Chemical Compatibility Guide: What Can and Can't Go in Your IBC Tote

Understanding HDPE Chemical Compatibility

High-density polyethylene is the standard material for the inner bottle of most IBC totes, and for good reason. HDPE offers excellent resistance to a wide range of chemicals, is lightweight, durable, and cost-effective. However, HDPE is not universally compatible with all chemicals. Storing the wrong substance in an HDPE IBC can lead to container failure, leaks, environmental contamination, and serious safety hazards. Understanding chemical compatibility is not just good practice; it is essential for safe operations.

This guide provides a thorough overview of HDPE chemical compatibility, covering common industrial chemicals, the factors that influence compatibility, and the testing and rating systems used to make informed decisions. While this guide is comprehensive, it is not a substitute for testing with your specific chemical formulation under your specific conditions. Always verify compatibility with the IBC manufacturer and the chemical supplier before filling.

How Chemical Compatibility Is Rated

Chemical compatibility is typically rated on a four-level scale:

A - Excellent: No attack. The chemical can be stored long-term in HDPE at room temperature with no measurable degradation, swelling, or permeation.
B - Good: Minor interaction. The chemical may cause slight swelling or minor surface effects over extended periods, but the container remains functional and safe for normal storage durations.
C - Fair: Moderate attack. The chemical causes noticeable swelling, softening, or partial dissolution of HDPE. Short-term contact may be acceptable, but long-term storage is not recommended.
D - Not Recommended: Severe attack. The chemical will damage, dissolve, or permeate through HDPE, leading to container failure. Do not use HDPE containers for these chemicals.

These ratings assume room temperature (approximately 68 to 77 degrees Fahrenheit) and the chemical at its typical working concentration. Higher temperatures and higher concentrations generally reduce compatibility.

Chemicals That Are Safe for HDPE IBCs (Rating A)

HDPE is remarkably resistant to many common chemicals. The following categories and specific substances generally receive an A or excellent compatibility rating:

Acids (Dilute to Moderate Concentrations)

Hydrochloric acid up to 37% concentration
Sulfuric acid up to 70% concentration
Phosphoric acid up to 85% concentration
Nitric acid up to 50% concentration (higher concentrations are a B rating)
Acetic acid (vinegar) up to 50% concentration
Citric acid in solution
Hydrofluoric acid up to 50% concentration

Bases and Alkalis

Sodium hydroxide (caustic soda/lye) up to 50% concentration
Potassium hydroxide up to 50% concentration
Ammonium hydroxide (ammonia solution) up to 30% concentration
Calcium hydroxide (lime water)
Sodium carbonate (soda ash) in solution

Salts and Salt Solutions

Sodium chloride (table salt) solutions at any concentration
Calcium chloride solutions
Potassium permanganate solutions
Ferric chloride solutions
Aluminum sulfate solutions

Other A-Rated Chemicals

Hydrogen peroxide up to 30% concentration
Bleach (sodium hypochlorite) up to 12.5% concentration
Detergents and soaps (aqueous solutions)
Alcohols: Methanol, ethanol, and isopropanol at concentrations up to about 50%
Glycerin and glycols including ethylene glycol and propylene glycol
Urea solutions including diesel exhaust fluid (DEF)
Water (obviously) - deionized, distilled, potable, and process water

Chemicals with Limited Compatibility (Rating B or C)

These chemicals can be stored in HDPE IBCs under specific conditions, but caution is required:

Rating B - Good but Monitor

Nitric acid above 50% - Increasing concentration reduces compatibility. At 70%, HDPE shows noticeable degradation over extended periods.
Sulfuric acid between 70% and 90% - Still functional but accelerated aging occurs.
Alcohols above 50% concentration - Higher alcohol concentrations begin to swell HDPE slightly.
Hydrogen peroxide between 30% and 50% - The oxidizing nature becomes more aggressive at higher concentrations.
Formaldehyde solutions up to 40% - Long-term storage may cause minor swelling.
Acetic acid above 50% - Glacial acetic acid approaches a C rating.

Rating C - Use with Caution, Short-Term Only

Sulfuric acid above 90% - At concentrated levels, sulfuric acid attacks HDPE more aggressively. Oleum (fuming sulfuric acid) is a definite D rating.
Nitric acid above 70% - Strong oxidizing attack on the polymer chain.
Chromic acid - The strong oxidizing nature makes it incompatible for long-term storage.
Glacial acetic acid (99%+) - Causes measurable swelling and softening.
Gasoline and diesel fuel - HDPE absorbs hydrocarbons, causing swelling and eventual structural weakening. Short-term storage may be acceptable, but these are not ideal long-term storage solutions for petroleum fuels in HDPE.

Chemicals That Should NEVER Go in HDPE IBCs (Rating D)

These substances will damage, dissolve, or permeate through HDPE and must never be stored in standard IBC totes:

Aromatic and Halogenated Solvents

Benzene - Rapidly absorbed by HDPE, causing severe swelling and loss of structural integrity.
Toluene - Similar to benzene, causes rapid swelling and softening.
Xylene - Aggressive solvent action on HDPE.
Chloroform - Penetrates and swells HDPE within hours.
Carbon tetrachloride - Rapidly destroys HDPE.
Methylene chloride (dichloromethane) - One of the most aggressive solvents for HDPE.
Trichloroethylene - Severe swelling and structural failure.

Strong Oxidizers

Oleum (fuming sulfuric acid) - Burns through HDPE.
Chlorine gas (dissolved at high concentrations) - Oxidizes and embrittles the polymer.
Concentrated hydrogen peroxide above 50% - The oxidizing power overwhelms HDPE's resistance.
Bromine - Aggressively attacks HDPE.

Other Incompatible Substances

Essential oils and terpenes - Many natural oils including d-limonene (citrus oil), turpentine, and pine oil are surprisingly aggressive solvents for HDPE. They cause swelling, stress cracking, and permeation.
Ketones: Acetone and methyl ethyl ketone (MEK) cause significant swelling and should not be stored long-term in HDPE.
Esters: Ethyl acetate and similar esters attack HDPE.
Tetrahydrofuran (THF) - Severe compatibility issues.

Temperature Effects on Compatibility

Temperature is one of the most important variables in chemical compatibility. As a general rule, compatibility decreases as temperature increases. A chemical rated A at room temperature might become a B or even C rating at elevated temperatures. Specific considerations include:

Below 68°F (20°C): Most chemicals are at their best compatibility with HDPE. Cold temperatures slow chemical reactions and reduce the rate of diffusion into the polymer.
68°F to 120°F (20°C to 49°C): This is the standard range for most compatibility data. Ratings published in compatibility charts assume this temperature range.
120°F to 150°F (49°C to 66°C): Many B-rated chemicals become C-rated. A-rated chemicals may show minor effects. The maximum continuous service temperature for HDPE is generally considered to be 150°F, above which the material begins to soften and lose structural integrity regardless of the chemical stored.
Above 150°F (66°C): HDPE begins to deform under its own weight. Do not store any liquid above this temperature in a standard HDPE IBC.

In Minnesota, outdoor storage temperatures can swing from well below zero in winter to above 90°F in summer. These thermal cycles themselves stress HDPE and should be factored into your storage decisions for chemically aggressive products.

Concentration Factors

The concentration of a chemical in solution dramatically affects compatibility. Most acids, for example, are rated A or B at dilute concentrations but become problematic as concentration increases. This is because at higher concentrations, more chemical molecules are in direct contact with the HDPE surface, increasing the rate of chemical attack.

Key examples of concentration-dependent compatibility:

Sulfuric acid: A-rated below 70%, B-rated from 70% to 90%, C-rated from 90% to 98%, and D-rated at fuming concentrations.
Nitric acid: A-rated below 50%, B-rated from 50% to 70%, C-rated above 70%.
Hydrogen peroxide: A-rated below 30%, B-rated from 30% to 50%, D-rated above 50%.
Alcohols: A-rated below 50%, B-rated above 50% in most cases.

When in doubt about a specific concentration, always test or consult the manufacturer.

UN Rating Requirements for Hazardous Materials

If you are storing or transporting hazardous materials in IBC totes, the container must carry the appropriate United Nations performance rating. The UN marking on an IBC provides critical information:

Container type: 31H1 denotes a rigid HDPE IBC with a steel cage (the most common type).
Performance level: X, Y, or Z. X-rated containers are approved for the most hazardous materials (Packing Groups I, II, and III). Y-rated containers are approved for Packing Groups II and III. Z-rated containers are for Packing Group III (least hazardous) only.
Specific gravity rating: The maximum specific gravity of the contents for which the container is rated. This is typically 1.2, 1.5, or 1.9.
Hydraulic test pressure: The internal pressure the container can withstand, relevant for materials that generate vapor pressure.
Year of manufacture: Important because HDPE degrades over time. Many regulations limit the use of IBCs for hazardous materials to containers that are within a certain age, typically five years for UN-rated performance.

Transporting hazardous materials in an IBC that does not carry the appropriate UN rating is a violation of DOT regulations (49 CFR) and can result in significant fines and liability.

Testing Procedures for Unknown Compatibility

If you need to store a chemical or chemical mixture that is not listed in standard compatibility charts, testing is essential. Here is a basic testing protocol:

Coupon testing: Obtain a sample of HDPE from the same manufacturer and grade as the IBC bottle. Cut it into small test coupons. Weigh and measure each coupon precisely.
Immersion test: Submerge the coupons in the chemical at the intended storage temperature. Test at multiple time intervals: 24 hours, 7 days, 30 days, and 90 days.
Evaluation: After each interval, remove a coupon, wipe it dry, and measure the weight change (indicates absorption or chemical attack) and dimensional change (indicates swelling). Also assess visual changes: discoloration, softening, cracking, or surface roughness.
Acceptance criteria: A weight change of less than 3% and a dimensional change of less than 2% after 30 days of immersion generally indicates acceptable compatibility for storage applications.

Practical Recommendations

Based on years of experience in the IBC industry, here are our practical recommendations for chemical compatibility:

Always request a material safety data sheet (SDS) for the product you intend to store and review the recommended container materials section.
When buying used IBCs for chemical storage, know what the tote previously held. Residual chemicals from a previous use can interact with your product.
For chemicals in the B or C compatibility range, consider using a lined IBC. Fluorinated HDPE bottles or IBCs with an inner bag or liner made from compatible materials can extend the range of chemicals that can be safely stored.
Label every IBC clearly with its current contents, the date filled, and any hazard information. This protects everyone who handles the container.
When in doubt, do not guess. Contact us or your chemical supplier for guidance. The cost of a compatibility consultation is trivial compared to the cost of a spill, a worker injury, or an environmental cleanup.