A rupture disk is a safety device that prevents damage and injury caused by pressure problems in machines. It is a metal or synthetic ring that bursts when pressure becomes too high. It is commonly used in aerospace, pharmaceutical and food manufacturing, and medical appliances. The disk is usually small and located in the internal parts of valves and other distribution points. The design criteria include material properties, shape, and size of the disk and mounting system. Once a disk fails, it must be replaced, and affected equipment and facilities should be inspected before reuse. Specialized uses include those designed for tanks in transit and hazardous materials.
A rupture disk, also known as a “rupture disk” or “disc diaphragm,” is a mechanical component typically installed as a safety device to prevent damage and injury caused by pressure problems within a machine or other device. It is essentially a metal or synthetic ring that is inserted into the internal chambers of something like a pressurized valve or pipe. If and when the pressure becomes higher than the device can handle, the disc bursts or ruptures, effectively halting mechanical activity. In almost all cases, the disk can only be used once; once it breaks, it cannot be resealed. Replacing it can take some time, but usually saves a lot of money and effort compared to the damage that often occurs when internal pressure gets out of control. A number of different devices use this type of mechanism, although it tends to be most common in aerospace and aviation, pharmaceutical manufacturing and processed food manufacturing, and medical appliances.
Most common applications
These types of devices are very common in a range of industrial machines, usually in situations where there is a need to regulate the forced pressure within a given chamber or valve. In aerospace, for example, this occurs in fuel chambers and cabin pressure systems for aircraft and ships directed high into the atmosphere or beyond. They are also heavily used in boilers and steam pressure vessels, both common in food and drug manufacturing. Some medical devices, especially those that rely on hydraulics, can also use them.
While most machines and appliances in these categories are quite large, disks tend to be smaller. They are usually made specifically for the appliance they are installed in, but are typically located in the internal parts of valves and other distribution points.
Shape and characteristics
The pressurized side of most discs is concave and bowl-like. As the pressure builds, the disc experiences tensile forces as the material stretches or bulges outward. The original rupture disc was developed in 1931 by BS&B Safety Systems, and was improved and slightly modified into what is known as the “B-type disc” starting in 1934. The B-type disc was used in hundreds of thousands of applications since then, and is the prototype for most modern models.
Basic design criteria and manufacturing
The most important design criterion is usually that the disc fails at the specified pressure within the manufacturer’s specified range. Differences in pressure limits are achieved by variations in material properties, shape and size of the disc and mounting system. Additional design criteria may include non-fragmentation of the disk, use for sterile conditions, or biological containment systems that allow pressure to escape but not biological or other materials.
Disks intended for service in a nuclear environment, such as a nuclear submarine or power plant, are typically subject to very stringent design requirements. Material properties, particularly friability, or ease of breaking, may change if the disc is subjected to radiation. Consequently, devices in these categories should be regularly tested and inspected to ensure their integrity.
In most cases, these types of pressure reducing safety devices are manufactured as a system. The correct mounts must be employed, as well as the correct parts themselves. While the wrong components may physically fit, tolerances, design strain, or other parameters may differ sufficiently to cause unnecessarily low-pressure failures or allow overpressure conditions to persist.
Consequences of bankruptcy
Typically, once a disk fails, it cannot be recovered and must be replaced. This design requirement is based on the reasoning that to maintain safe operations, the cause of the overpressure condition must be found. Affected equipment and surrounding equipment and facilities should also be inspected before re-use.
Specialized uses
Specialized uses include those designed for tanks in transit, such as in trains or trucks. The movement of the liquid within the vessel requires that the rupture disk be non-reactive with any of the components within the liquid. Hazardous materials may require a second rupture disk that fails to contain the material at a higher pressure despite the overpressure condition.
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