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A rupture disk is a device designed to function by the bursting of a pressure-retaining disk.
This assembly consists of a thin, circular membrane usually made of metal, plastic, or graphite that is firmly clamped in a disk holder. When the process reaches the bursting pressure of the disk, the disk ruptures and releases the pressure
What is a rupture disk?
Rupture disks can be installed alone or in combination with other types of devices. Once blown, rupture disks do not reseat; thus, the entire contents of the upstream process equipment will be vented.
Rupture disks are commonly used in series (upstream) with a Relief valve to prevent corrosive fluids from contacting the metal parts of the valve. In addition, this combination is a reclosing system.
The burst tolerances of rupture disks are typically about ±5% for set pressures more than 40 psig.
Purposes of Rupture Disks
A rupture disk is a sensitive relief device designed to rupture at a pre-determined pressure and temperature. It is a means of providing protection for personnel and equipment. As such, it must be a fail-safe device. Rupture disks are used where instantaneous and full opening of a pressure relief device is required. These devices are also utilized where "zero" leak-age is required of a relief device. These devices can also be used in series as "quick opening" valves.
Rupture disks may be used either in primary relief, in secondary relief, in series with a Relief valve, or for other functions like "quick opening" valves.
If used for primary relief, the rupture disk is the only device utilized for pressure relief. As such, it has the advantages of being leak tight, an instantaneous response time, minimum pressure drop, lowest cost, very high re-liability, and minimum maintenance. It has the disadvantage that it must be replaced after each rupture occurrence, and allows venting until system pressure equals downstream pressure.
When used in a secondary relief capacity, the rupture disk provides a backup vent to a primary relief device, usually a Relief valve. Its purpose here is usually to provide additional protection against an unlikely but possible major event that would exceed the capacity .of the primary relief device