n-Hexane Storage & Tank Compatibility

Storing n-Hexane? Start Here

n-Hexane (CAS 110-54-3, formula C₆H₁₄) is a colorless, highly volatile aliphatic hydrocarbon solvent. It is widely used to extract vegetable and seed oils, as a carrier solvent in adhesives, inks, and coatings, and as a cleaning and degreasing solvent. Two facts dominate any storage decision: it is highly flammable (flash point near -23 °C, far below room temperature, so the vapor space is ignitable at ordinary temperatures) and it is a non-polar solvent that attacks polyethylene.

Because of its low flash point and the well-documented neurotoxicity of its metabolite, n-hexane is handled as a flammable, target-organ-toxic liquid. The correct storage system is metal (steel or stainless) or hydrocarbon-resistant FRP - not a standard poly tank. Use the material guidance below, then talk to our fabrication team about a code-compliant vessel.

Why n-Hexane Does Not Belong in a Poly Tank

Polyethylene - both HDPE and cross-linked XLPE - is a non-polar plastic, and so is n-hexane. "Like dissolves like": the solvent molecules diffuse into the polymer matrix, causing the wall to swell, soften, lose mechanical strength, and permeate. Resin-manufacturer chemical-resistance charts rate hexane as U (Unsatisfactory) for HDPE at both ambient and elevated temperature. Cross-linking the polyethylene (XLPE) improves stress-crack resistance but does not stop hydrocarbon uptake, so XLPE is no better here.

The failure mode is not always a dramatic rupture - it is slow permeation (solvent loss and vapor migration through an intact wall), dimensional change at fittings and welds, and progressive loss of wall integrity. For a flammable solvent, permeation through the wall is also a fire-and-vapor hazard, not just a containment problem. Do not store n-hexane in a stock polyethylene tank. Move to steel, stainless, or a properly specified FRP vessel.

Material compatibility at a glance

n-Hexane is a non-polar aliphatic hydrocarbon solvent and is NOT suitable for polyethylene (HDPE or XLPE) tanks - it permeates and swells the wall over time. Store it in carbon steel (UL 142 for flammable service) or 304/316 stainless steel, with fluoropolymer seals and proper bonding and grounding for static control. FRP is an option only with a hydrocarbon-resistant resin and barrier veil. This is a custom-fabrication, not a stock poly-tank, application.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

Flammability. n-Hexane vapor forms explosive mixtures with air (roughly 1.1 to 7.5 percent by volume). Keep all ignition sources away, use intrinsically safe / classified electrical equipment, and bond and ground all tanks, lines, and transfer equipment to dissipate static - a low-conductivity hydrocarbon can accumulate a static charge during transfer. Provide adequate ventilation and consider inert-gas blanketing for large volumes.

Neurotoxicity. n-Hexane is uniquely toxic to the peripheral nervous system. It is metabolized to 2,5-hexanedione, which disrupts axonal transport and causes a progressive distal peripheral neuropathy after months of overexposure - documented in shoe-manufacturing, laminating, spray-painting, and furniture-finishing workers. Control vapor exposure (NIOSH/OSHA limits apply), use proper respiratory protection where engineering controls are insufficient, and avoid skin contact.

General. May be fatal if aspirated (H304); causes skin and eye irritation; suspected reproductive hazard. Store away from strong oxidizers. Have spill control and fire suppression rated for flammable liquids on hand. Always consult the current Safety Data Sheet for the specific product.

Common questions

Can I store n-hexane in a polyethylene (HDPE or XLPE) tank?

No. n-Hexane is a non-polar aliphatic hydrocarbon that permeates and swells polyethylene. Resin-resistance charts rate hexane as Unsatisfactory (U) for HDPE, and cross-linking (XLPE) does not solve the problem. The wall softens, swells, loses strength, and lets solvent permeate through. Use steel, stainless, or hydrocarbon-resistant FRP instead.

What is the right tank material for n-hexane?

Carbon steel (commonly UL 142 aboveground tanks for flammable service) or 304/316 stainless steel, with fluoropolymer (PTFE/PVDF) seals and Buna-N or Viton elastomers. FRP is acceptable only with a hydrocarbon-resistant resin and a solvent barrier veil. All metal systems must be bonded and grounded for static control.

Why is bonding and grounding so important for hexane?

n-Hexane has very low electrical conductivity, so it can build up a static charge during pumping and free-fall filling. With a flash point near -23 °C, the vapor space is ignitable at room temperature, so a static spark can ignite it. Bonding and grounding every tank, line, and transfer point dissipates that charge safely.

Is n-hexane more dangerous than other hydrocarbon solvents?

It shares the high flammability of heptane, pentane, and naphthas, but n-hexane has a specific, well-documented neurotoxicity: its metabolite 2,5-hexanedione causes peripheral neuropathy with prolonged overexposure. Many operations substitute heptane or other isomers to reduce that nerve-damage risk while keeping similar solvent behavior.

Does UL 142 apply to a hexane tank?

Yes - UL 142 is the standard for steel aboveground tanks for flammable and combustible liquids, and n-hexane is a flammable liquid. A UL 142 carbon-steel tank (or a stainless equivalent) is a common, code-aligned choice for aboveground hexane storage. Our fabrication team can quote a vessel built to your volume and site requirements.