H2SO4 storage tanks · outfitted in Willis, TexasMon–Fri · 936-228-1520
Buying guide
A step-by-step guide to picking the right tank for your acid: the resin for your concentration and temperature, a 1.9 or 2.2 specific gravity rating, containment, venting and fittings. It uses the same ratings as our compatibility chart.
The short version
Concentration, highest and lowest temperature, volume, and indoor or outdoor. Every other choice follows from these.
HDPE for the lowest cost to 93%, PVDF for the best resistance at high concentration, polypropylene for hot acid up to 75%.
Both carry concentrated acid. 2.2 SG adds wall thickness and margin.
A double wall tank, or a single wall tank inside a dike or basin.
An atmospheric tank must breathe, and concentrated acid pulls moisture from the air it breathes in.
Fittings, gaskets and bolts must suit your concentration too. Viton® gaskets; PVDF fittings above 75%.
Step 1
Concentration decides the resin and fittings. Temperature decides whether the resin can take it, and whether the acid could freeze. Get the exact concentration from your supplier’s safety data sheet.
| Concentration | Specific gravity | Freezing point | What it means for the tank |
|---|---|---|---|
| 93% (66° Baumé) | about 1.83 | about −21 °F (−29.5 °C) | Heavy acid: use a 1.9 or 2.2 SG tank. Unlikely to freeze in most US climates. |
| 96–98% | 1.84 | about 37 °F (3 °C) | Can freeze on a cold night. Plan for insulation and heat tracing outdoors. Call us before storing 93–98% acid. |
| 100% (pure) | — | 51 °F (10 °C) | Solid below 51 °F. |
Freezing points: Alliance Chemical technical data sheet for 93% sulfuric acid and its sulfuric acid concentration guide; pure acid from PubChem. Values vary slightly by source and purity. Weaker acid is lighter than concentrated acid, but always choose a tank rated at or above your acid’s specific gravity.
Step 2
We mold sulfuric acid tanks in three resins. Ratings are from our chemical compatibility database (A = Excellent, B = Good, C = Fair).
| Acid strength | HDPE | Polypropylene | PVDF (Kynar®) |
|---|---|---|---|
| 1–10% dilute | Excellent | Excellent | Excellent |
| 10–75% mid-strength | Excellent | Excellent | Excellent |
| 75–93% concentrated | Good | Fair — not recommended | Excellent |
| 93–98% commercial grade | Above the range of our database. Call us before storing 93–98% acid so we can review your application. | ||
| Continuous temperature | About 120 °F | Up to 200 °F | Highest of the three |
| Relative cost | Lowest | Moderate | Highest |
The most economical tank for sulfuric acid to 93% at normal temperatures. Bailiff HDPE tanks are linear HDPE, never crosslinked. In ExxonMobil testing in 97% acid, crosslinked polyethylene turned brittle while linear HDPE held its strength. HDPE tanks · See the study
The only resin rated Excellent from 75% to 93%, with the highest temperature and purity performance we offer. Common for high-purity acid such as semiconductor wet etching. PVDF tanks
Rated Excellent to 75% and good for continuous use up to 200 °F, which suits hot plating and process baths. Not for acid above 75%. Polypropylene tanks
Compatibility ratings are for the acid alone. Temperature and impurities change how a resin performs, so send us both and we’ll confirm the match. Full compatibility chart.
Step 3
Specific gravity (SG) is the heaviest liquid a tank is built to hold. Water is 1.0. Concentrated sulfuric acid is about 1.84, or roughly 15 pounds per gallon, so we list only tanks rated 1.9 or 2.2 SG for sulfuric acid.
| 1.9 SG | 2.2 SG | |
|---|---|---|
| Holds 93–98% acid (SG 1.83–1.84) | Yes | Yes |
| Wall thickness | Standard heavy-duty wall | Thicker wall |
| Margin above 1.84 | Small | Larger |
| Price and weight | Lower | Higher |
| Resins | HDPE, polypropylene, PVDF | HDPE and polypropylene (PVDF tanks are listed in 1.9 SG) |
Dilute and mid-strength acid, which is lighter than concentrated acid, and concentrated acid stored at moderate temperatures where cost matters.
Concentrated 93–98% acid when you want more wall and more margin above the acid’s 1.84 rating: tanks in full sun or hot climates, heavy daily cycling, or long planned service life. We can quote both so you can compare.
Live sizes and prices for each rating are on every tank page, for example HDPE vertical tanks.
Step 4
If the tank ever leaks, something has to hold the acid. Most bulk sulfuric acid installations need containment, and your local fire code official has the final say.
Under the International Fire Code as many cities adopt it, outdoor tanks holding more than 1,000 gallons of corrosive liquids in total need secondary containment. Indoors, rooms with any vessel over 55 gallons need spill control. Containment is generally sized to hold the largest tank. Check your local code before you buy.
A sealed outer tank around the inner tank catches leaks and acid fumes without building a dike, and an interstitial leak detector can alarm if the inner tank leaks. HDPE double wall · PVDF double wall
A single wall tank inside an acid-resistant dike or containment basin works too. Size it for the full tank, plus any rain it may collect if it’s outdoors and uncovered.
Step 5
Our tanks are atmospheric tanks: they must vent freely as they fill, empty and warm up. They must never be pressurized or put under vacuum.
The vent has to pass air as fast as acid comes in, which matters most when a truck unloads with air pressure. Tell us how the tank will be filled so we size the vent.
Concentrated sulfuric acid is hygroscopic: it absorbs water from the air the tank breathes in. Over time the top layer gets weaker and more corrosive. A desiccant dryer on the vent dries incoming air.
Desiccant must be checked and replaced on schedule. Saturated or plugged media can restrict the vent, and a blocked vent can damage a tank. Never let a dryer become the tank’s only, unprotected opening.
We supply screened U-vents and can discuss vent options for your site. Vents and fittings. Moisture guidance: Synergy Engineering.
Step 6
A tank is only as good as its weakest wetted part. We specify and install fittings at our Willis, Texas plant so the tank arrives ready to connect.
| Part | Up to 75% | 75% to 93% |
|---|---|---|
| Fittings | PVC, CPVC, polypropylene, HDPE and PVDF all Excellent | PVDF Excellent, HDPE Good; CPVC and polypropylene Fair; PVC severely attacked |
| Gaskets | Viton® Excellent; EPDM Good above 10% | Viton® Excellent; Buna-N only Fair |
| Bolts and hardware | Hastelloy rated Good throughout. Avoid 316 stainless above 10% and titanium at any strength. | |
Checklist
Sulfuric acid tanks carry a limited one-year warranty. Warranty terms · Installation guide
FAQ
For most storage up to 93% at normal temperatures, linear HDPE is the most economical choice. PVDF is the only resin rated Excellent from 75% to 93% and handles the highest temperatures. Polypropylene suits hot acid up to 75%.
Concentrated acid is about 1.84 SG, so a 1.9 SG tank is rated for it. A 2.2 SG tank adds wall thickness and margin. Call us before storing 93–98% acid so we can review your application and quote both.
Yes. 96–98% acid freezes at about 37 °F, while 93% acid stays liquid to well below 0 °F. Insulation and heat tracing protect outdoor tanks of concentrated acid.
You need some form of secondary containment for most bulk installations. A double wall tank is one way; a dike or basin is another. Your local fire code official decides what is required at your site.
An atmospheric tank must breathe freely or it can be damaged by pressure or vacuum. Concentrated acid also absorbs moisture from incoming air, which a desiccant dryer can prevent.
Sources: PubChem, Sulfuric Acid (CID 1118); Alliance Chemical, 93% sulfuric acid technical data sheet; Alliance Chemical, sulfuric acid concentration guide; Synergy Engineering, atmospheric tank breathing; 2015 International Fire Code Chapter 54 as adopted by Seattle; ExxonMobil Chemical, “Comparison of Linear and Crosslink Polyethylenes in Certain Acid and Base Environments,” 2003. Ratings for HDPE, polypropylene and PVDF are from the Bailiff chemical compatibility database.
Send the acid concentration, temperature, volume and fittings you need. We’ll match the resin, SG rating and gaskets and send a quote.