The Application Method of the Rupture Disc
If the rupture disc is to be used as the primary or a singular pressure reliever, it can be used as a complementing
means to protect the overpressure. The pressure setting should not exceed the maximum allowable working
pressure (MAWP.) It should also be capable of preventing the pressure vessel from developing a pressure that
exceeds 10% of the maximum allowable pressure or 3psi
Secondary (Multiple) Relief (Used as the two or more safety devices)
A rupture disc device may be used as a secondary relief for other rupture discs or safety valves.
When a multiple number of reliefs are used, the burst pressure should not exceed the MAWP of a single pressure
vessel. The rest should not exceed 105% of the MAWP except for the external fi re reliefs.
Also, it should be possible to prevent the pressure from rising by 16% or 4psi beyond the MAWP of the pressure
Combination Relief (Used in combination with the safety valve)
The rupture disc device can be installed between the safety valve and the process. It is done to prevent the
leakage and water leak through the safety valve and protect the safety valve from corrosion. In case a safety
valve is mounted between the inlet for the safety valve and the vessel along with the rupture disc, the confi rmed
capacity by the safety valve is either recognized as to be 90% of the rated fl ow rate of the valve or as the actual
value confi rmed after assembling the valve and the disc. There are a number of monitoring instruments, such as a
pressure gauge, mounted between the rupture disc device and the safety valve. Such devices make it possible to
monitor the disc for any ruptures or leakages.
External Fire Relief (Used as the external re safety devices)
In case the pressure vessel is exposed to additional risks due to unexpected external heat, including a fire,
the pressure reliefs should be installed in order to protect the equipment from overpressure. In this case, the
pressure reliefs added on should be capable of preventing the pressure from rising beyond 21% of the MAWP.
The pressure setting shall not exceed 110% of the MAWP. Pressure reliefs, which are mounted on the vessel
without a permanent supply connector, used for storing liquefi ed, compressed gas in ambient temperature, and
with the primary purpose of protecting the pressure vessel from leakage due to external heat, should be capable
of preventing the pressure from rising beyond 20% of the MWAP of the vessel.