Welding diesel tank ?

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Back in the early 60's I used to weld a lot of motorcycle & aviation gas tanks.  We would put a cap full of carbon tetrachloride in the tank (used in old type fire extinguishers) and you could weld all day on a tank if you had to.  They banned it back in the late 60's said it caused liver cancer.  Surely they've come up with something else by now?  I have a friend with a 250 gallon diesel tank (used on ranches here) wants to cut a hole in the opposite end of the filler so he can mount an electric pump. I'm not going to fill it with water. I thought about running low volume of air through it off and on for a day and then run exhaust fumes though the tank while cutting and welding.  Sure would like to hear from somebody with a better idea.
Reply:Work is typically done on tanks when they are full (less air space) with a nitrogen blanket over the area to be worked on.  When bungs are added on tanks at a gas station for instance, the tank is full of product whether it be gasoline or diesel.  The work is below ground, so the heavier inert gas stays in the area where the work is.Dry ice may work for your application to fill the tank with CO2.  Me personally, I would call someone that welds on fuel tanks.  They have the gear and can test for vapors that go boom.   A local UST contractor should have a lead on a mobile welder with the qualifications.  There are a lot of guys that do this, and a 4-hour minimum would be cheap.
Reply:I usually fill them with water and then purg the open space with argon. It's diesel, its not explosive. I would get it as empty as I could and clean it out and purge it or drop a pile of dry ice in the bottom of it and wait an hour. Plug up all the holes in it except the top and run it.  Always have an escape plan.....(Home)Miller Maxstar 152 (sold)MM211/spool gunLincoln AC 225C(Work)Dynasty 350Powcon 300STLincoln SP-175TWeldlodgic AWS150sWeldlodgic AWS300Custom Resistance seam weldersCambridge Vacuum EB weldersI smell something burning.
Reply:"It's diesel, its not explosive."Not exactly a true statement.  While diesel is not as volatile as gasoline, it certainly can produce explosive vapors when heated up.I agree with the suggestions to purge with Argon or dry ice.Back in the '70s when I worked at an IH truck shop we welded on diesel fuel tanks after emptying the tank and steam cleaning them out. Then we purged out the air by hosing Argon into the tank.
Reply:5 pounds of dry ice ..."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:If the tank has ever had gasoline in it in the past, even a small minute amount of gasoline mixed with diesel can create a dangerous and volatile flammable liquid.If you mush use a cutting torch to do this, you will have to fill the tank with an inert gas to prevent combustion of the air space. This sounds like a job for a bi-metal hole saw.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:Calculate the cubic foot volume of a 250 gallon tank.  Do the math.  Fill it with CO2.  It's cheap. Last time I calculated it, it was about 1 pound for a 55 gallon drum.  Correct me if I am wrong."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Originally Posted by Wheelman 4Back in the early 60's I used to weld a lot of motorcycle & aviation gas tanks.  We would put a cap full of carbon tetrachloride in the tank (used in old type fire extinguishers) and you could weld all day on a tank if you had to.  They banned it back in the late 60's said it caused liver cancer.  Surely they've come up with something else by now?  I have a friend with a 250 gallon diesel tank (used on ranches here) wants to cut a hole in the opposite end of the filler so he can mount an electric pump. I'm not going to fill it with water. I thought about running low volume of air through it off and on for a day and then run exhaust fumes though the tank while cutting and welding.  Sure would like to hear from somebody with a better idea.
Reply:+1 on the dry ice method.
Reply:Originally Posted by MikeGyverWelding directly on a chlorinated gas? Damn 60's you stupid.
Reply:How big of a hole?Anything under 6" I'd just top it off with CO2 & hole saw it.Buy American, or don't whine when you end up on the bread line.
Reply:First of all I want to thank everyone for thier input.   The tank has a 2" bung in the top on one end, an 1 1/2" bung in the middle of the dia. on the other end and 2- 1" bungs on the bottom on either end.  It would be hard to get dry ice in that 2" hole, so the CO2 sounds the best.  I could probably go to mexico and get carbon tetrachloride, every thing we ban here they make down there. But going down there would be like welding on the diesel tank with fumes in it   I will let you all know how I made out: I will post it under (Welded Diesel Tank)  Thank you all again.  Oh yah I'm going to drill a hole in the other end with a Hole Saw for a 2" coupling so he can put in a electric pump. I have all sizes of Hole Saws
Reply:" It would be hard to get dry ice in that 2" hole"Nope, dry ice can be broken into very small pieces by simply smacking it with a small hammer.  Of course you need to practice the same safety measures you would if you were chipping hot slag.  Eye protection and sturdy gloves, but making the dry ice fit into a 2" hole is very doable.
Reply:It doesn't look like I'll have to post under Welded Diesel Tank.   Called my welding supply who I've been dealing with for the past 20+ years.   He told me he had sold a tank of CO2 to a fellow for the same exact purpose, the tank blow up and killed him.  I've live 74 yrs by not being stupid, I'd like to see 75, thats why I asked for advise. Thank you all
Reply:If the tank blew up using CO2 for purging gas, it is because he didn't do it properly. Feel sorry for the guy. I've done 100's of diesel tank repair and it is very safe if done the right way.
Reply:I would like to read your procedure for welding a diesel tank. This tank measures 3'- 2" x 5'-0" (approximately 250 gal) #1 procedure  #2 size of bottle, small or large and how many ?Also, do I use a gage and let the CO2 flow thru the tank and out the bungs?  I had figured the guy didn't know what he was doing.  I thought with all the people on here some one had to know how to do this.    Thank you for your time in answering.
Reply:Alright, "Dry Ice" is.................CO2 in the solid state. Dry ice goes directly from the solid state to the gaseous state through a process called sublimation (bypassing the liquid transition state) at normal atmospheric pressures.CO2 in a cylinder is in the liquid state (due to the high pressure).When the delivery valve is opened, gaseous CO2 is vented out.CO2 is much heavier than air.CO2, if vented into a container under calm wind conditions, will fill the container much like if you were filler said container with water.As the container fills with CO2, air will be displaced from the container because the air "floats" on top of the heavier CO2.In purging air out of a tank with CO2, all openings in the bottom of the tank must be sealed (plugged).The top openings are left open so the air can be purged out as the CO2 displaces it.The only advantage in using compressed CO2 instead of dry ice would be that with dry ice, the clock starts running as soon as you buy the dry ice, and you must get on with the rest of the project before it disappears through sublimation.With compressed CO2 you get the luxury of a little more lee way in scheduling your work.Whether you use dry ice or compressed CO2 you still must take care not to allow stray air currents to blow across the open top bungs because that could flow in some air and spoil your purge.Laying a water soaked shop towel across the bungs will minimize air currents from aerating the tank but the towels will not interfere with the purging.If I was using compressed CO2 I would hose it in through one of the top bungs and allow enough time for the CO2 to displace all air in the tank.  You would need to calculate the volume of the tank (in cubic feet) and then know at what cubic feet/minute rate of flow the CO2 was being let into the tank.  Then just to be absolutely safe I would add about ten minutes time to the purging.Keep the flow of CO2 going into the tank until you are finished welding.
Reply:I agree in general with walkerwelds procedure, but will offer the following additional comments:Trust no one when it comes to tanks, or closed containers.  If you don't know that it's never been used or only held water, then assume it's had something flammable inside.  Assume further that whatever that flammable substance was, it's very likely to ignite or explode if heated.  When I hear customers say, " I washed it out", or "I made sure it was clean", I automatically plan on re-cleaning the tank myself or subbing the job out to a local outfit that does steam clean tanks.  Which I chose to do depends on each individual project.It should go without saying that the tank should be cleaned with hot soapy water and allowed to dry completely before any further work is done.  Professionals will steam clean tanks or pay someone else to do this.  They will also use an explosive gas meter to check that all flammable residues are gone from the tank.  Note, just because a cleaned tank reads zero on a flammable gas meter does not mean that it's safe to weld on.  Heat of welding can release flammable vapors that are trapped in seams and crevices or pores in the tank.  These can still cause an explosion or fire, unless the tank is purged of O2 before and during all hot work(welding, cutting, drilling, grinding)CO2 in dry ice form is convenient, but you have no way of knowing when enough purge time has ellapsed unless you use an explosive gas meter or O2 meter to check that the tank has been purged.  Same thing goes for using car exhaust or any of the other "more creative" solutions I've heard on this and other forums.  I dont' like welding on tanks with liquid in them, water or otherwise.  Too many issues if something goes wrong.The best way to be certain that it's safe to weld is to sample the invironment inside the tank before and during welding with an O2 meter.  If there is no oxygen inside the tank, then there is no way to start a fire.  You should check before the start of welding and periodically during welding.  These meters aren't cheap and they require regular maintenance and re-calibration.  This is why pros charge a lot of money for working on tanks; that and the consequences of making a mistake are severe, which you already know.My rule of thumb when doing any hot work on any tank that held a flammable liquid is to purge the volume of the tank 7x before starting welding.  So if the tank is 2 cubic feet, I run at least 14 cubic feet of purge gas into the tank prior to the start of welding.  If the gas flow from my meter is 15 cubic feet per hour(CFH), then I wait 1 hour before starting to weld.  If you purge at too high a flow rate, the gas inside the tank mixed with the air, rather than floating it to top and out.  Why 7X?  Assume that for each time you replace the volume of the tank you remove 50% of the original atmosphere in the tank.  Seven complete cycles reduces the atmosphere in the tank to less than 2% of the original gas mix.  since their's 20% Oxygen in air at standard temperature and pressure, a 7X purge time reduces the O2 content below below 0.5%.  Under IDEAL conditions, this should not be enough O2 to support combustion of most flammable liquids or gases.I have purged tanks with Nitrogen, although this is not as safe as using CO2 or Argon.  As mentioned before, CO2 and Argon are heavier than air and displace the air in the tank.  Nitrogen mixes with the air and dilutes out the O2, but doesn't really push the air up and out of the tank like a heavier gas would.  Again, an O2 meter is the only way to know for certain that you've diluted the O2 content inside the tank below a level that will support combustion.  Ar works just as well as CO2, but is more expensive.  Sometimes, for a small tank, it's easier for me to just use a T fitting on my Argon tank and another flow meter to purge while I weld.  This is usually faster and cheaper for me in the long run than getting a seperate CO2 tank for purge.One other issue with CO2 that you need to be aware of.  High flow rates of CO2 can cause the gas regulator/flowmeter to freeze up.  If this happens you will LOSE your purge gas flow at some point.  This is another reason I like to use Argon.  I've frozen CO2 regulators just by welding on a humid day.  I've even frosted over Nitrogen regulators on occasion.  But I can't remember ever freezing an Argon tank regulator.  I'm sure it could happen under the right conditions; so it pays to check and make sure your purge gas flow is always working.  Last thought, you cannot safely do this kind of work in a closed or confined air space.  Purging will spill a large amount of gas into the general area.  If the space does not have good air flow, you could suffocate as the purge gas and contaminants spill out of the tank and build up in the work space.  A small drop in the O2 content of the area can render anyone unconscious.  It can also snuff out pilot lights on hot water heaters and such.  So you MUST work in a space with adequate ventilation to allow the purge gas and any flammable vapors that exhaust from the tank to escape.  I realize the risks of these kinds of problems occurring are small, but the consequences are too severe to ignore those risks entirely.  Imagine doing this in your garage at home. The doors are closed because its cold or windy.  The purge gas accumulates, and renders you unconscious.   You suffocate, the pilot goes out on the hot water heater in the nearby utility closet.  Hours or days later someone comes by to check on you, opens the door, allows air and flammable vapors built up in the space to mix, turns on a light and blows everything up.  Likely to happen, no, but possible.  So work in a well ventilated space.You also need to have some plan in place to check the quality of the work or repair when it's done.  Repairs that fail and leak can be worse than the original problem.  I have no issue with sending prospective customers out to buy a new tank if I am at all uncertain that I can do the job successfully.  In fact, I've probably turned away more work on small tanks than I've done because I thought the tanks were too far gone to be safely repaired and returned to service.I will close by saying that if you aren't completely familiar with and comfortable with attempting this type of work, you should not do it.  The comments I've made here are not complete with regards to larger tanks and confined space work.  So, don't assume that you know everything you'll ever need to after having read this series of postings by me and the other forum members.Last edited by A_DAB_will_do; 03-27-2013 at 11:46 AM.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:I want to thank you both for your response. I just wanted to research this throughly.  I hope you type faster than I do or I'm going to feel bad. One of you mentioned customers coming in and telling you  'I cleaned the tank out with soap & water'. When carbon tetrachloide was still legal a fellow I went to school with came in with a motorcycle tank with a crack in the outlet going to the carb.  I told him I didn't have any carbon tet. that he needed to go and get some.  He assured me that he washed  it out with soap & water.   We also went to our sink and washed it out.  I turned the tank on it's side with the opening to the wall and proceeded to weld it.  A flame shot out about a foot long and the tank hit me in the stomach.  I was so mad I made him go down and buy some carbon tet even though I knew it wasn't going to blow again.  Later when I had my own business  a fellow came with the same type of tank and said he had washed it out.  I took the tank put it in the middle of the driveway flipped open the lid stood back threw a few wooden matches; a flame came out about a foot long and I said now I'll weld it.  The guy's eyes got as big as saucers. Tha'ts why I've stayed away from welding or welding around any type of fuel tank all these years.  I don't want to become an  .