Image of rupture disc.
Exemplary representation. Not to scale.

Rupture discs protect the plant in case of faulty operating states against the occurrence of critically high pressure values which would exceed the design pressure of components of the plant. If a certain pressure is reached, the rupture disc breaks open to release medium from the affected plant volume in order to prevent a further increase of the pressure. Rupture discs are commonly installed at the highest point of the protected volume so that the hydrostatic pressure needs to be considered when defining the design pressure of components located further below. For the fabrication of rupture discs, the conformity assessment procedures according to category IV of the pressure equipment directive 2014/68/EU are applied.

Rupture discs provide a high discharge capacity at comparably little effort. A disadvantage compared to the application of safety vales is, that in the case of a pressure relief event the broken rupture disc must be replaced and, additionally, the affected plant section is left open towards the discharge side of the rupture disc. The section of the plant, or even the entire plant, cannot be further operated until the installation of a new rupture disc and there is a risk of contamination by the ingress of ambient media via the broken rupture disc.

The potential of the medium being in either the gaseous as well as the solid state at the inlet of the rupture disc in case of a pressure relief event necessitates the discharge capacity to be determined for both states, as it differs for different densities of the released medium.

Set Pressure

The pressure at which a rupture disc breaks open is called the set pressure. It is important to note that this value refers to the actual pressure difference between the inlet and the outlet side of the rupture disc. Therefore, not only the pressure within the protected plant volume are considered, when defining the set pressure, but also the given pressure on the outlet side of the rupture disc.

Inlet- and Outlet-Pipes

In case of a pressure relief event, when a rupture disc breaks open, pressure losses occur via the inlet- and outlet pipes. These pressure losses have an impact on the process conditions at the rupture disc and are considered for the sizing in order to ensure that the required discharge capacity will be reached.