H2SO4 storage tanks · molded in Willis, TexasMon–Fri · 936-228-1520
Storage guide
What sulfuric acid is, how it behaves and how to store it safely in a plastic tank, with property and hazard data from PubChem.
What it is
Sulfuric acid, also called oil of vitriol, is a dense, oily, odorless liquid that ranges from colorless to dark brown depending on purity. It mixes with water in any proportion and releases a great deal of heat when it does.
That weight is why every sulfuric acid tank we list is rated 1.9 or 2.2 specific gravity, and its corrosiveness is why each one is matched to the acid on our compatibility chart.
Source: Sulfuric Acid, PubChem CID 1118, National Library of Medicine.
Hazards
Concentrated sulfuric acid causes severe burns and reacts violently with many materials. Always follow the safety data sheet from your acid supplier.
H314: Causes severe skin burns and eye damage. Many suppliers also list H290: May be corrosive to metals.
Health 3, Fire 0, Instability 2. It does not burn, but it can ignite combustibles such as wood, paper and clothing on contact.
UN 1830 for sulfuric acid, UN 1832 for spent acid and UN 1831 for fuming acid. Emergency Response Guide 137.
Serious effects by every route: skin, eyes, inhalation of mist and ingestion. Wear goggles, a face shield, gloves and chemical-resistant clothing.
Hazard data: PubChem safety and hazards.
Where it’s used
Sulfuric acid goes into fertilizers, refined fuels, batteries, metal finishing and much more, so it is stored at farms, plants and treatment facilities everywhere.
Major producers ship it in enormous volumes. BASF, one of the world’s largest chemical companies, lists sulfuric acid among its bulk chemicals, supplies it to the fibers, chemical, metalworking, leather and textile industries, and ships it only by river barge.
Sources: PubChem, Use and Manufacturing; BASF Bulk Chemicals.
Independent research
Not all polyethylene tanks hold up the same way. ExxonMobil Chemical soaked rotomolded samples of linear HDPE, linear LLDPE and two crosslinked polyethylenes in 97% sulfuric acid for up to 4,000 hours at about 70 °F, then tested how tough they stayed.
Cold impact strength after 4,000 hours in 97% sulfuric acid
Both crosslinked resins started above 200 ft-lb. ARM impact test at −40 °C on ¼″ rotomolded samples. Data: ExxonMobil Chemical, “Comparison of Linear and Crosslink Polyethylenes in Certain Acid and Base Environments,” Tip from Technology, 2003.
Why it happens: concentrated sulfuric acid is an oxidizer. It strips hydrogen from polyethylene chains and breaks them apart at the surface, which makes the plastic brittle. The researchers caution that the results apply to the specific conditions tested and can’t be extrapolated to other chemicals or test methods. The HDPE tanks Bailiff molds are linear HDPE, not crosslinked. See our resin.
Source: ExxonMobil Chemical, “Comparison of Linear and Crosslink Polyethylenes in Certain Acid and Base Environments,” Tip from Technology, 2003. Results summarized by Bailiff Enterprises.
A copy of the complete report is available from Bailiff by email request.
Our resin
The HDPE tanks we mold are made from linear high-density polyethylene, never crosslinked polyethylene. Our standard resin is Dow RESILITY™ DPDB-3220 NT 7. We may also use a comparable linear HDPE rotomolding resin with the same key qualities, such as Chevron Phillips Marlex® HMN TR-942.
Both resins are linear HDPE designed for rotomolded chemical and potable water tanks, with the same nominal density and melt index as the linear HDPE grade in the ExxonMobil sulfuric acid study above. They are different resins from that study’s, so its results are not a test of them, but they belong to the same linear family that held up in 97% acid.
| Typical property | Dow DPDB-3220 | Marlex HMN TR-942 |
|---|---|---|
| Resin type | Linear HDPE | Linear HDPE (ethylene-hexene) |
| Density | 0.942 g/cm³ | 0.943 g/cm³ |
| Melt index | 2.0 g/10 min | 2.0 g/10 min |
| ARM impact, ¼″, −40° | > 195 ft-lb | 180 ft-lb |
| ESCR, F50, 100% Igepal | > 500 h | 700 h |
| Tensile yield | 3,500 psi | 3,000 psi |
| Melting point | 262 °F | 266 °F |
| UV stabilization | UV-20+ | > UV-20 |
| NSF 61 | Yes | Yes |
Typical values, not specifications, from the Dow RESILITY™ DPDB-3220 NT 7 (Form 400-00391082en) and Chevron Phillips Marlex® HMN TR-942 (rev. August 2021) technical data sheets. Test specimens and some methods differ between producers, so small differences are not direct comparisons.
Best practices
Guidance drawn from PubChem storage data and four decades of building acid tanks.
HDPE to 93%, PVDF for the best resistance at high concentration, polypropylene for hot acid up to 75%. See ratings.
In ExxonMobil testing, crosslinked polyethylene turned brittle in 97% acid while linear HDPE held its strength. Bailiff-molded HDPE tanks are linear. See the study.
Concentrated acid is about 1.84 times as heavy as water. A tank rated below the liquid’s specific gravity can fail.
A double wall tank captures leaks and keeps fumes from spilled acid inside the outer wall.
Sulfuric acid draws moisture from the air and releases strong heat when mixed with water. Fill only clean, dry tanks and keep lids and fittings sealed.
Dilute acid attacks most metals and can release hydrogen gas. Use Hastelloy hardware and avoid 316 stainless above 10%.
Store away from combustibles, bases, carbides, chlorates, nitrates and powdered metals, in a cool, dry, well-ventilated area.
Pure acid is solid below 51 °F. In cold climates choose an insulated tank with heat tracing.
Viton® is rated Excellent from 1% to 93%. No welded flanges in the sidewall for sulfuric acid. See fittings.
This guide is general information. Always follow the safety data sheet from your acid supplier and your local fire and environmental codes. Full chemical data is available on PubChem.
FAQ
A plastic tank in HDPE, PVDF or polypropylene, matched to the concentration and rated at least 1.9 specific gravity. We recommend a double wall tank to contain leaks and fumes.
Concentrated sulfuric acid (96–98%) has a specific gravity of about 1.84 and weighs about 15 pounds per gallon, according to PubChem.
Yes. Pure sulfuric acid is a solid below 51 °F (10 °C), so highly concentrated acid stored outdoors in cold climates may need insulation and heat tracing.
Dilute sulfuric acid attacks most metals and can release flammable hydrogen gas. Plastic tanks are not attacked at the concentrations they are rated for.
In an ExxonMobil Chemical study, crosslinked polyethylene lost about 90% of its cold impact strength and all of its ductility within 1,000 hours in 97% sulfuric acid, while linear HDPE retained most of its strength through 4,000 hours. HDPE tanks molded by Bailiff are linear HDPE, made from Dow RESILITY™ DPDB-3220 NT 7 or a comparable linear HDPE resin. A copy of the full study is available from Bailiff by email request: dmiller@plasticstoragetanks.com.
Tanks used for sulfuric acid carry a limited one-year warranty from the date of manufacture, and installed fittings carry a one-year warranty.
UN 1830 for sulfuric acid, UN 1832 for spent sulfuric acid and UN 1831 for fuming sulfuric acid. It ships as a Class 8 corrosive.
Send the acid concentration, temperature, volume and fittings you need. We’ll match the resin, SG rating and gaskets and send a quote.