On my ‘32 I have a stock repro tank from Vintique. Before paint I had it on the road for a little after mock up and the small brazing on the side brackets broke off which seems to be common on them. I would really like to tig weld them back, the gas is drained of course but was going to fill with water to displace all the gasoline fumes. Would the water in the tank make it a big heat sink and harder to weld. Does this sound like a good plan? It is a stock unaltered frame with original rear spreader so I don’t think the frame being out of whack made it break but those little tacks from Vintique seem inadequate. Thanks in advance.
If your going the water route, rinse it out several times before welding. If you have time let it set open as long as possible. Then fill it almost to the top, but leave a little room for air, rot state your tank to weld on top, should weld fine with no problems. Don’t put the cap on, use duct tape or plastic sacks with rubber bands. That how I always welded on fuel tanks and I’m still here, jmho . Bones
Fill the tank with a gallon of bleach mixed in the water, let it set overnight. Rinse it out with water, and let it dry, then it is safe to weld. That's how I have been repairing tanks for years.
This is just my two cents and speaking from a personal experience that I seen first hand. I was watching a guy do a gas tank off a custom Harley. It had a small pin hole towards the back of the tank. He rinsed it out a few times with water, then filled it with water and proceeded to weld it. About five seconds after the arc struck, the tank went boom. Luckily he was not hurt, just had a ringing in his ears for a couple days. I believe what had happened was there was still a void that did not fill all the way with water and was a place for fumes to accumulate. When the spark found that small pocket of gas vapor it ignited. The water could not be compressed and opened that tank up like there was a bomb that went off in it. Over the years I have welded on dozens of fuel tanks and have not had one bad incident. I rinse the tank out multiple times with Simple Green or a citrus based cleaner. Make sure the tank is left open, gas cap, sending unit pulled out, etc. Like I said this is just my two cents, but please be careful and live to rod another day.
Years ago I heard of running a hose from a running car's exhaust into the tank to evacuate the gas fumes before welding. Anyone ever hear of that or tried it?
I would also recommend leaving an air hose attached for about an hour to make sure you purge the tank of fumes. As satin recommends, an Argon or CO2 fill while you are welding won't hurt.
I use the car exhaust but I hot tank the gas tank before. But before I had the hot tank I cleaned them well with soap and water and used car exhaust for at least 5 minutes.
When I was in the heavy equipment & truck repair business, filling a fuel tank with exhaust fumes was the standard practice before welding on them. That is the practice used in shops all around the country.
The idea is to displace the air (oxygen) out of the tank, so the remaining fuel vapour (that's very hard to get rid of) can not burn/explode. It can be done in many ways, basically with any gas that does not contain free oxygen - such as CO2, argon, other MIG/MAG/TIG welding gases (not O/A welding gases for obvious reasons) or exhausts from a gasolene engine (but not a diesel!). The method to fill with water is also effective as you KNOW there is no oxygen left where the water is, but there's still an air pocket above the water where you weld. Combining water with an inert gas should work well (and not require a huge amount of gas thanks to the smaller volume to fill), a simple method to produce CO2 might be adding baking soda to the water - that's what the bubbles you get are.
On a stock '32 the tank was not mounted solidly on both sides. The stock frame twisted and moved. Boxed frames are stiffer & most bolt them down. Get on the FordBarn & see how the stockers were mounted with springs on one side.
I have welded more than 30 gas tanks. Rinsing with water is good. Dont leave it full of water. Wheres that water going to expand to? Exhaust gas is good. After you think its rinsed, leave all holes open and 'burp' the tank by passing a open flame over the gas tank filler opening. You get a soft safe 'whoosh!' and you know there is nothing left to burn
I wouldn't even work on the tank unless I was purging it with an inert gas or a hose to a exhaust pipe. Even prepping the tank and grinding the brass off the side could possibly create a hole in the tank and cause a explosion. I've welded on tanks and pipes with liquids in them without a problem but nothing as thin wall as sheetmetal. I would fill a quart can with water and try to TIG weld on it before I tried to weld on a 32 tank if you go with that method.
A few pound of dry ice tossed inside the tank before cutting or welding is detailed in Petroleum Equipment Industry underground storage tank guidelines. Sorry, I’ve been out from the industry for more than twenty years, so do not have specific numbers to use. The evaporating CO2 displaces all the oxygen/air and eliminates the explosion hazard. I tried filling a gas tank with water before welding, back in the sixties. Water was a terrible heat sink when I first tried and tank was water filled as full as possible. Emptied a bit of water and the tank fumes gave me a healthy burp on the second attempt but tank did not actually explode, so I continued/finished the work. Scary enough to not be willing to try it again.
I usually let the tank sit outside in the weather for a few years. When I get around to it, the gas fumes are usually gone.
I did the tank on my '37 and I removed the tank flushed out with water then I mixed water and apple cider vinegar 50/50, let it set a couple days sloshing it back and forth now and then. Removed all mixture after a couple days and welded it no problem. I then dried it and sloshed with diesel to make sure no leaks and keep from rusting. Worked for me
I would think that car exhaust would have enough unburned fuel vapor to cause problems. Anyhow, I've always run a rubber hose on a T from my mig welder's CO2 tank. CO2 is heavier than air and I try to keep the tank sloped so that it "fills" with CO2 that displaces the outside air. I always wear ear plugs in case something goes wrong.
Dry Ice is my answer , welded on many Liquid Propane pipelines , Natural Gas pipelines , in the past using this tried and true approach . Just allow an opening for the vaporizing CO2 to escape . It’s all about the LEL /UEL of the fuel as in mixture . It has to be with in the explosive mixture of the fuel or the devil can’t make it burn . Waving a flame over the escaping opening is about the easiest way to determine if you have reached a safe level to weld . You may want to invest in a bundle of “adult depends” before starting this adventure . Sometimes if it question about safety , take it to a pro, drop it off and pick it up when repaired is the safest way to the finish line . Nothing is worth more saving than your life or a loved ones life . $$ can fix anything safely , just be safe and be sure you understand the properties of fuel , fumes are heavier than air they will be in the lowest spot of the tank and on the floor or ground where you are working . Don’t be a fool and smoke while you taking a brake allowing the venting process to take place . I have seen pipeline welding trucks with the doors blown off , from the the thinking “ I’m in the truck , it’s safe to smoke in here ! “ it only takes striking the match to be included in this type of mistake , and you may not be able to say “ damn I shouldn’t done that “ ! Just be safe , to enjoy the hobby for years to come .
I welded up a filler neck onto an old 5 gallon air tank to use as a gas tank for an old Jeep I had one time. Something hit it and broke it loose a bit from the tank, so I took it out of the Jeep, washed it out several times with soap and water, then filled it almost to the top with water before I started welding on it. Let my hood down, struck the first arc, then WHOOSH! Jerked the hood up to see the filler neck flaming a foot high ! About scared the crap outta me! I ran and got behind a vehicle and watched the flame burn for about 30 seconds then slowly die down. After waiting a few more minutes for my heart rate to slow back down, I went back over to check it, the fire was out. Settled down enough to weld the neck back on, no more flames. I think there had been just enough fumes left in the very top of the tank to ignite, and by the neck being open, that was the escape point. I haven't welded on a gas tank since then!
I second this. Always test it with a match before I start welding; at least then you're expecting it. Mike
Fill with Argon or Helium, you will get a better weld. And no black junk on the backside of the weld . IE inside the tank .
The one thing I could add is the use of silicon bronze rod with the tig, Less heat involved, thin material and welding it could be prone to cracking later on
I have no experience on this, but read this somewhere: first drain the gas tank, then pour in 2 litres ( 2 quarts) pure alcohol (ethanol), shake the tank, drain alcohol out. Pour in water half gallon, shake the tank and then drain dry. Theory in this: gas residue dissolves 100% to alcohol and alcohol residue dissolves 100% to water so there is no flammable left after that procedure...
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