Adiponitrile Storage & Tank Compatibility

Storing Adiponitrile? Start Here

Adiponitrile (hexanedinitrile, C₆H₈N₂) is a colorless to light-yellow liquid dinitrile best known as the precursor to hexamethylenediamine and nylon-6,6. It is a moderately polar, high-boiling organic solvent that is fairly soluble in water yet miscible with most organic liquids. Although its very low vapor pressure makes it less volatile than light solvents, adiponitrile is acutely toxic by inhalation, skin contact and ingestion, and it can liberate cyanide-type metabolites in the body, so closed handling is essential. For storage and containment the controlling fact is that the neat liquid behaves like an organic solvent toward thermoplastics: it swells and softens polyethylene over time. That makes material selection, not just toxicity control, the central engineering decision for any vessel holding the concentrated product.

Is Polyethylene (HDPE / XLPE) Safe for Adiponitrile?

Honest answer: no, not for the neat liquid. Polyethylene tanks excel at aqueous salts, acids, bases, glycols, alcohols, amines and surfactants, but they are not recommended for concentrated organic solvents - and adiponitrile is a polar aprotic nitrile solvent. General polyethylene resistance charts rate organic nitriles, ketones, esters and aromatic solvents as not recommended because they are absorbed into the polymer, causing swelling, softening, loss of wall strength and eventual permeation. The same charts show HDPE and XLPE as fully resistant to water-based chemistries, which is why dilute aqueous adiponitrile waste streams may be tolerable after dedicated compatibility testing at the actual concentration and temperature. For bulk storage of the product itself, specify 316/316L stainless steel or fluoropolymer-lined steel with PTFE/PFA seals; reserve polyethylene only for verified low-concentration aqueous service.

Material compatibility at a glance

Neat adiponitrile is an aggressive polar aprotic organic nitrile solvent. Polyethylene (HDPE and XLPE) and polypropylene are NOT recommended for the concentrated liquid because the solvent swells and softens the polymer over time. Store and handle in 316/316L stainless steel or fluoropolymer-lined equipment, with PTFE/PFA/FEP or verified FKM seals. Keep dry and away from heat; carbon steel is used industrially for the dry product but corrodes with moisture or acidic decomposition.

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

• Acutely toxic - fatal if inhaled and toxic by skin contact or ingestion (H330, H311, H301); handle only in closed systems with local exhaust ventilation and treat as a cyanide-releasing hazard.
• Use chemical-resistant gloves, splash goggles or face shield, and a supplied-air or appropriate respirator; have cyanide antidote protocols and trained responders available where bulk quantities are handled.
• Combustible liquid (flash point 199 F) - keep away from heat, sparks and open flame; ground and bond during transfer and avoid generating mists or vapors at elevated temperature.
• Keep separated from strong oxidizers, strong acids, strong bases and strong reducing agents, which can cause violent or hazardous reactions.
• Store in tightly closed 316 stainless or fluoropolymer-lined vessels in a cool, dry, well-ventilated area with secondary containment; keep dry to limit hydrolysis and corrosion.
• Provide eyewash and safety shower; collect spills with non-combustible absorbent and prevent entry to drains and waterways.

Common questions

Can I store adiponitrile in an HDPE or XLPE poly tank?

Not for the concentrated liquid. Neat adiponitrile is an organic nitrile solvent that swells and softens polyethylene over time, so HDPE and XLPE are rated U (not recommended). Use 316/316L stainless steel or a fluoropolymer-lined vessel. Only dilute aqueous adiponitrile streams might be acceptable, and only after compatibility testing at your real concentration and temperature.

What is the NFPA 704 rating for adiponitrile?

Per CAMEO Chemicals, adiponitrile is Health 3, Flammability 2, Instability 1, with no special hazard symbol. The Health 3 reflects its acute toxicity, the Flammability 2 its combustible-liquid behavior (flash point about 199 F), and the Instability 1 indicates it is normally stable but can react under heat or with incompatible chemicals.

Why is adiponitrile so toxic if it has such a low vapor pressure?

Adiponitrile barely evaporates at room temperature, but toxicity is driven by the molecule itself. As a dinitrile it can be metabolized to release cyanide, making it fatal by inhalation of mist or heated vapor and toxic by skin absorption and ingestion. Low volatility reduces routine vapor exposure but does not lower the intrinsic hazard, so closed handling and skin protection remain mandatory.

Which materials are best for adiponitrile storage and seals?

Choose 316/316L stainless steel for the tank and piping, with PTFE, PFA or FEP linings and gaskets. Glass and borosilicate are inert for sight glasses. Avoid polyethylene, polypropylene and EPDM with the neat liquid. Carbon steel can hold dry product but corrodes with moisture or acidic decomposition, so keep the system dry and monitored.