking about building a fire inside and heating it right up to burn off/out anything remaining in the pores of the steel etc, sound like a good plan?

 

[AIM]

Note that I said PROPANE tank. Not FUEL tank. I've never cut a fuel tank that was used for gasoline so I have no advice on that.
Propane tanks on the other hand I've cut several. The smell you get from a propane tank (even weeks after you take the valve off) is a chemical called mercaptain or however you spell it. It is something added to it to give propane it's distinctive smell. It will stay behind long after the propane gas is gone.
Mercaptain will not explode.
If it makes you feel better rinsing it out and whatnot then by all means go ahead.

 

[hondaracer2oo4]

I am actually more worried about cutting the propane tank than whatever fuel tank I get for the water jacket. Maybe my worries are irrational because of the fact about the mercaptain stinking up the propane tanks forever possibly giving you a false sense that there is still a flammable range percentage of propane left. When there really is not and the fuel tanks have no ID odor to worry you. I hope to find a fuel tank that held diesel which is usually what they are used for anyways. That should be less volatile problem if I wash it out.

 

[AIM]

I guess I forgot to mention diesel tanks. They won't explode, just burn. I don't recall ever cutting one up but I have welded on quite a few. I wouldn't be afraid to put the torch to one though.

 

[NSMaple1]

I got 2 330 gallon propane tanks this time last year. Prior to getting welding done on them, I just set them in the open for a while, oriented them so that one hole was at the bottom, another at the top (they will have holes in them already), and stuck a big funnel with shop vac hose duct taped to it in the top one, pointed sideways into the prevailing wind. That blew it out. Did that for a week or so. Tried to get a poof out of it with some flame on a long stick, but nothing. That was kind of a let down. Just remember propane sinks, so let them sit with an open hole at the lowest point.

 

[hondaracer2oo4]

Got the tank home today. A big tank to put in the back of a short bed Silverado! I got it out and its on the ground now. The guy said that he pulled the valve off yesterday to purge it and layed it on its side overnight. Really doesn't smell very much at all. I did notice though that if you stand and look level at the pipe coming from the top you see hazy vapors like you see coming from a gas can sometimes. I think I am going to fill it full of water then lay it over on its side so that it can drain and let it sit like that for a week. Here is a pic of it. View attachment 301530

Anybody have a good idea of what to use to hook up the tank to the tail pipe of my truck? Thanks

 

[dave_dj1]

shop vac hose.

 

[hondaracer2oo4]

Ok, that will work well. I have no other holes in the tank, just the one that the valves were mounted on. so to get any air flowing I believe that I will have to fill it with water and drill a hole somewhere in the top just to give the exhaust somewhere to go at first before I start cutting. Since the tank will start out being totally full of water will I need to run the vehicle for very long before I start cutting? Some people say that I should be worried about the tank filling up with unburned acetylene as I cut. Anyone have any thoughts on that?

 

[brenndatomu]

Shop vac hose may work if the truck is just idling. Could maybe melt a lil bit right at the exhaust pipe. My first thought was some flexible exhaust tubing, it maybe too expensive though, dunno.

As far as the excess acetylene, not unless you have the oxygen turned off. When you have the torch adjusted for cutting, the acetylene and oxygen are balanced and the fuel gas (acetylene) is consumed.

 

[hondaracer2oo4]

Alright, it seems like everyone agrees that once the cut is started the danger is over. Hard for me to see much danger if the tank is totally full of water when the cut is started.

 

[hondaracer2oo4]

I haven't cut into the tank yet. Waiting on getting the water jacket. Do you guys think that a 500 gallon diesel skid tank would be to thin? they are typically 12-10 gauge I think.

 

[AIM]

I think they are to thin but that is just my opinion. For me yes they are to thin. For you??? It's in the eyes of the builder.
My jacket is 3/8" thick propane tank. Likely overkill but I feel pretty good about it. My welds will rust through before anything else will.