Iodic Acid Storage & Tank Compatibility

Storing Iodic Acid? Start Here

Iodic acid (_HIO3) is a white crystalline solid and one of the few stable, isolable oxyacids of iodine. With a pKa near 0.75 it behaves as a fairly strong acid, and the iodine center in the +5 oxidation state makes it an energetic oxidizer as well. It is highly water soluble, dissolving to roughly 269 grams per 100 milliliters at room temperature, and on heating past about 110 C it dehydrates toward iodine pentoxide rather than boiling. Industrially it appears in analytical chemistry, iodometric standardization, oxidation reactions, and specialty iodine processing. Because it pairs corrosivity with oxidizing power, storage and transfer decisions hinge on materials that resist both attack modes at once. Commodity polyethylene tanks rated for many mineral acids are not a safe default here; the sections below set out an honest compatibility picture and the safety controls the chemistry demands.

Is Iodic Acid Compatible With Polyethylene (HDPE / XLPE) Tanks?

Honestly, no - polyethylene is not the right choice for iodic acid. While HDPE and crosslinked polyethylene handle many non-oxidizing mineral and organic acids very well, iodic acid is an active oxidizing acid. Strong oxidizers progressively attack the polyethylene backbone, causing surface degradation, stress cracking, and embrittlement; the effect accelerates with higher concentration and temperature. Very dilute, cool, short-contact solutions may be tolerated in polypropylene for incidental service, but for concentrated solutions, warm process streams, or long-term bulk storage we rate HDPE/XLPE as Unsuitable. Specify fluoropolymer (PVDF or PTFE), oxidizer-grade vinyl ester FRP with a corrosion barrier, or glass/glass-lined equipment instead, and always validate the specific concentration, temperature, and elastomer selections against a current chemical resistance chart before committing a vessel.

Material compatibility at a glance

Iodic acid is both a strong acid and an active oxidizer, a combination that is hard on commodity plastics and most metals. Polyethylene (HDPE/XLPE) is not recommended for concentrated or warm iodic acid; specify fluoropolymers (PVDF, PTFE), oxidizer-grade vinyl ester FRP, or glass-lined equipment for primary containment, and confirm gasket and fitting materials separately.

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 as a strong oxidizer: keep away from combustibles, reducing agents, organics, and metal powders - contact can intensify or initiate fire (H272).
• It causes severe skin burns and eye damage (H314); wear acid-resistant gloves, goggles or a face shield, and chemical-resistant clothing.
• Harmful if swallowed and may damage organs (H302, H371); never pipette by mouth and avoid mist or dust inhalation.
• Store in tightly closed, oxidizer-compatible containers, segregated from acids' incompatibles, fuels, and combustible packaging.
• Provide eyewash and safety shower access; have spill control rated for oxidizing acids on hand.
• Verify tank, gasket, valve, and fitting materials against a current resistance chart for the exact concentration and temperature before use.

Common questions

Can I store iodic acid in a standard HDPE or poly tank?

No. Iodic acid is a strong oxidizing acid, and oxidizers degrade polyethylene over time. For concentrated or warm service it is rated Unsuitable for HDPE/XLPE; use PVDF, PTFE, oxidizer-grade vinyl ester FRP, or glass-lined equipment instead.

What is the NFPA 704 rating for iodic acid?

It is rated 3-0-1 with an OX special notice: health 3 (corrosive), flammability 0 (non-combustible solid), instability 1 (stable but a reactive oxidizer), and OX indicating an oxidizing agent.

Is iodic acid flammable?

No. Iodic acid is a non-combustible solid with no flash point. The hazard is the opposite - as an oxidizer it can intensify or start fires in nearby combustible or reducing materials (H272).

What materials resist iodic acid best?

Fluoropolymers such as PVDF and PTFE, glass and borosilicate, and oxidizer-grade vinyl ester FRP with a corrosion barrier perform best. Most metals, including 316 stainless steel, are attacked because of the combined acidity and halide-oxidizer action.