Tantalum behaves somewhat like glass when it comes to hot concentrated acid. The logic behind this is similar because a very dense oxide layer that heals itself is formed and serves to protect tantalum from hydrochloric, nitric, and sulfuric acid, even at much higher concentrations and temperatures where Hastelloy and zirconium do not survive. Few other metals can do this. At USA Piping Solution, customers can find tantalum pipes and tubes made of pure tantalum according to UN R05400 and ASTM B521 specifications.Where a lower-cost near-substitute will do, our Niobium Pipes & Tubes page covers tantalum's sister metal.
Why Tantalum Is Specified When Nickel Alloys Fail
There is a rung on the corrosion ladder above even the best nickel alloys, and tantalum owns it. In hot concentrated hydrochloric, sulfuric, and nitric acid, and in most acid mixtures short of hydrofluoric acid and fuming sulfuric acid, tantalum behaves as though it were chemically inert, because the tantalum pentoxide film that forms on its surface is one of the most stable oxides in chemistry. Where a Hastelloy tube would eventually thin and fail, a tantalum tube simply continues. That is the entire economic case for a metal this expensive: in the worst acid service, it is often the only material that lasts, and a tantalum lining or bayonet heater outlives every alternative by a wide enough margin to justify the cost.
THE ONE EXCEPTION: Tantalum is attacked by hydrofluoric acid, fuming sulfuric acid (oleum), and strong hot alkalis, because these break down the protective oxide film. It is not a universal material; it is a specialist for oxidizing and non-oxidizing acids. Tell us the exact chemistry and temperature and we will confirm whether tantalum is the right specification or whether zirconium or a nickel alloy fits better.
Where the corrosion duty falls short of tantalum's territory, our Niobium Pipes & Tubes page covers the lower-cost, lower-density alternative metal.
Specifications
| Grade | UNS R05400, unalloyed tantalum (powder-metallurgy consolidation) |
| Standard | ASTM B521, Tantalum and Tantalum Alloy Seamless and Welded Tubes |
| Construction | Seamless (any seamless method) and welded (fusion welded from flat-rolled product, no filler metal) |
| Other Grades to Order | R05200 (vacuum melted unalloyed), R05252 (Ta-2.5W), R05255 (Ta-10W) available on request |
| Typical OD Range | Approximately 6 – 150 mm; capillary sizes below 5 mm OD available |
| Typical Wall Range | Approximately 0.2 – 5.0 mm |
| Melting Point | 3017°C (5463°F), among the highest of all metals |
Dimensional ranges are typical of what is supplied to this standard rather than limits set by it. Send your OD, wall, and length and we will confirm availability, since tantalum is made to order rather than held in deep stock.
Applications
- Acid Process Equipment: bayonet heaters, coils, thermowells, and spargers in hot hydrochloric, sulfuric, and nitric acid service.
- Heat Exchanger Tubes: in the most aggressive acid heat-transfer duties, where tantalum tube outlasts every alternative.
- Chemical & Pharmaceutical Reactors: linings and internals where product purity and material survival both matter.
- Instrumentation & Thermowells: protecting sensors in acid streams.
- Corrosion-Critical Repairs: tantalum patch and sleeve repairs to glass-lined and other equipment.
Testing, Certification & Availability
Tube is supplied to ASTM B521 with mill certification and traceability, with the standard's tensile, flare, and reverse-flattening tests performed; see our Quality Policy page for the wider program. Because tantalum is a made-to-order refractory metal, send the full requirement, grade, OD, wall, length, quantity, and the service chemistry, for an accurate quote and lead time.
Related Products
Frequently Asked Questions
What acids can tantalum handle that Hastelloy cannot?
Hot concentrated hydrochloric, sulfuric, and nitric acid, and most acid mixtures, at temperatures and concentrations where nickel alloys corrode. The exceptions are hydrofluoric acid, oleum, and strong hot alkalis, which attack tantalum's protective film. For those, tantalum is the wrong choice; for almost everything else acidic, it is close to inert.
Is R05400 the same as R05200?
Both are unalloyed tantalum; the difference is how they are consolidated. R05400 is powder-metallurgy consolidated, R05200 is vacuum melted. Both are covered by ASTM B521. We can supply either; state which your specification calls for.
Why is tantalum tube so expensive, and when is it worth it?
Tantalum is a rare refractory metal and costly to process. It is worth it precisely in the acid services where cheaper materials fail fast: when a nickel alloy tube would need frequent replacement, a tantalum tube that lasts for the life of the plant is often the lower total cost.
Do you supply tantalum in seamless and welded?
Yes, both, per ASTM B521. Welded tantalum tube is fusion welded from flat-rolled product with no filler metal and suits thinner walls; seamless suits thicker walls and the most critical service. Tell us which your application needs.