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A rupture disc is a mechanism that will fail if the pressure in a sealed container surpasses an upper limit, thus allowing the pressure to drop before other unwanted events may occur. These safety valves are used in many applications and serve a wide variety of needs. They are also known as bursting discs or burst diaphragms.
Typically, once the rupture disc fails, it cannot be reset and must be replaced instead. This design requirement is based on the reasoning that to maintain safe operations, the cause of the overpressure condition should be found. The equipment involved and the surrounding equipment and structures should also be inspected before reuse.
Pressure relief safety devices are manufactured as a system. The correct holders must be employed, as well as the correct parts themselves. While the wrong components may physically fit, the tolerances, design strain, or other parameters may sufficiently differ and yield unnecessarily low pressure failures or allow overpressure conditions to continue.
Important design criteria for a rupture disc include, foremost, that the disc fail at the specified pressure within the range specified by the manufacturer. Differences in pressure limits are achieved by variations in the material properties, shape, and size of the disc and the mounting system. Additional design criteria may include non-fragmentation of the disc, use for sterile conditions, or biological containment systems that allow pressure to escape but not any biological materials. A rupture disc destined for service in a nuclear environment, such as a nuclear submarine or power plant, is subjected to very strict design requirements. The material properties, particularly the friability, or ease of breakage, may change should the disc be subjected to radiation.
The original rupture disc was developed in 1931 by BS&B Safety Systems. The type B disc was sold beginning in 1934. The type B rupture disc has been used in hundreds of thousands of applications since that time. The pressurized side is a concave, bowl-like disc. As pressure builds, the disc experiences tension forces as the material stretches or bulges outward.
Specialized uses of rupture discs include those designed for tanks in transit, such as by train or truck. The movement of liquid inside the vessel requires the rupture disc to be non-reactive with any of the components within the liquid. Hazardous materials may require a second rupture disc that fails at a higher pressure to contain the material despite the overpressure condition.
Good article! You may also know that there have been some recent advancements in high performance rupture discs. The company I am the most familiar with is Fike Corporation who have been around since 1945, but I am sure there are other companies as well.