I have a 500 gallon bulk tank used for fuel oil that I'm cleaning up to paint. It has about 2 inches of oil in it. There are some deep pits I want to fill with the mig before painting and I'm wondering if there's any danger of explosion? My shop is at about 35° and I'm not getting an overwhelming smell of fumes at the fill spout. I've welded a bung on another fuel oil tank with no issue but that tank was full of fuel, I wasn't concerned about there being too much vapor. So, is there much risk of this becoming a headline story??
That's a great question. I've done like you and welded tanks with fuel in them or flushed them with argon but nothing that big with just a little bit in it. The genset I'm working on is kind of the same situation. The 300 gallon tank has a half inch of sediment on the bottom and no access ports to be able to get a pressure washer into and only an inch and a half pipe drain hole to get stuff out. Owner was talking to someone who suggested cutting holes in the tank and putting bolt on plate covers over the holes when the tank is clean. All I could say about it was to let the talker do the work. I'll be real interested in the comments on here.
Does the oil cover where you are welding? I have done full or half full oil and diesel tanks as long as the area is covered with liquid. Totally empty scares the pants off me.
Dry Ice. When it "melts"/ vaporizes it produces about 700 times its volume in CO2. CO2 is heavier than air so it will lift the air out of the tank. I've used quite a bit of it repairing fuel and hydraulic tanks on equipment without having to remove and wash/purge the tank. You can crush and shovel it right into fuel or oil without worrying about contaminating the system. Don't cap the tank because it will pressurize the compartment. I always used a bit more than I needed just to be safe.
Don't need to crush the dry ice... Just order it in pellets. Used a system that cleaned parts with 1/8 dry ice pellets like a sand blaster. … No sand clean up required. Easy to shovel, it was like rice grains Of course, your supplier has to have such an animal. We never had a problem getting it, with a day's notice at our gas supplier. Came in insulated plastic tubs, The ice would last several days in the closed tub. A beer cooler would work well for smaller quantities.
In the saltbelt of minnesota Ive welded straps on diesel fuel tanks under the strap for miles long. Cut many lids off of race gas 55 gallon drums. Just fill with water to the top, no vapor. Personally saw a top fuel dragster nitro methane tank get tigged. Just stuck the truck exhaust into the tank. Being that is is a fuel oil tank like diesel fuel that will put out a match and wont light with a torch on the ground nowadays just weld it.
I watched a very experienced heavy equipment mechanic do the same thing to a car gas tank. Not something I would do ! I was once was using cutting torch to create some bolt holes in the floorboard of a tractor. I wasn't paying attention and blew hole into the half full fuel tank. No explosion or fire !! I actually used the torch to weld it shut. The top of the fuel tank was part of the floorboard of the cab.
I do a lot of heating oil tank removals for work and never know if or how much is in them until i cut them open with a quick cut or torch. Have not had anything bad happen yet but i did have the fuel in one start to burn a bit.
No precautions before cutting them, YET is the operative word here.
That is true i guess but what options are there on buried tanks that have to be opened to be cleaned out? I have no access to the inside until i cut it open. Always open to ideas.
It has to have somewhere to fill it. Filling with water, steaming with a Hotsy or similar hot water washer, filling with CO2 or dry ice, running exhaust from a vehicle into it are just a few.
I don't take hot metal work on fuel or oil tanks lightly. I personally know of one fatality from an oil drum, I know another guy that nearly lost his arm from an oil drum explosion, and another guy that blew up an OLD lacquer thinner drum with a welding spark that drum was dry and should have been "aired out". I'm not going to take my chances with half azzed "precautions", my insurance and my life don't want to be tested. If I don't like the job, it can go elsewhere.
The exhaust idea sounds interesting. Could i just rip the old fill neck off and put a pipe from a machine exhaust into it for a few minutes? The issue for what ever i put in is that it cant over flow or have to be pumped back out. Its all environmental and would be considered contaminated as soon as it goes in the tank.
Environmental my azz. If you can't make the job safe DON'T do it!
The exhaust idea sounds like the most easy but does the co2 or dry ice work better? Anything inside the tanks has to be taken out by a vac truck and taken to a disposal site. So anything that adds lots of volume is not so good
When I first moved to Walla Walla I went to work for a oil distributor that refurbished old buried fuel tanks. 5,000 to 16,000 gallon, we would cut them open for a 24" manhole {explosion-spring loaded cover} Then pressure wash the inside, weld anti roll over legs on them or install I beam skids and install pump and meter. We would set the tanks on a cross tie on one end then run exhaust from a four cylinder in the low end and push the air out the high end. We used a LEL meter to check the tank before cutting the hatch-anything below 6% was acceptable. I usually ran the torch {because I was the best and steadiest at a continual cut on a 24" x 5/16" or 3/8" material. I cut open Jet-A, diesel, gas and LL100 av-gas. We had a few 10,000 gal tanks that even with a LEL measurement of 5% you made the sign of the cross before starting the cut. We had one that had a 4" X 5' stand pipe still attached on top that we cut. I saw it start to blow smoke back through the cut as I was 1/4 the way around, I yelled hit it and the stand by guys on each end dumped 30 lb fire extinguishers in the end bungs on top. But it went up anyway-It shot a 20' bluish flame out the stand pipe, Two people who worked there also said the tank jumped about 6" upward, it pushed the ends out to a nice round design, looked like a huge hot dog. Afterward we immediately went back to finishing the cut-she was burned out. We converted old tanks for airports to hold their de-icing fluid, shipped them to 20 some states. If your going to try and weld up the pits-the best way is to have a shop roll you some patches that fit the tank curve out of 3/16, Grind off the area around the pits and weld the square patch over it. It looks better and is a way better way to do it than trying to grind out pits and weld that rusty stuff. I know I did a bunch of patch repair to those tanks.
Dry ice and CO2 are the same thing but one is solid and one is a gas. It is -70 deg's. and evaporates leaving nothing behind. CO2 is used for class B (flammable liquids) fire extinguishers.
My Sister and Bother in law live upstate near Titusville, PA, the birth place of oil drilling. They have some oil wells on their property as do most of the neighbors. A young fella who worked for one of his neighbors was killed last year doing a weld repair on an old 2000 gallon crude oil tank. They had done it before, no problems. Luck ran out. Left behind a wife and two young children. I've done it, but it always scares the hell out of me. Take all the safety precautions.
If I had the choice, I would use dry ice in the tank. Lots of volume and it's colder than the surrounding air/gas. Engine exhaust is hot, so heavy fumes could be trapped below the exhaust blanket. So I think …
The one problem often overlooked on using engine exhaust-make sure the engine is running slightly on the lean side, your not making headway running a rich exhaust.
Yep, anybody that has seen what a rich running motor does to it's exhaust when it 'backfires' knows what you mean!!!
We bought this ex rail car tanker to store molasses in some years ago. Even though Qld Rail decommissioned and degassed it, as well as torching off their outlet gear, I was more than a little apprehensive about blowing a hole in the 3/4 thick end wall for our outlet. After hearing all the horror stories about exploding tanks, I believe I shut my eyes and said a quick prayer as I squeezed the lever of the torch.
There's a guy running around my area with a face so scared and no ears, so I don't touch fuel tanks. Period.
If you don't have a LEL meter to measure the combustible gas/oxygen level and a confined space card in your wallet with schooling on working in confined spaces, my best advise- Don't cut or weld on a vessel that had combustible fluids in it, and stay the hell out of the inside if you've had no confined space training. If it doesn't get you from the explosion or fire and you get inside with out proper gear you have a great chance of dying from lack of clean air. JMHO. Another words Don't F@uck with it if you don't know what your doing.
Amen to that.
I personally will NOT weld or cut on any type of fuel tanks. I worked for a general contractor back in the early 80's removing old fuel station tanks. They were supposed to be cleaned and cleared before cutting up, which was done, but one of our guys hit the side of it with a quickee saw and as soon as the blade sparked inside the tank, it exploded. The end blew completely off the tank and decapitated the job foreman. I didn't see it happen, just the aftermath.
Tons of these horror stories out there where Luck just ran out, don't be a add on to the list.
I went for work experience at an oilfield welding shop in high school. I went with one of the owners in a welding truck to repair a crack in a vessel at a refinery. He used a meter to record the gas level and said if it would have been any higher he wouldn't have went in. It was about 85F outside and I could stay in the vessel about 5 minutes before I had to come out to cool off. He could stay in about 10 minutes but was used to it. The vessel had been steamed for 2 weeks and still barely met safe levels! A tank shop I once worked at had a bad accident a couple years after I left. They were coating the inside of a large new tank in the paint shop and a static electricity spark ignited the coating, blowing the tank off the supports. No one was killed but 2 painters were badly injured. One of them took over a year to recover.
Used to weld Gas tanks at a old garage by my Folks house. Old man(Less than my Current Age) sat me down with a Briggs and Stratton tank needed a seam brazed, showed me to open every opening on the tank light the fumes and go to welding while flaming!! Bigger tanks as off a car or pickup he would torch weld full of gas or would fill with water, just depended on price of gas that day. Older story was a small garage in Portage Des Sioux MO had a regular client, asphaltic oil spreader truck, used in chip and seal operations, they had worked on this nuisance many times. Summer day, old dog asleep under another truck, mechanic goes to replace a broken off mudflap bracket ahead of the rear axle, truck had sat inside the garage all night. Short Story longer and more boring guy got geared up, had spot prepped and angle iron clamped up on tank frame, struck a slight arc to know had ground. He woke up in a haze momentarily afterword's, head hurting ears ringing, unable to hear much at all, laying on floor could make out the dog high tailing it across a nearby farm field. Then realized was REALLY bright, like daylight, then really came out of it knowing the roof was gone. Seems the first arc was enough to set off the gasses inside the Open and vented tank, which was now a flat sheet of steel dripping bitumen with insulation and lagging scattered everywhere, one side wall of the garage was GONE, mechanic was lucky to escape minor injuries remained deaf in one ear after, luck was the tank seam was UP and he was Under when it exploded limiting his injury. Truck was destroyed, garage closed never reopened, mechanic retired. Dog WAS found later and would not ever get near a garage shop ever again.
Well that's a smart dog, maybe the owner should have had the dog running the business.
Mechanic told me YEARS Ago he had done this so many times, even had welded o the booms and hatches, never once considered a Bunker hauler as explosive.
Well bunker oil/crude is full of propains until it goes through a process for shipping by rail car or truck. The problem with that is the process doesn't always take place. I know that from a old platform boss for Brinkerhoff Signal Drilling. Crude is a very dangerous substance especially when it's confined in a vessel, even with vapor recovery.
Well there are enough horror stories here to get my attention, I won't be doing the welding without addressing the fumes. The dry ice idea sounds like it would be my best option.. I had to wait for the tank to be near empty so I could both move it to my shop and roll it on its side to address the bottom. Thanks for the other suggestions. Truck Stop, thanks for the tip on patching. I was wondering if I would be able to get the pits clean enough for the mig and I don't want to risk burn through with a stick. Now to decide on the color LOL!
Dry ice, exhaust gas, argon or nitrogen inserting. Burning the fumes, welding with a full tank. It all works 90% of the time. With non-spec Jet A or ULSD tanks, I drain all liquid and vent with air for 12 to 24 hours and sniff with my 4-gas meter until I see 000.0% LEL. Fill out a hot work permit and weld away. I feel safe doing that. I forgot to mention that I bond the tanks with a cable to a good watch ground as best practice. Then, I fill out a all-clean certificate along with the hot-work permit. My experience with fuel oil tanks is that with venting, they "dry" up pretty fast. I use confined space style vent fans with trunk hoses. Push the air in, don't draw the vapors through the fan! That's how to make a blow torch. Intrinsically safe fans are available, but big $$$. I also use air driven Venturi fans that are 100% intrinsically safe when I have a big air source. Venting ULG or methanol tanks require some extra steps. I try to flush gasoline tankers with ULSD before working on them. Gasoline tends to be latent. I'll vent a gas tanker clean and the next day the LEL will jump back to an unsafe level. I'm in the tanker biz, so I deal with this all the time.
Argon can be used but very expensive! Diesel fuel tanks are probably the easiest to get to safe levels for welding and cutting. Semi diesel fuel tanks are repaired everyday. Gasoline requires much more stringent cleaning requirements.
I was going to say that too. I've never seen a problem welding on a diesel tank provided a few basic precautions were taken. TBH back in the day before Hot Work Permits and the like we'd weld minor cracks in welded diesel tank seams by filling the tank right up to the filler neck with diesel, close the cap, strike the arc and weld away to your heart's content. Gasoline/petrol or heavy oils/aromatics, now that's another story altogether.........
I've repaired rust leaks on diesel tanks using JB Bond and it lasted years.
As I got further into cleaning the tank for painting I discovered the pitting was much more extensive than I thought, the bottom third of the tank would need replaced. Priced a new tank, around $1200. Went on Facebook marketplace and found a clean 500 gallon tank with pump for $300. Went to look at it this morning and it has about 40 gallons of off road diesel in it! It's in the back of my pickup now, I'll drop it at my shop after lunch. Thanks to everyone who gave advice. If anyone wants my old tank you're welcome to it, I can load it too.
The look on people’s faces when they start sand-blasting something like a tank “just to clean the loose scale off” before painting, all to see it fall into a heap of rust before their eyes, never fails to raise a chuckle. I feel your pain Steve.
Thanks Nige. I really can't complain, I was given the tank over 20 years ago and always intended to paint it because the paint was peeling in areas. It sat on the ground all that time too on just the skids. Had I attempted this back then the outcome would probably be different and I've gotten all these years use out of it besides. I'm sitting here thinking more about it and I think it's over 30 years ago!
I have seen some hunks of rust come off the under side of bridge beams that weighed upwards of 200 pounds. enough to seriously maim a person
And your safety person does not enter the confined space!