Material of construction for Sulphuric acid storage tank.

Hello nandan

Have a look here: http://www.tankteam.com/sulfuric_acid.htm

Also here: http://www.polyprocessing.com/pdf/literature/PositionStatements/SULFURIC_ACID.pdf

An extra precaution is often done, by lining the inside of the steel tank with polythene.

The tank must be vented, of course.

Because the concentrated acid weighs twice as much as the same volume of water, special techniques, bracing, and fixing are extremely important.

If you are installing tanks in a seismic zone (earthquake liable), baffles are often internally installed, polythene coated once again, to minimise liquid movement during a seismic event.

Tanks normally sit inside a tray type of holder, with its sides around a meter high, with external piping to outside covered tank, with grilles/u-bends to prevent rodent or insect access to the system, in case of sudden and catastrophic leak.

Tanks must be emptied regularly, generally once per year, and a full inspection done, of the entire storage and emergency drain, looking for corrosion and leaks.

Safe use and storage of this chemical is vital, because an escape is unforgiving to people, animals and plant/equipment.

Hope that assists you, please call back with.......

An echo from secondary school chemistry days suggests that rubber 'vulcanises' when subjected to sulphuric acid?

In many places, conc. sulphuric is kept quite happily in mild steel tanks without lining. Above about 92% there isn't a problem. A problem arises when H₂O is brought near it, and the concentration starts to drop; all of a sudden the tank dissolves and there's quite a mess to clean up.

PVDF is quite popular for diluted sulphuric acid piping. It can withstand the temperature stresses from heat-of-dilution.

Any supplier of conc. sulphuric can give advice on installation best practice.

Use Mild Steel for the construction of sulphuric acid storage tank.

Tehseen

I agree.

No lining will improve the self protection offered by mild Steel--carbon Steel with 0.1>015% Carbon i.e.

Mild steel is more corrosion resistant as compare to stainless steel against concentrated sulphuric acid environment. Internally acid resistant rubber lined mild steel storage tanks are better, if they are properly sealed. Tehseen

Use Mild Steel Plates for the construction of highly concentrated 98.5% purity level Sulfuric acid tanks, apply anodic protection for the insides of the walls, for the bottom of the tank keep it bare and apply Cathodic Protection. The shell and the top should be coated with chemical acid resistant coating from outsides.
If you need any consultancy , design, installation, supply of materials and commissioning of anodic and cathodic protection systems please contact,

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Dear Everybody,

Why don't use carbon steel tank with inside lead (Pb) covering layer or plate? Because lead isn't enviromental friendly metal?

Tibor Nagy (Hungary)

PS: Sorry for the language mistakes, I don't speek english just read only :)

Hello Hungarian Guest,

Your English is fine, I understood you perfectly. A lead lining should work well as long as long as the sulfuric acid does not also contact a second metal and create a galvanic cell involving the lead lining. Although lead is above hydrogen in the electro-activity series (and can therefore theoretically react with acids), a thin insoluble layer of lead sulfate protects lead from further reaction.

But I must stress that I have only theory to support my statements -- I have no direct experience with storage tanks. So if I give bad advice, I hope that experienced engineers will correct my statements so that I can learn. Instead of lead, my first guess would have been to use copper since it will not react with sulfuric acid. But I suspect that this would cost to much.

... oxidizing acids (e.g. HNO3, H2SO4) can solve copper.

Yes, you are correct. I already knew that nitric acid reacted with copper even at room temperature (I have used this reaction to make copper nitrate), but I had only considered room-temperature sulfuric acid, which gives the appearance of no reaction. I checked your statement and learned that copper definitely reacts with *hot* sulfuric acid. So it seems safe to assume that the reaction also occurs at room-temperature, just at a very slow rate. But any reaction, no matter how slow, is of course unacceptable for a storage tank.

If moisture (humidity) is drawn into the tank as it breathes, the conc. sulfuric acid will absorb this water and become diluted at the surface. The diluted acid will etch a CS tank wall if the level does not change for a long time. I know of one tank that failed this way. We added a dry nitrogen pad to the replacement tank to prevent this.

At lower concentrations more exotic metal is required (SS is not adequate!). Alloy 20 or monel are typical. CS is fine for conc. acid. Plastic may work fine, but "steel is real" and maybe less expensive.

The tank can be made of carbon steel, however, it will have to be PWHT (Post Weld Heat Treated). Otherwise the acid will attack the welds heat affected zone. Note: When heat treating for service the tank must be heated to temperature (it cannot be heated to a lower temperature and then have a longer soak period).

The tank should be painted inside with a Phenolic paint, applied to a sand blasted surface. This paint may require that it be force dried, (Heated to about 200 degrees F. between coats) and a final bake at about 400 degrees F. This temperature is metal temperature.

Dont know about current practices, but MANY years ago the practice was to use a lead lining in a mild steel tank.

Yes..you r right. But MS tank with Monel (Cupro-Nickel) lining is best option i feel.