Thread: Petrol tank

Hello everyone

I'm after some advice about a small project I'd like to complete, please. I needed a new letterbox and my wife wanted something different than what you'd typically pick up in a hardware store. I bought a nice old petrol tank on ebay with the idea of converting it into a letterbox. I've attached some photos.

What do you think would be the best way to neatly cut the slot in one end, and also the entire other end so that it can open on hinges? Also, I don't want anyone scratching themselves, so should I crimp something along the exposed edges? I was thinking lead. Any ideas? I just want to maintain the look of the tank.

Thanks in advance for any advice / suggestions.

Regards

Paul

Firstly welcome to the forum.

Next given it's a petrol tank, even a very old one, I would say any form of opening has to be done VERY CAREFULLY.

First find out all about the safe way of opening up a petrol tank and that will largely determine how you do it.

Originally Posted by gooddroprob

Hello everyone

I'm after some advice about a small project I'd like to complete, please. I needed a new letterbox and my wife wanted something different than what you'd typically pick up in a hardware store. I bought a nice old petrol tank on ebay with the idea of converting it into a letterbox. I've attached some photos.

What do you think would be the best way to neatly cut the slot in one end, and also the entire other end so that it can open on hinges? Also, I don't want anyone scratching themselves, so should I crimp something along the exposed edges? I was thinking lead. Any ideas? I just want to maintain the look of the tank.
l

Originally Posted by gooddroprob

Hello everyone

I'm after some advice about a small project I'd like to complete, please. I needed a new letterbox and my wife wanted something different than what you'd typically pick up in a hardware store. I bought a nice old petrol tank on ebay with the idea of converting it into a letterbox. I've attached some photos.

What do you think would be the best way to neatly cut the slot in one end, and also the entire other end so that it can open on hinges? Also, I don't want anyone scratching themselves, so should I crimp something along the exposed edges? I was thinking lead. Any ideas? I just want to maintain the look of the tank.

Thanks in advance for any advice / suggestions.

Regards

Paul

Hi Paul, first thing to do, would be to get the tank degassed, ideally professionally, even though no fuel may have been in there for some time, fuel vapour can remain for quite a few years DAMHIKT. On the end with the filler, cut a horizontal slot with 2 verticals about 20-25 mm high on the ends and bend this out to form a "verandah" over the opening, a jigsaw will do this OK. The other end, cut inside the edge again with a jigsaw and pop rivet on a 50 mm hinge on the straight edge, use the lump as a handle, to be able to get the bills out
Kryn

I watched a CIG rep pull a tank out of a car, empty the petrol and give it a flush with water and then after flushing and filling it with argon welded the thing up. I moved a long way away and wondered if I would ever have the courage to do the same thing. We then put the tank back in and went racing.

Take all precautions before cutting it open.

That works OK as flushing it with water removes any liquid fuel and filling it with argon being a non-combustible gas neutralises any vapour. Exhaust fumes plumbed into the tank neutralises vapours also needs to be done for quite some time though.
I've had 2 tanks explode on me after welding several times in the same spot. Change Jocks time, I refuse to do another one, third time unlucky.
Kryn

It works but he gets worker's comp if it doesn't and I would get a pile of medical bills and a lot of pain if it didn't work by some remote chance.

Thanks for the advice guys, particularly in regard to safety. I'll go ahead and use a jigsaw, after getting the tank properly flushed.

Cheers

Paul

If you have access to dry ice throw some in the tank. The CO2 gas formed is noncombustable.

Originally Posted by gooddroprob

Hello everyone

I'm after some advice about a small project I'd like to complete, please. I needed a new letterbox and my wife wanted something different than what you'd typically pick up in a hardware store. I bought a nice old petrol tank on ebay with the idea of converting it into a letterbox. I've attached some photos.

What do you think would be the best way to neatly cut the slot in one end, and also the entire other end so that it can open on hinges? Also, I don't want anyone scratching themselves, so should I crimp something along the exposed edges? I was thinking lead. Any ideas? I just want to maintain the look of the tank.

Thanks in advance for any advice / suggestions.

Regards

Paul

advice

do not use an angle grinder to cut into the tank
do not use any form of heat torch (Oxy acetylene, propane, etc) to cut into the tank -- I too have seen the results of a petrol drum explosion
do not use a power saw to cut into the tank

the safest way is to use a hammer and cold chisel.
once the cut is started, the metal might be thin enough that you can finish the cutting with a pair of hand shears or a nibbler.

You will notice a common theme among all the advice given here.
Do not do/use anything that creates heat/sparks/friction until such time as the tank is de-gassed. That means, no grinders, hole saws, hacksaws etc.
In a previous workplace we worked on many fuel tanks, both diesel and petrol and our standard method of attack was to take the steam pressure cleaner, wire the trigger on and place it in the tank with all openings blocked except the one with the steam cleaner lance in it, which obviously would be on top. we then ran the steam cleaner for 30-60 minutes depending on the size of tank, emptied the hot water out of the now very hot tank, gave it a good sniff and if it smelled sweet enough, we proceeded to work on the tank while still hot. A cold tank may appear gas free, but when heat is applied from welding, cutting or even the full heat of the sun, vapours will leach out of the pores of the steel/aluminium.
I am not a big fan of filling with water or exhaust fumes. If filling with water, you can easily concentrate the explosive vapours into high point of the tank that is just waiting for an ignition source and exhaust fumes are a totally unknown composition which may have flammable components remaining. Admittedly a much larger version of your tank, but there were two workers killed while fitting gas and level sensors to a waste oil tank not far from where I worked. They had filled the tank with water, believing they were safe, but the tank had a slightly pitched roof and all they had done was to concentrate the fumes so that when the angle grinder penetrated the roof they both did their best rocket man impressions and were launched skywards. The landing was not so kind. The grinder in question was foun on a roof nearly 200M away. Likewise, there is no guarantee that solely purging with argon/nitrogen or CO2 will fill all areas and displace the explosive vapours. I have worked on professionally purged road going fuel tankers and they had gotten the tank hot enough to blister the paint as part of their certified purging process.
I see no reason, given the small size of the tank that you couldn't fill with water and a little detergent and actually boil the tank on a fire or the barbie for half an hour or so. Just remember to work on it while it's hot and give it a good sniff first.
No letterbox is worth dying for, so proceed with great caution and if in the slightest doubt, don't do it.

When I made my gas powered forge I used an old rusty propane gas cylinder from a fork lift.

I removed the valve and filled it with boiling water and detergent once a day for 7 days. Then I cut into it with an angle grinder and it still gave me a brief WOOF! and a small blue flame shot out of the cut and I nearly had to change my daks!

I posted this on I Forge Iron and it was explained to me that it was most likely the mercaptan oil (the stuff that gives the gas its smell) that they add to gas that had condensed into the pores of the metal and the heat had brought it out and ignited it.

Thanks Karl, I had forgotten about using HOT water in a tank, it's been about 20 years since I'd last done a tank, forgetting something like that may not have been healthy.
Kryn

That was an excellent post Karl.

Phil

Just wondering if filling it with sand would work? It's a small tank. Or chain drilling?

I've seen blokes fill tanks with water (may of been hot but not sure) and it worked ok. I've also seen a bloke cut into a 44 gallon drum with a angle grinder and it went off (he had "purged it" before he started but obviously not enough).

Ben

Years ago, I used to drive a fuel tanker so I’d endorse Karl’s advice above. The tanker was always thoroughly steam cleaned before welding or other work was carried out because the metal pores used to absorb the fuel vapour (and hence explosive). Later when the steamed out tanker was refilled with fuel, we had to follow a process called “flash loading” which involved initially filling at a slow rate until the metal pores were re-saturated with petroleum vapour, otherwise a possible risk of explosion.