Best Practices For Sulfuric Acid Storage Tank Design

Sulfuric acid is one of the most widely used chemicals in the United States. More sulfuric acid is produced every year than any other chemical. It has a multitude of industry-specific uses, such as the production of other chemicals, dyes and pigments, water and water treatment, and fertilizers.

This heavy, corrosive chemical requires a specifically designed storage system. That’s why Poly Processing follows guidelines that help ensure safety and enhanced useful tank life.

In this article, we’ll look at why storing sulfuric acid is such a challenge, and how we’ve adapted our tank system requirements to resolve these challenges. You’ll learn about our tank storage requirements for your own storage needs and get access to a downloadable guide for your reference.

What Is Sulfuric Acid?

Sulfuric acid is a highly corrosive mineral acid that challenges traditional chemical storage options. This pungent, colorless to slightly yellow viscous liquid is dyed dark brown during production to alert people to its hazards. 

The biggest challenge in storing sulfuric acid is that it’s an aggressive oxidizer. This tests the strength and design of any storage tank system. Poly Processing Company’s tanks and fittings can be combined specifically to store sulfuric acid and greatly reduce the risks.

Storage Challenges

Sulfuric acid presents serious storage issues because it’s a very heavy chemical, especially at high concentrations. At 93-98% concentration, it is nearly twice the weight of water. It’s also an aggressive chemical that oxidizes plastic and corrodes metals.

Sulfuric acid poses the following serious storage challenges:

• Sulfuric acid is extremely heavy and will test the mechanical integrity of your storage tank. The inherent weight of sulfuric acid requires a strong material that can withstand the static load pressure constantly pressing against the bottom third of the storage tank.
• Sulfuric acid is an aggressive oxidizer. You must take appropriate safeguards to prevent the tank’s material from degrading, becoming brittle, and cracking—which could result in leaks or tank failure.
• If sulfuric acid makes contact with water, it creates a toxic sulfuric acid aerosol fume or a potential explosion.
• Sulfuric acid can create a highly flammable hydrogen gas if it is spilled on metals.
• Skin and other bodily burns from sulfuric acid can be more serious than burns from other strong acids. Sulfuric acid dehydrates whatever it touches, and the heat caused by that reaction with water can create secondary thermal damage.
• When mixing or blending chemicals with sulfuric acid, an exothermic reaction may occur, and the heat of the chemical can cause damage if not properly addressed.

All of these things should be taken into consideration when designing your sulfuric acid storage tank.

For more information on sulfuric acid challenges, read our sulfuric acid storage guide.

Storage Guidelines to Minimize Safety Risks

When storing sulfuric acid in a Poly Processing tank, just remember the 11/15 rule. You can use any tank up to 11,000 gallons and up to 15 feet tall. This includes the Vertical, IMFO®, Sloped-Bottom IMFO®, and SAFE-Tank® Systems.

Other storage requirements for sulfuric acid vary, depending on the concentration of the chemical.

• Concentrations of 93-98 percent: Because the weight is up to 16 pounds per gallon, 93-98% concentrated sulfuric acid must be stored in a tank that has a 2.2 specific gravity wall thickness. The OR-1000® System with PVC fittings, Viton Gaskets, and 316 Stainless Steel bolts are also required for this concentration.
• Concentrations from 80 percent to less than 93 percent: Because this lower concentration of sulfuric acid can be corrosive to stainless steel, alloy C-276 bolts with Viton gaskets and PVC fittings are required along with a 2.2 specific gravity tank and the industry-leading OR-1000 System.
• Concentrations of less than 80 percent: A 2.2 SPG tank with the OR-1000 System. The fittings required are PVC, with Viton gaskets and alloy C-276 bolts.
• Tank recommendations for concentrations of 98 percent or less: Poly Processing's double-walled (SAFE-Tank) cross-linked polyethylene tank with the OR-1000 system is necessary if no secondary containment is available. If containment is provided, a full-discharge Vertical IMFO tank or Sloped Bottom IMFO tank are excellent choices.
  

In all cases, the OR-1000 antioxidant system must be used. The OR-1000 system is designed to  provide longer useful life by reducing the oxidation of the polyethylene tank system.

For more specific information on our Sulfuric Acid storage tank systems and options, get your copy of our Sulfuric Acid Position Statement.