In short: the HPX® is a semicircular, scored, reverse-acting disc designed to work with liquids, gases, or steam. Its main selling point is that it allows a high ratio between operating pressure and burst pressure, which makes it possible to operate close to the limit without shortening the disc's life too much.
How it works
The HPX® is a metal dome installed with the convex face toward the process. Pressure loads it in compression; on reaching the burst value the dome reverses and the metal opens along the semicircular score. The unscored portion remains as a hinge, so the petal folds toward the discharge instead of detaching. The manufacturer stresses that the design aims for full opening, which is what allows the disc to deliver the flow area assumed in the relief calculation.
The key idea of this model is the operating ratio: the quotient between the pressure at which the equipment normally works and the marked burst pressure. The higher that allowable ratio, the closer to the burst point the process can operate without the disc fatiguing or failing prematurely. Conventional (tension-loaded) discs usually call for more margin; reverse-acting ones such as the HPX® tolerate smaller margins. According to the manufacturer, control of material thickness and manufacturing quality is what makes it possible to offer precise burst values.
When it makes sense (and when it does not)
- Suitable when the process usually operates close to the design pressure and capacity should not be sacrificed to leave margin for the disc.
- Recommended for liquid, gas or vapor services with static, cyclic or pulsating operation.
- Suitable as a general-purpose disc in process industries when the fluid is not extremely aggressive.
- It is not the right variant for highly corrosive acids or halogens (the tantalum HPX-Ta™ exists for that) or for hygienic processes (SANITRX HPX® family).
- Caution: in fully liquid service, the energy available to reverse the dome is lower than with gas; confirm with the manufacturer that the selected size and pressure are qualified to open fully on liquid.
Data to specify it
- Burst pressure and coincident temperature.
- Maximum operating pressure, to calculate the actual operating ratio.
- Fluid phase at the time of relief (liquid, gas, vapor, or mixture).
- Material compatible with the fluid.
- Diameter and disc holder; if replacing an existing disc, the model of the installed disc holder.
- Pressure regime: static, cyclic or pulsating.
| Characteristic | According to the manufacturer |
|---|---|
| Type | Semicircular, scored, reverse-acting |
| Fluids | Liquids, gases or steam |
| Maximum recommended operating ratio | 90 % or 95 % of the marked burst pressure |
| Sizes | 1" to 12" (25 to 300 mm) |
| Burst pressure | 10 to 2,000 psig (0.689 to 138 barg) |
| Seat | Flat |
| ASME stamp | Available |
| Service | Static, cyclic or pulsating |
Values published by Continental Disc Corporation at contdisc.com (accessed: October 4, 2026).
To learn more: Relief area calculation according to API 520 and Rupture disc vs. pressure relief valve.
Descriptive sheet for educational purposes. For availability and a quote for this model, consult P&V Control Devices.