Blasting Gas Tanks

nah, no need. Two sticks of dynamite in the vent should do the trick! Wollar! no rust! no Paint! No Tank! No Neighbourhood. Mind you whats left of the neighbours are going to be pretty dirty on you!

Depending on the surface being blasted grit or garnet will do a good job on the tanks( steel shot doesnt generate as much static as Garnet but the grit is more aggressive and will remove more material)you will generate a fair bit of static so you should ensure the tanks are empty of product purged and tested before any work commences. Also consider disposal of waste as the left over product usually becomes prescribed waste to the paint etc that contaminates the grit.

An experienced contractor is ussually a better option cost wise once waste disposal etc is factored into the cost of job.

also consider the petrol tank may not be classed as a pressure vessel but the gas tank will be if you blast the outside of the tank you will need to have it inspected and recertified before putting it back into service.

Agreed, do not do it! No matter what you use, static will build up and cause a very dangerous situation, or you could accidentally wear through a corroded section and the gas would leak out, etc.... This idea will not end well.

All fuel must be removed and all of the vapor must be purged. You should get someone who knows what they are doing. If you must do it yourself, drain the tanks and leave them as open as possible for a long time - like a week or two - to be sure all of the vapor gets out.

Once you are sure they are totally empty, sandblasting with sand or dry ice pellets, or any other normal paint removal process should work.

There is no way around doing this right....

And connect a ground wire from the tank to the blaster enclosure.

actually you are much safer having a completely FULL tank. Empty tanks always have vvapour and air present whereas full tanks have neither vapour nor air. Diesel will not ignite from an electric spark whereas petrol will but it cannot burn as a liquid. Wide cut kerosene ( cheap AV kero) will burn as a liquid AND ignite from a spark so the only way you should clean the tank is to earth it first and to the cleaner amchine plus drain and fill with inert liquid of a distinct colour (Blue). to keep the residue from fuming

the best means to do this is to use high pressure hot water from a steam cleaner. if its really hard to shift, like rust, you can get an attachment which adds glass beads into the spray. you will have to seal the tank and keep the pressure unit well away it has a naked flame in it for the boiler. you should also keep an eye out for holes appearing in the tank when you remove the paint! Internal condensation can rust tanks out from the inside, particularly at the bottom, leaving the paint to keep the fuel in.

Rebecca

I agree with Butcher - except you would need to force purge for weeks - the product will impregnate the steel etc and vent for weeks if not months !

Filling with water is ok but you then have to deal with a lot of dirty water and that may have environmental implications.

Why do you want to do this?

you can drain the tank and then use high pressure live steam to clean the interior, then backfill/purge with dry nitrogen and you should be able to work on the exterior without a problem and not generate too much contaminated water in the process. grounding the tank is an excellent idea as well. Some blasting media is piezoelectric and will generate high voltage sparks from impact. Others are prone to generating static electricity, some will do both. As others have said, this is not a backyard DIY procedure, you really need to let an expert do the job.

I don't see why you can't just use a sandblaster to take the paint off. You can get different grades of grit to use in it. If you're worried about any kind of spark, I don't think a sand blaster will produce one but all you would need to do is ground the tank to avoid issues with static electricity just to be safe.

most grit media is piezoelectric, and the tank will build up a static charge. grounding will help (but not eliminate!) with static but not with piezoelectricity.

If she does this, she is putting her life as well as the lives of those around her at risk. There are safer ways of doing this.

Besides, the grit will contaminate the fuel anyway.

Then what about using paint stripper?

What about the gas? know thee of disposable contractors who can enter a live gas tank and add paint stripper - of course assuming that the gas is heavier than air and doesn't just vent out when you open the manway on the roof I presume !

"gas" in this case is gasoline.

And I'm pretty sure the paint is on the outside of the tank.

The gas would act as a solvent to the stripper and it's my understanding that it's the outside of the tanks that we're dealing with and the tanks are sealed.

You can use silicon carbide grit about 24.36 size with low pressure blasting to blast clean light gage materials like a gas or diesel tank, you can also use walnut shell for this purpose and be better than silicon carbide. Use low pressure, that is the secret so the tank does not warp

Thank you Vishmayor. What size walnut shell would you use? 12/20?

Have you seen this process done. Do you agree with grounding the blasting equipment?

Have you had experience in blasting with walnut shell before? Particularly in applications like this?

I have seen automobile fuel tanks repaired many times. First remove as much of the fuel as possible. Use low volume of any inert gas purge as much of the fumes as possible. Gradually increase the volume. I have seen this done with exhaust gas from an automobile, but do not think it was wise. Once you have purged all remaining gas fumes from the tank, try to contain the inert gas inside the tank by sealing the openings as well as possible. Consider allowing a slow feeding of the inert gas while working on the tank. Bond all things that working near the wank. Fuel tank to air compressor. Fuel tank to spray nozzle. Bond yourself to the tank. You must keep any static from building up and then transferring. Walnut shells, pecan shells, plastic chips, glass beads etc. The list of blast media is very long. are you repairing a fuel tank on an automobile. If so you might want to consider replacement tanks. There are companies manufacturing new tanks for many vehicles. The rust in the old tank will never bother you again if you throw out the old tank. www.eastwood.com sells a liquid that is used to seal the inside of old gas tanks. This might be an option for you. Please send back more information on the type of tanks. All here will appreciate the information.

Thes are very large fuel tanks with a refinery. Double hauled.

Dear Rebbeca,

I don't know why you want to sand blast these tanks. I do know that, empty and dry or full to the brim, if you create even a pinhole the gases will combine, temporarily, with the water and spread around a bit. When critical mass is reached you will get a huge explosion and the gas/water mixture will also ignite and blow up anything it gets close to.

If I haven't scared you enough with this then I suggest you visit a burn center to see what you will look like, provided you survived the initial explosion.

If the tanks are rusty, use a wire brush to GENTLY remove the surface rust and then just paint over the rest. I believe that is the safest method and it won't cost you . . . You.

Orpheuse

No comment

Hello rebecca7

How is <"No comment">, not a comment in itself?

Kind Regards....

We are professionals and do not look for comments like 'if I have not scared you enough'. We are on this site to communicate intellectual suggestions only. Thank you for your comments except the obnoxious one.

rebecca7:

Where is the tank(s) located, what industry? What is the type paint need removed?

Are you set upon blasting? Other mediums are speedier and more effective inside a chemical envelope if refinery is the location. A chemical application followed by a hi temp/pressure water washer set-up perhaps, no static charge concerns involved.

Suggest you research methods used to remove paint from large aircraft.

Client is set on blasting and has done it before with walnut shell. Was verifying if this was a good application.

I know that walnut shells are used to blast aluminum; for example a cylinder head. The principle is that "sand" is too abrasive for the soft metal. Also walnut shells won't damage the hardened valve seats.

Bead blast is another alternative. Select the proper bead for the application. Recyle the bends. The product can be purchased in bags according to specification.

Finally, there is good old sand. It breaks down is hazardous to the workers so wear breathing protection. However it is cheap and would work on steel.

Was there a particular reason not to use sand on these tanks? I haven't been following this thread that closely and don't seem to recall whether we have yet learned what size or material the tank is made of.

Some of these details might be helpful in making the determination.

The tank is like 10 feet in diameter and 20 to 40 feet high. Sand will spark.

rebecca7,

Walnut shells are an effective descaling product yes.

Mention by THE JMAN #30 of dry ice crystals may be a toss up between cost effectiveness based upon clean up.

Walnut shells and the removed materials will each vacuum nicely.

Why would you subject any plant operation to free fly or floating abrasive field of contact?

rebecca7,

Perhaps I missed prior mention, but there are two other types of alternative shot "blasting" media that may be what you are looking for:

The first is called "Sponge Jet", which is a low rebound, low dust media comprised of aluminum oxide abrasive grit embedded in a particulate "sponge" carrier

http://www.spongejet.com/

The other is dry ice blasting, using dry ice pellets as the abrasive media.

An advantage of this is that the blasting media itself sublimates into CO₂ gas, and is therefore not an issue for disposal or recycling. Once you are done blasting, you are only left with the removed bits of coating itself.

One company that manufactures this equipment is Cold Jet -

(http://www.coldjet.com/en/information/what-is-dry-ice-blasting.php )

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Just my $0.02...

Do you have to blast? I have a product that can be applied to a SSPC-SP2 surface prep, requiring no sandblasting and it the tanks are coated with lead-based paint, it is also patented as a lead-based paint and asbestos encapsulator. The product is tested and proven and has been used on many projects. My latest project was painting lead-based painted, rusty deluge tanks at Ft. Bragg. Eliminate sandblasting and protect the landfills from the tons of waste generated from this practice. If you are interested, respond back and I will forward you the information on the product that eliminates sandblasting of metal structures.