welding diesel tank

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Never had to do this before, I have done gas tanks but wondered about proper cleaning and risks of diesel tanks ?  I have to cut the end off (plasma) then weld a flat plate on.                             thanksDan.Repair Specialties LLC
Reply:I'd just let it air out good.  It's not nearly as dangerous as a gas tank.  I've tigged an aluminum tank off of a semi with no problem.DewayneDixieland WeldingMM350PLincoln 100Some torchesOther misc. tools
Reply:http://www.labour.gov.on.ca/english/hs/alerts/i12.htmlhttp://ncsp.tamu.edu/reports/CCOHS/record2493.htmAre you sure there was never a trace of gasoline in any of the diesel ever put in that tank?Just don't do it.
Reply:You will definitly get both sides on this subject.  Some say yes and some say no.  But you said you've done gas tanks before so diesel shouldn't be a problem for ya.DewayneDixieland WeldingMM350PLincoln 100Some torchesOther misc. tools
Reply:We all appreciate that you gave the general location of where you are.  In this case I am relieved to say I am in a safe area.   All tanks that have contained any sort of petroleum product should be steamed out and then vapour checked with a detector.  At the very least fill it with water up to the last inch that you are cutting.
Reply:PLEASE JUST DON'T DO IT ON A WHIM BECAUSE THE LAST ONE WORKED FINE. Tanks are like girls no two are the same. I work in an oil refinery and do this work daily. You got to make sure there is NO LEL inside FIRST before you strike an arc with a meter or your life, pick one. Steam is the best way to remove LEL. Soap does a good job but watch where you dump the sludge because its hazzardous to other living things also. Then check it with a meter. Nitrogen can be added to purge also but it will kill you also if used in a confined space. So please be carefull...BobBob WrightSalem, Ohio  Birthplace of the Silver & Deming Drillhttp://groups.yahoo.com/group/southbend10k/http://groups.yahoo.com/group/sawking/1999 Miller MM185 w/ Miller 185 Spoolmate spoolgun
Reply:You all know my take on this subject..  ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I have welded cracks in diesel tanks with diesel flowing out of the crack. I just hit it a couple of times with a chipping hammer to slow the flow and started welding it with a 7018. Sealed right up no problem. Had some flames of course but no explosion. I would say just make sure the cap is off so it can swell and bust.
Reply:Bob WrightSalem, Ohio  Birthplace of the Silver & Deming Drillhttp://groups.yahoo.com/group/southbend10k/http://groups.yahoo.com/group/sawking/1999 Miller MM185 w/ Miller 185 Spoolmate spoolgun
Reply:I knew a guy personally that was cutting the top off a drum that had motor oil in it.  It blew up, burned him bad and burned his garage down.  Its only motor oil right?DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:laugh if you want. It can and has been done.
Reply:Well I guess this is one situation that I will never see the results before my very eyes..'Cause I aint going anywhere near that IDIOTIC move..IMHO.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:if there is no oxy present the diesel can't ignite.  also you have to get the tank up to diesels vapor point before it can ignite.  cutting the top off a tank and welding a crack shut are very different things.
Reply:Me no care.. Stranger things have happened.. They seem to go up no problem whan something goes wrong on the highway..Welding a fuel tank full of fuel?I dont care whats in there......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I've welded several desiel tanks!1)First we flush with fresh water.2)Drain Tank.3)Purge tank with inert gas.4)check LEL/Oxygen levels.5)weld or cut and monitor.6)complete work.The one thing I will not weld is a gas tank taboo!
Reply:Originally Posted by WVWelderlaugh if you want. It can and has been done.
Reply:WVWelder the only reason the tank didn't blow up was because you were more than likely welding below the area where the vapors would be(as you stated the fuel was running out). I'm sure alot of welders have done this but the thing to remember here is not all forum members are up to speed on welding and could get hurt by thinking it is ok to weld a tank that way, so we need to be careful not to encourage them to take chances. There are safer ways to deal with tank welding.
Reply:Used to ride the headache ball, wash off with benzene and build boilers with no fall protection either.  Of course, not every one survived so we changed the way we do things.  INERT!Mark WebbSafety Engineer  Bobcat 250Hobart Handler 140My welds look best capped with a grinder,but they hold.
Reply:I did get the tank dropped today, of course they said it was cleaned and they even ran a saw cut through it--yikes !  the thing still had fuel vapor and sludge in it. None the less I am going to treat it like I have gas tanks in the past and do it right. Normally I would stay away from these jobs , but its for a pull tractor, and in my area a guy gets a lot of cash fab jobs down the road when you take care of these guys on their less appealing jobs.       thanks for all the feed back. like some people said- this in not a job for a novice, any tank should be treated like a bomb ready to go off-because they are !Dan.Repair Specialties LLC
Reply:I'm in no way suggesting this, but my old boss used to run diesel exhaust into gas tanks while welding on them. Anyone ever hear of the technique?
Reply:Yes, Gus_Mahn, inert gas from engine exhaust is used to blanket the oil holds of supertankers at all times.  I had a job once to analyze why the 10" roller bearings of the huge inert gas fans of a Chevron supertanker were failing prematurely.  While we were standing by watching the shore contractor install new fan bearings preparatory to a shakedown cruise during which we would measure bearing vibration, I observed the contractors filing down the thickness of the bearing shims directly above the new, open, unshielded bearings lying on a dirty rag on the deck.  The filings were falling directly into the brand new, unwrapped, open bearings.  Since it was already too late to save those bearings (in the shipboard environment), I called the ships chief engineer over and pointed to what was happening.  He was bewildered and did not understand what I was pointing at.  These are the guys running supertankers into our ports and up to Alaska.  These fans drew gas from the exhaust stack of the gas turbines and sent it into the space above the cargo.ANYWAY, engine exhaust gas is used as inert gas to prevent explosion of petroleum vapors in ship holds and should do the same job for a tank being welded.  The problem is quality control.  The ships have continuous monitoring of the oxygen content of the vapors blanketing the petroleum in the holds.  The small shop welder is probably not equipped to perform such thorough, continuous monitoring. If I was tackling this task, I would have a continuous flow of inert gas like nitrogen, carbon dioxide, or engine exhaust through the tank with a rubber flap or other device to insure that inert gas could only flow out the exhaust port and preventing atmospheric oxygen from entering the tank.  This would be after the tank was completely steam cleaned, filled with water to minimize gas volume in the tank, and continuously purged with a constant flow of inert gas.  The rubber flap must not create a tight seal that could result in pressurizing the tank above a pressure that you can easily hold with your hand over the fuel filling port (NOT over the small fuel tube port to the engine).  Inadvertently pressurizing the tank above a fraction of a PSI (before you cut into the tank) creates a whole new bursting hazard.There have been plenty of dramatic deaths and buildings destroyed by welders thoroughly cleaning and purging a tank, then starting to weld or cut on the tank with the ports open, allowing the entry of atmospheric oxygen.  The fact that someone has done it that way before once or many times and survived is absolutely no reason to risk your life to do it that way.  In fact, I would risk the wrath of many experienced welders by stating that it is idiotic to do it that way.  You are not going to have time to say, "holy s---, this thing is going to blow," and get away.The hazard is that residual petroleum in the tank will be vaporized by welding/cutting heat and mix with air in the tank, forming an explosive mix.  Each petroleum product has a fairly narrow range of mixes with air that is explosive.  If you hit that mix and provide an ignition source, you are gone.  If you have air and petroleum vapor present, but not in the explosive range, it will not ignite, even if the mix has an excess of fuel vapor in air.  As I recall, gasoline has one of the broadest ranges of mixes with air that is explosive, which is probably why it is a very versatile fuel.   Some of the guys that got away with casual purging methods simply did not hit the explosive mix.  This is definitely the reason that, for example, welding on a leaking tank below the fuel level is unlikely to lead to an explosion (although you could have a pretty dramatic fire).Remember that using up a full bottle of nitrogen or carbon dioxide to purge the tank while doing the job is dirt cheap compared with the cost of a funeral. awrightLast edited by awright; 05-18-2007 at 02:15 AM.