welding a big fuel tank

admin

Hey guys, i have to weld on a 500 gallon diesle tank that was shot last night with a rifle. I weld on these tanks every once in awhile, but this one just doesn't feel right. I put 20 lb of dry ice in the tank and let it sit for an hour. When i checked it with my o2 meter, it was still at 15%. I don't like to weld anything above 7%. I have never had to put plugs in before, but with a windy day like today, was i losing my co2?? I am going to try to weld this tomorow. I am going to try to put dry ice in again and plug up one bun hole and see if i can get that O2 % below 7%. Any ideas from guys who weld on fuel tanks???
Reply:Originally Posted by Ag SpecialtiesHey guys, i have to weld on a 500 gallon diesle tank that was shot last night with a rifle. I weld on these tanks every once in awhile, but this one just doesn't feel right. I put 20 lb of dry ice in the tank and let it sit for an hour. When i checked it with my o2 meter, it was still at 15%. I don't like to weld anything above 7%. I have never had to put plugs in before, but with a windy day like today, was i losing my co2?? I am going to try to weld this tomorow. I am going to try to put dry ice in again and plug up one bun hole and see if i can get that O2 % below 7%. Any ideas from guys who weld on fuel tanks???
Reply:Why even go to all that trouble. NO RISK - VERY LOW EXPENSE.Just drill the hole and tap and thread and put in a bolt.Even if the tank is only 3/16 inch thick it will work. I have done it.Or for a larger hole get a circle and put holes every 2 inches around the outside edge.Marl the holes on the tank drill and tap and bolt on the cover with a gasket.I hope this gets to you in time.
Reply:Or just weld it, it's a diesel tank   I've done several steel diesel tanks lately that still had diesel in them, no problems.DewayneDixieland WeldingMM350PLincoln 100Some torchesOther misc. tools
Reply:Lincoln "tombstone" welder?Kind of ominous.Diesel does have a higher slash point but it still can ignite.When you weld heat builds up and pressure can build andthen you have a potential bomb.Please be careful.
Reply:ive welded on empty ones with no problem, but i have also cut a few open with my plasma cutter with fuel still inside and it seemed to be ok..-NateMiller Trailblazer 302gMiller Spoolmatic 30aLN-25 x 2Idealarc SP200Hypertherm Powermax 600
Reply:Dave can you give me an idea of how much argon it takes to purge a 500 gallon tank. Do you just tape of the hose in the buns and tape the other bun with tape with a small hole and turn on the argon with a flow meter. How do you purge saftey and how much argon do i need??
Reply:I think the dry ice method is better and cheaper. CO2 is effective not only by removing the oxygen and by cooling the system while the dry ice sublimes, but the molecule itself is, by reacting with free radicals, effective in stopping the flame propagation. Here it would also, due to its greater density, tend to stay in the tank if all the openings are near the top. The openings other than the hole being welded can be covered with tape, or rags even can be stuffed in.I would use more care if the tank were for acetone or some other such chemical but for diesel, I don't think checking for residual vapors or any precaution  beyond the dry ice is needed.
Reply:Put a temporary or permanent "plug" on the outside of the tank hole. Tape a coffee can or similar on the back side (inside of tank) with duck tape, fill it from the top (or the other side) with your favorite flavor of purge gas. Weld on the OUTSIDE of the tank. We use "speed tape" all the time for our SS cylinders, tubes and the purging of the air. You're gonna need alot of Argon, nitrogen, etc. to purge a 500 gallon tank...try my method.  Easy button > OJohn -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:I weld on these almost 2 a month from 500 to 5000 gallon , I generaly empty them steam clean them for a couple of hours , then fill them with water , I prefer a wire feed because  heat spread is slower than stick, and if I dont feel safe about it and its a rush to get it done , then as it was mentioned earlyer drill tap and bolt or patch plate ,
Reply:P.S   co2 is the only way to go for petrolium vapors
Reply:Originally Posted by Ag SpecialtiesDave can you give me an idea of how much argon it takes to purge a 500 gallon tank. Do you just tape of the hose in the buns and tape the other bun with tape with a small hole and turn on the argon with a flow meter. How do you purge saftey and how much argon do i need??
Reply:Originally Posted by littlefuzzOr just weld it, it's a diesel tank   I've done several steel diesel tanks lately that still had diesel in them, no problems.
Reply:It was repair of a bullet hole in the tank.I would drill and tap and put in a bolt.That is what i would do.Use 3M 599 ultra grey sealent made for wet diesel.Like others have said, welding on a tank that had a petroleum product is risky.Even if it was steam cleaned. There are many kinds of tanks and different baffle systems etc. it is hard to know what is inside sometimes.What i do know is how many times I have read about welders being killed. Even when they were told is was ok. But the part I do remember is that those that died were welding on a tank.
Reply:Without an explosion meter i would not even touch it no matter how good you thought you cleaned it. But thats just me. We do tanks up to a couple million gallons...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:Picked at random from a LIST of fatal accidents on the internet,A Hispanic Welder Died when the Diesel Fuel Tank He was Welding ExplodedCalifornia Case Report SummaryA 25-year-old Hispanic welder died from injuries received from an explosion of a diesel fuel tank he was welding. The victim had just struck an arc with the welding torch (MIG FCAW) when the explosion occurred. He was making a repair to a diesel tank mounted on the bed of a pick-up truck. The diesel tank still had fuel in it. (one cup) The victim did not correctly purge or ventilate the fuel tank before beginning to weld. The company had no documented safety or training programs available for the employees to follow. The CA/FACE investigator determined that, in order to prevent future occurrences, an employer should:*Develop, implement, and enforce procedures for welding on fuel tanks.*Establish and maintain an Injury and Illness Prevention Program (IIPP) in language(s) employees can comprehend.*Establish and maintain training and testing programs that verify and document an employee’s achievement of skills.IntroductionOn May 19, 2007, at approximately 11:00 a.m., a 25-year-old Hispanic welder died from an explosion of a fuel tank on which he was welding. The CA/FACE investigator learned of this incident on May 22, 2007, from the Los Angeles Department of Coroner’s post mortem reports. Contact with the victim’s employer was made on June 12, 2007. On June 14, 2007, the CA/FACE investigator and a Spanish language interpreter traveled to the company that employed the victim and interviewed the company owner and other employees in the shop. Photographs of the incident scene were taken. The employer of the victim was a welding and repair shop for heavy duty trucks. The company had been in business for over 24 years, 13 of those years at the site of the incident. The employer of the victim employed four people. The victim had worked for the company for 16 months.The victim was born in Honduras and had been in the United States for three years. He had an eighth grade education and did not speak English. It is unknown if he had any welding experience previous to this job. The company did not have a safety program or an IIPP. The company did not have a training program that provided safety training to employees in the language spoken by the employees. The company’s owner was born in Mexico and learned welding through on-the-job training (OJT) from his father. Employees of the company were trained in welding by the owner and there was no other formal training/testing program.Back to TopInvestigationThe site of the incident was a service bay in a welding and repair shop for heavy duty trucks. On the day of the incident the victim was assigned the job of locating a leak in a diesel fuel tank mounted on the bed of a customer’s pick-up truck. Once the leak was located, the victim was supposed to weld the spot using a welder referred to as a MIG/Flux Welder. According to the owner, the customer told him that the tank was used for carrying diesel. Neither the owner nor the victim verified the contents of the tank. According to the police report, the tank had less than one cup of fuel in it. The victim did not purge and ventilate the fuel tank before beginning to weld. When the victim struck an arc with the welder on the tank, it exploded. The victim was thrown approximately ten feet and he landed on the shop floor. Coworkers in the shop area who heard the explosion rushed to the victim’s aid and immediately called 911. The paramedics and fire department arrived within minutes and treated the victim, then transported him to a local hospital where he died from his injuries.Right above this story was a story of a welder who died in an explosion of a wasteWATER tank that he was welding.Last edited by Donald Branscom; 06-28-2008 at 04:46 PM.
Reply:Good article Don...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:Not sure if this will be any help or not, and I dont know how technical you want to get with it, but when I was working at a local shipyard we routinely had to weld on 10,000 gallon diesel tanks. A marine chemist would come out and sniff the tank so to speak( some type of air moniter) and that would determine how much gas he would use to inert the tank. Im not sure what he used to inert the tank, maybe Co2 like OldIron was talking about. We never had any types of problems when using this method. That being said though, the tug boat tanks were already equiped with a 1/2" coupling welded through the deck to perform the inerting. Not sure if you would be able to outfit your fill hole with something to be able to inert tank. I know this is a little overkill but maybe it will give you a few ideas.
Reply:Here are a few more stories. I work in a refinery and we get to watch movies of tank fires in fire training class, not a good thing to see...Bobhttp://ncsp.tamu.edu/reports/MSHA/msha1.htmhttp://www.cdc.gov/niosh/fire/reports/face200025.htmlhttp://www.ukwelder.com/forum/index....97&#entry53297Bob 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:in my younger days i ran a steam cleaning truck for oil feild tanks and tubing. if you are going to do any weldingthe tank i would highly suggest having it steamed first. the cost of having somebody come out to steam it makes a 500 gal tank about the smallest tank that would be worth it. when i say steam it that is not to be confused with a hot water or wet steam power washer. there is a big difference. also when i steamed tank for welding repair we would go by a combustable gas detector rather than a O2 meter to judge the job. unless there happens too a steam cleaning service near by that you can take the tank to i'm in group of guys that would repair it with a patch and sealer.
Reply:Fill it up with water (that's how we patch crude oil storage tanks), or hook your exhaust to it and let it run until the tank gets hot, as in will almost burn your hand, then you are ok just leave the exhaust running while you weld it up - works for gas tanks as well. If you are in the oilfield hook a hot oiler up to it and steam for 4 hours then check with an explosion meter. If it shows safe turn the steam back on and weld it up. That's the way we do heater treaters and there aren't many things more subject to going boom than those things. Never trust an oxygen meter for anything except making sure there is enough O2 for you to breath. Oxygen levels will change with the slightest breeze. Always use an explosion meter (AKA a sniffer) if you don't want it to go boom. Always check it with a butane lighter and never ever use acetylene because it burns out the sensor.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Regarding the dry ice: [Corrected calculations!]The atomic weight of CO2 is 44 ; 20 pounds of dry ice / 2.2 lb per Kg = 9.1 Kg of dry ice.Then 9,100 grams / 44 grams per mole = 207 moles.Since one mole of gas occupies 22.4 liters at STP roughly, and one gallon ~ 4 liters, then207 moles x 22.4 L/mole x 1 gal/4 L = 1160 gallons of CO2 vaporThis is 2.3 times the volume of a 500 gallon tank. If the main openings are closed with tape or rags while welding to prevent diffusion of gases in or out and a small amount of dry ice remains while welding, the newly sublimed CO2 will be escaping from the weld area to some degree, and will carry away any fumes released from the heated areas nearby. No oxygen will be present to combine with them, they will be extremely dilute, and no reaction can occur.Recall that I earlier said that the top should be where the gases escape while the bulk of the dry ice is 'melting' because the CO2 will tend to stay at the bottom of the tank so the air will rise above it and be able to leave through those holes. A loose rag will allow this while slowing diffusion, as mentioned above.Do not put dry ice in a sealed tank; the pressure of liquid CO2 is something above 600 psi, which would be distructive to most tanks.Last edited by David R; 07-03-2008 at 06:08 AM.
Reply:Conversion table for CO2:http://www.uigi.com/co2_conv.html
Reply:well 500 gallon tank , one bullet hole , drill tap and put in a bolt , it would be the safest, with out heat ,or ignition source, one other factor its faster, mr branscom answered this question a long time ago
Reply:Well i purged the tank and welded it perfect. I would love to see you guys drill and tap a hold in 12 g material the size of a 3/4 hole. Drilling and tapping a hole on this won't of worked. Any way, thanks for all the help. Still have all 5 on both hands.There is a gadget made called a tank plug that you don't even have tap the hole for. They are made in different diameters starting at about 1/2" in diameter and go up. Biggest I ever used was about an inch and a half. They will even work on slightly irregular shaped holes. It has a head like a bolt and the body tapers to a sharp point and is threaded all the way. Insert it in the hole and turn it with a wrench and it cuts its own threads. They work great on 1/8" thru 1/4" wall tanks.
Reply:Originally Posted by OldtimerThere is a gadget made called a tank plug that you don't even have tap the hole for. They are made in different diameters starting at about 1/2" in diameter and go up. Biggest I ever used was about an inch and a half. They will even work on slightly irregular shaped holes. It has a head like a bolt and the body tapers to a sharp point and is threaded all the way. Insert it in the hole and turn it with a wrench and it cuts its own threads. They work great on 1/8" thru 1/4" wall tanks.
Reply:Originally Posted by zapsterPerfect solution Stay away from potential disasters whenever possible..I for one will Not go near anything that has had fuel of any type in it with anything that gets hot in my hands......zap!
Reply:Well, at least I don't have to worry about Zap being a potential competitor in the oilfield, heheh. Should I tell you how we tap casing for re-entries?The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Don't do that Jolly, he'll be away making a suit of armor 'just in case'    But I'd like to here about it.  For hot taps we weld a casing on spot X then a hole is done mechanically, all while the line is live.I'd rather be hunting........USE ENOUGH HEAT.......Drifting around Aussie welding more pipe up, for something different.....wanting to get home.