Stop Saying "Titanium Flanges Never Rust" – That's the Biggest Misunderstanding About Titanium

In high‑end industrial sectors such as chemical engineering, marine engineering, and nuclear power, titanium flanges are highly valued for their excellent corrosion resistance. However, the claim that "titanium flanges never rust" is becoming a dangerously misleading statement.

Titanium does have impressive corrosion resistance, thanks to a nanoscale titanium dioxide (TiO₂) protective film that forms instantly in air or water. This film, only a few nanometers thick, is extremely effective at isolating corrosive media.
What’s more, the film is self‑healing: even if scratched, it quickly regenerates in the presence of trace oxygen or moisture.

These properties make titanium perform exceptionally well in seawater, chloride environments, and various acidic media – often outperforming stainless steel.
But "corrosion resistant" does not mean "never corrodes".

In hundreds of industrial projects, the most common failure mode of titanium flanges is not general corrosion, but crevice corrosion.

What is crevice corrosion?

When a titanium flange forms tight crevices with gaskets, bolts, or other components, and the environment meets the following conditions, the risk increases significantly:

• Temperature exceeding 75°C

• High‑concentration chloride environment (e.g., seawater, brine)

• Low‑oxygen or stagnant conditions (oxygen cannot be replenished inside the crevice)

Under these conditions, the protective film inside the crevice breaks down, leading to rapid local corrosion – while the flange surface may still appear intact.

Hot reducing acids

In high‑temperature, low‑pH hydrochloric or sulfuric acid, titanium's protective film is destroyed, causing rapid general corrosion. In such cases, titanium may perform worse than certain specialty stainless steels.
For strong reducing acid environments, Ti‑Pd alloy flanges are recommended, as palladium significantly improves crevice corrosion resistance. Alternatively, PTFE‑lined or tantalum‑lined solutions may be used.

Fluoride‑containing media

Hydrofluoric acid (HF) is highly corrosive to titanium. Studies show that Ti‑6Al‑4V alloy undergoes rapid overall corrosion in 0.2% HF solution.
Pure titanium flanges must not be used in fluoride‑containing media.

Dry chlorine and halogen gases

At high temperatures, dry chlorine, bromine, or fluorine gas can destroy titanium's oxide film, leading to catastrophic corrosion.

Hydrogen embrittlement risk

In acidic environments with pH < 2, titanium may absorb hydrogen and cause hydrogen embrittlement (hydride formation), resulting in sudden brittle fracture.

Titanium is a remarkable metal, but not a magical one.
The slogan "never rust" may catch attention, but scientific material selection, rigorous design, and proper installation are the true foundations for making titanium flanges perform at their best.

We provide high‑quality titanium flange products and also wish to build technical‑rational partnerships – applying titanium in the right places, in the right way.