Cyclohexane Storage & Tank Compatibility

Storing Cyclohexane? Start Here

Cyclohexane (CAS 110-82-7, PubChem CID 8078, C₆H₁₂) is a colorless, highly flammable aliphatic cyclic hydrocarbon used as a solvent and as a feedstock for nylon intermediates. With a flash point near -20 °C (-4 °F) and a flammability rating of NFPA 3, its vapor forms an ignitable mixture with air at ordinary temperatures, so static control, bonding, grounding, and proper venting are central to safe storage.

As a non-polar solvent, cyclohexane is aggressive toward common plastic tank materials. It readily permeates and swells polyethylene and polypropylene, so the standard rotomolded poly tanks used for water and many aqueous chemicals are not suitable. Bulk cyclohexane belongs in steel, stainless, fluoropolymer-lined, or properly specified FRP equipment.

Why Polyethylene Tanks Are Not Suitable for Cyclohexane

Polyethylene tanks (XLPE and HDPE) perform well with water and many aqueous chemicals because those fluids are polar and do not dissolve into the polymer. Cyclohexane is the opposite case: it is a non-polar hydrocarbon with strong chemical affinity for the polyethylene backbone. In contact with the tank wall it is absorbed into the polymer, causing the material to swell, soften, and gain weight.

The practical consequences are progressive and serious: dimensional change and wall softening, permeation of solvent and vapor through the wall, reduced burst and impact strength, and environmental stress cracking at fittings and welds. None of this is reversible, and it worsens with temperature and time. For these reasons we do not recommend or supply polyethylene tanks for cyclohexane service. The same caution applies to polypropylene. The correct path is steel, stainless, fluoropolymer lining, or a fabricator-confirmed hydrocarbon-resistant FRP build.

Material compatibility at a glance

Cyclohexane is a flammable, non-polar aliphatic hydrocarbon solvent. The correct materials of construction are carbon steel or stainless steel (electrically bonded and grounded), fluoropolymer linings, or FRP built with a hydrocarbon-resistant resin and barrier veil. Polyethylene and polypropylene tanks are not suitable - the solvent permeates and swells them.

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

Treat cyclohexane as a flammable liquid hazard first. Its flash point is well below room temperature, so ignitable vapor is present during normal handling. Eliminate ignition sources, bond and ground the tank, pumps, hoses, and receiving containers to control static discharge, and use explosion-protected electrical equipment in the storage area. Provide normal and emergency venting and flame arrestors as required by code.

Cyclohexane is an aspiration hazard (H304) - if swallowed and drawn into the lungs it can be fatal, so never siphon by mouth. Vapor can cause drowsiness, dizziness, and respiratory irritation (H335, H336); provide adequate ventilation and respiratory protection per the SDS. It is suspected of reproductive toxicity (H361) and may cause organ effects (H371), and it is very toxic to aquatic life (H410) - design secondary containment to prevent any release to soil or water. Keep cyclohexane away from strong oxidizers. Always follow the manufacturer Safety Data Sheet and applicable fire, building, and environmental codes.

Need a tank built for cyclohexane? Our custom fabrication team builds code-compliant storage to spec. See our UL 142 aboveground steel tanks, 304 vs 316 stainless guidance, and FRP vs steel vs poly comparison, or call 866-418-1777 to spec a system for your application.

Common questions

Can I store cyclohexane in a polyethylene tank?

No. Cyclohexane is a non-polar hydrocarbon solvent that permeates and swells polyethylene (XLPE and HDPE) and polypropylene. The wall softens, gains weight, and can stress-crack, leading to loss of containment. Use carbon steel, stainless steel, fluoropolymer-lined steel, or hydrocarbon-resistant FRP instead.

What is the correct tank material for cyclohexane?

Carbon steel or stainless steel are the recommended primary options, electrically bonded and grounded for static control. Fluoropolymer (PTFE/PVDF/PFA) linings are excellent where contamination control matters. FRP is acceptable only when built with a hydrocarbon-resistant resin and a chemical barrier veil confirmed by the fabricator.

Is cyclohexane flammable?

Yes - highly flammable (GHS H225, NFPA flammability 3). Its flash point is about -20 °C (-4 °F), so its vapor forms an ignitable mixture with air at ordinary temperatures. Control ignition sources, bond and ground all equipment, and provide proper venting and flame arrestors.

What is the NFPA 704 rating for cyclohexane?

Per NOAA CAMEO Chemicals, cyclohexane is Health 1, Flammability 3, Instability 0, with no special hazard symbol. The driver is flammability, not reactivity - it is normally stable but ignites readily.

Does cyclohexane need secondary containment?

Yes. Cyclohexane is a flammable liquid and is very toxic to aquatic life (H410). Provide secondary containment sized to code, locate away from drains and waterways, and follow your SDS and local fire and environmental regulations to prevent any release.