HPX-Ta™ rupture disc: tantalum version for highly corrosive media

In short: the HPX-Ta™ is the tantalum version of the HPX® disc: the same idea of a semicircular, scored, reverse-acting dome, but made entirely of that metal. It exists for processes in which stainless steel and nickel alloys do not last, such as those handling halogens and strong acids.

How it works

Mechanically it behaves like any reverse-acting disc: the dome receives pressure on its convex face, remains stable while the load is below the burst value and, on reaching it, reverses and opens along the score line. The difference is in the material. Tantalum forms a very stable surface oxide film that protects it against many acids and oxidizing agents, even hot and concentrated ones; for this reason it is considered one of the most corrosion-resistant metals used in process equipment.

A point that is sometimes overlooked: protecting only the disc is not enough if the disc holder is exposed to the same fluid. For that reason the manufacturer offers HPX disc holders with a tantalum lining or coating on the wetted surfaces, so that the whole assembly resists the medium and not just the membrane.

When it makes sense (and when it does not)

• Suitable with bromine, chlorine, hydrochloric acid, nitric acid, sulfuric acid and other highly corrosive fluids, which are the applications the manufacturer mentions.
• Suitable when, in addition to the aggressive fluid, there is elevated temperature or a very humid environment, conditions that accelerate corrosion of other metals.
• Suitable if discs of other materials fail early because of thinning or pitting.
• Not suitable as a «just in case» option in services where stainless steel or a nickel alloy is sufficient: tantalum is a high-cost material.
• Check compatibility case by case. In general terms, tantalum is not suitable against hydrofluoric acid, fluorides, or hot strong bases; if your process contains them, consult the supplier.

Data to specify it

• Complete fluid composition, including contaminants or traces, with concentrations.
• Maximum temperature and required burst pressure at that temperature.
• Operating pressure and regime (steady or cycling).
• Nominal diameter and whether the disc holder must be lined or coated with tantalum.
• Material of the gaskets that will be in contact with the process.

To learn more: Materials for rupture discs and Installation and disc holders.

Descriptive sheet for educational purposes. For availability and a quote for this model, consult P&V Control Devices.