Bursting discs are safety devices that protect systems such as pressure vessels or piping against overpressure or vacuum conditions. Bursting discs are also known as rupture discs or burst discs.
Bursting discs are composed of a thin membrane which is designed to rupture at a predetermined differential pressure and temperature. Bursting discs provide instantaneous pressure relief and act more quickly than pressure relieving valves - within milliseconds the disc bursts to change from fully closed to fully open. Bursting discs are leak-tight until they burst, while pressure relieving valves can leak during operation.
The disadvantage of bursting discs is they must be replaced once the disc has burst. Bursting discs cannot reseal, so they continue to relieve until the downstream pressure equals the system pressure.
Bursting discs can be used as the primary pressure relieving device or as a secondary pressure relieving device when used as a back-up to pressure relieving valves. The purpose of a secondary relieving device is to provide additional protection for an event that would exceed the capacity of the primary relieving device.
Discs are typically made from stainless steel, however they can be manufactured from aluminium, nickel, hastelloy, inconel, monel or other more exotic materials.
There are three main types of bursting discs:
|Forward acting discs – also known as conventional or concave bursting discs. The dome of a forward acting disc faces away from the pressure or flow. Bursting is due to exceeding the tensile strength of the disc material. Forward acting bursting discs have historically been the conventional bursting disc solution|
|Reverse acting discs – also known as convex bursting discs. The dome of a reverse acting disc faces toward the pressure or flow. Bursting is due to exceeding the bending, buckling or shear stress of the disc material. Reverse acting discs allow operating pressures much closer to the predetermined burst pressure (this ratio is known as the operating ratio). As such, industry is increasingly switching to reverse acting discs for many applications.|
|Flat bursting discs are the original bursting disc design. They do not allow for a very high operating ratio and do not offer good control over the burst pressure. Flat burst discs are often manufactured from graphite and are often low cost||
Bursting discs are typically installed in a holder. The holder accurately positions the disc and ensures that the disc bursts at the predetermined bursting pressure and temperature. The holder also protects the dome of the bursting disc during installation. The holder is sufficiently deep, so that the bursting disc dome does not protrude beyond the bursting disc holder
Industry increasingly requires remote indication of a burst disc event. There are a range of sensor technologies available to provide remote indication. The first sensors used were membranes with electrical wires positioned in-line downstream of the disc. The bursting of a disc destroys the membrane, breaks the electrical circuit which indicates a bursting disc event. These sensors Mare fragile and can suffer from reliability issues. As such other mechanically robust and non-invasive sensors are now available including magnetic proximity sensors, inductive sensors, and fibre optical sensors.
Cebeco offers a full range of bursting disc solutions. We are happy to assist you to determine the right solution for your application. Contact us on 02 9651 4220 or email@example.com.