Acrylonitrile Storage & Tank Compatibility

Storing Acrylonitrile? Start Here

Acrylonitrile (CAS 107-13-1, · C₃H₃N · also called vinyl cyanide or 2-propenenitrile) is a clear, colorless, highly flammable liquid monomer used to make acrylic fibers, ABS and SAN resins, nitrile rubber, and adiponitrile. It is one of the more hazardous commodity chemicals you can be asked to store: it is acutely toxic by every route (it releases cyanide in the body and is readily absorbed through intact skin), it is a recognized carcinogen, and it can polymerize violently if its inhibitor is depleted or it contacts the wrong material.

From a tank standpoint the headline is simple: acrylonitrile is not a polyethylene chemical. As a polar, reactive solvent-monomer it swells, softens, stress-cracks, and permeates polyethylene and most other thermoplastics. Bulk acrylonitrile is stored in carbon steel or stainless steel with a nitrogen blanket, temperature control, and a polymerization inhibitor — not in a poly tank. This page summarizes the verified identity, hazards, and the correct materials of construction so you can specify storage that is actually safe.

Why Polyethylene Tanks Are Not Suitable for Acrylonitrile

Rotationally molded HDPE and crosslinked (XLPE) tanks are excellent for water, brines, and many aqueous acids and bases. Acrylonitrile is a different class of chemical entirely. It is a low-molecular-weight, polar, unsaturated monomer that behaves as an aggressive organic solvent toward polyolefins. In contact with polyethylene it is absorbed into the polymer matrix, where it causes swelling, softening, loss of mechanical strength, and environmental stress cracking, while permeating through the wall. There is no inhibitor or liner trick that turns a standard poly tank into an appropriate acrylonitrile vessel.

On top of the permeation problem, acrylonitrile carries a serious polymerization-runaway hazard: it can polymerize spontaneously in a container — especially in the absence of oxygen, on light exposure, or if its inhibitor is consumed — and a runaway can rupture the vessel violently. Safe storage depends on a controllable steel system (inert gas blanket, temperature monitoring, inhibitor management, peroxide testing), which is engineered around metal tanks, not poly. For these reasons we rate polyethylene, polypropylene, and PVC/CPVC as Not Recommended (U) for acrylonitrile and direct this product to custom steel or stainless fabrication.

Get the right tank built: explore our certified steel fabrication, compare alloys on 304 vs 316 stainless, and weigh the trade-offs in FRP vs steel vs poly. To scope an acrylonitrile build with inhibitor, nitrogen-blanket, and temperature-control provisions, call 866-418-1777.

Material compatibility at a glance

Acrylonitrile is a flammable, acutely toxic, carcinogenic reactive monomer with a real polymerization-runaway hazard. It attacks and permeates polyethylene and most thermoplastics, so rotomolded poly tanks are NOT suitable. The industry-standard storage solution is carbon steel or 304/316 stainless steel, fitted with a nitrogen blanket, temperature control, and the manufacturer's polymerization inhibitor (such as MEHQ). Copper/copper alloys, strong acids, strong bases, and oxidizers must be excluded from all wetted surfaces.

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

Acrylonitrile is among the most dangerous chemicals on this site — treat it accordingly. It is a recognized carcinogen: IARC classifies it as Group 2B (possibly carcinogenic to humans), the U.S. National Toxicology Program lists it as reasonably anticipated to be a human carcinogen, and the U.S. EPA classifies it as a probable human carcinogen (Group B1). It is also acutely toxic — fatal if inhaled, fatal in contact with skin, and toxic if swallowed — and it releases cyanide in the body, so poisoning can include headache, dizziness, dyspnea, lactic acidosis, and cardiovascular collapse, sometimes with delayed onset (4–12 hours).

Engineering and PPE: store under a nitrogen blanket with temperature control and the manufacturer-supplied polymerization inhibitor (MEHQ); test for peroxide accumulation, which signals inhibitor depletion. Keep acrylonitrile far from strong acids, strong bases, oxidizers (especially bromine), amines, and all copper/copper alloys. Eliminate ignition sources (flash point ~32 °F) and provide adequate ventilation and bonding/grounding. Use butyl elastomer gloves rather than latex or cotton, full chemical splash protection, and supplied-air respiratory protection per the SDS. Always follow the manufacturer's Safety Data Sheet, OSHA's acrylonitrile standard (29 CFR 1910.1045), and local fire code — this page is general guidance, not a substitute for the SDS or a qualified engineer.

Common questions

Can I store acrylonitrile in a polyethylene tank?

No. Acrylonitrile is a polar, reactive monomer that swells, softens, stress-cracks, and permeates polyethylene (HDPE and XLPE) as well as polypropylene and PVC. There is no liner or inhibitor that makes a standard poly tank safe for it. Bulk acrylonitrile belongs in carbon steel or stainless steel.

What is the correct tank material for acrylonitrile?

The industry standard is carbon steel or 304/316 stainless steel, equipped with a nitrogen blanket, temperature control, and the manufacturer's polymerization inhibitor (such as MEHQ). 316 stainless adds margin where higher purity or longer life is needed. Avoid copper and copper alloys, galvanized/zinc surfaces, and any contact with strong acids, bases, or oxidizers.

Why is acrylonitrile considered so hazardous?

It is a recognized carcinogen (IARC Group 2B, NTP listed, EPA probable human carcinogen B1) and acutely toxic by inhalation, skin contact, and ingestion — it releases cyanide in the body and is readily absorbed through intact skin. It is also highly flammable (flash point near 32 °F) and can polymerize violently if its inhibitor is depleted, potentially rupturing a container.

What materials and chemicals are incompatible with acrylonitrile?

Avoid copper and copper alloys (brass, bronze), strong acids, strong bases/alkalies, amines, and strong oxidizers — especially bromine. Strong acids or bases can trigger runaway polymerization, and heating or fire produces toxic hydrogen cyanide gas. Keep it segregated from oxidizers and ignition sources, and qualify all elastomer seals before use.

Do you sell a stock acrylonitrile tank?

We do not list a stock poly tank for acrylonitrile because polyethylene is not suitable. We handle acrylonitrile storage through custom carbon steel or stainless fabrication engineered for the inhibitor/nitrogen-blanket/temperature-control system this monomer requires. Call 866-418-1777 to scope a build.