blowout disc

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Introduction to blast discs: Blast discs can rupture at specified temperatures and pressures to release pressure. The rupture disc device consists of a rupture disc and a holder. A burst disc is a component that ruptures to release pressure at a specified burst pressure and temperature, while a holder is an auxiliary component installed at an appropriate location on the container to hold the burst disc in place. The rupture disc safety device has advantages such as simple structure, sensitivity, accuracy, no leakage, and strong discharge capacity. It can operate reliably in viscous, high-temperature, low-temperature, and corrosive environments, making it an ideal safety device for ultra-high pressure vessels. Blowout valves are important safety devices that prevent pressure equipment from suffering damage due to overpressure, and they are widely used in various industrial sectors such as chemicals, petroleum, light industry, metallurgy, nuclear power, dust removal, firefighting, and aviation. Working principle of the rupture disc: A rupture disc device is a pressure-relief device that cannot be closed again; it is activated by the static pressure at the inlet, and pressure is released through the rupture of a pressure-sensitive diaphragm. In simple terms, it is a one-time use pressure relief device; when the pressure difference across the rupture disc reaches a predetermined value at the set burst temperature, the disc will activate (break or detach) and release the fluid. Features of rupture discs: (1) Suitable for slurry-like, viscous, and corrosive process media, in which case safety valves are ineffective ； (2) It has low inertia, allowing it to respond quickly to rapidly rising pressures ； (3) In the event of a fire or other accident, after the main pressure relief device has opened, the rupture disc can be used as an additional pressure relief device ； (4) Airtight and leak-free, suitable for pressure vessels used to hold expensive or toxic substances ； (5) There are a wide range of specifications and models; it can be manufactured from various materials, offering strong adaptability ； (6) Easy to maintain and replace. Applications of rupture discs: (1) Areas where the working medium in pressure vessels or pipelines is viscous or prone to crystallization or polymerization, and may cause the valve disc and seat of the safety valve to stick together or block the safety valve ； (2) Locations where chemical reactions of materials inside pressure vessels may cause a sudden and drastic rise in pressure, and where safety valves cannot open in time to relieve the pressure ； (3) In cases where the working medium inside pressure vessels or pipelines is a highly toxic or expensive gas, using safety valves may result in leaks, leading to environmental pollution and waste ； (4) Areas where pressure vessels and pressure pipelines must be completely drained, or where drainage can occur without any obstacles ； (5) Other applications where safety valves are not suitable but rupture discs are appropriate. Classification of rupture discs 1. Classification by type (1) Convex rupture discs: The system pressure acts on the concave surface of the rupture disc ； (2) Inverted-dome rupture disc: System pressure acts on the convex surface of the rupture disc ； (3) Flat type: The system pressure acts on the flat surface of the rupture disc. 2. Classified by material: (1) Metals: stainless steel, pure nickel, Hastelloy, Monel, Inconel, titanium, tantalum, zirconium, etc ； (2) Non-metals: graphite, fluoroplastics, plexiglass ； (3) Metal combined with non-metal. Technical terms related to rupture discs: Back pressure refers to the static pressure present at the outlet of a rupture disc device when the rupture disc undergoes rupture or discharge. If the pressure is lower than atmospheric pressure, it can be called vacuum pressure. Backpressure support: refers to the component in a rupture disc device used to prevent the rupture disc from failing due to reverse pressure differences. If the system pressure is below atmospheric pressure, it is usually referred to as vacuum support. Batch: Several rupture discs of the same specifications that are manufactured using the same batch of material together are referred to as one batch. Bursting discs (safety discs): Pressure relief devices that cannot be resealed after bursting at a set pressure. When the pressure or vacuum level exceeds the permissible limits, they release the excess pressure, thereby ensuring the safety of individual components or the entire system. Blade assembly (explosion-proof blade assembly): All components installed on the clamp in order to fulfill the functional requirements of the design. Blowout disc device (explosion-proof disc device): A non-recloseable pressure relief device that is controlled by pressure difference and functions to rupture and release pressure. It includes not only individual rupture discs but also appropriate rupture disc clamps and other components. Blade holder (explosion disc holder): A component in the explosion disc assembly used to secure the explosion disc and ensure its proper performance. Burst pressure: When the system pressure difference rises to a certain level, the rupture disc opens instantaneously. The system pressure difference at the moment of opening is the burst pressure. Coating: A layer of metallic or non-metallic material (other than a lining) that covers the components of a rupture disc device. Detonation temperature: The temperature of the system at which the detonation pressure is reached. Standard type rupture disc (positive dome shape): The rupture disc opens when the system pressure rises above the tensile strength (or tension) that the material of the disc can withstand. The standard type of rupture disc is flat or arch-shaped, with the arch direction being consistent with that of the rupture pressure; that is, the rupture pressure acts on the concave surface of the positively arching rupture disc. Discharge capacity: The ability to discharge fluid after the rupture disc opens. Blowoff plate: A blowoff plate is a pressure relief device that prevents an explosion from occurring by releasing pressure when the internal pressure of a system becomes too high and could lead to an explosion. When the system pressure reaches the \"opening pressure\" value p, the burst disc will open instantly to release the pressure. Metal foil: A metal strip or sheet used for manufacturing metal rupture discs. Free flow (discharge) area: The equivalent minimum cross-sectional area for flow, after accounting for the effects of backpressure support and residual blasting components on the flow area. IP protection rating: It refers to the level of sealing protection that prevents external substances such as dust and moisture from entering electrical equipment or systems. Lining: An additional thin sheet or film attached to the metal blast disc or holder (not a coating). Manufacturing range: The manufacturing range is a pressure range determined through negotiation between the manufacturer and the user based on requirements. The average burst pressure of blast discs in the same batch must be within this pressure range. Maximum operating pressure: refers to the maximum pressure of the system that allows the rupture disc to function properly without causing excessive fatigue of the disc. Depending on the type of rupture disc, the maximum operating pressure is generally 50% to 100% of the rated rupture pressure. It is also commonly referred to as the operation ratio. Operating pressure (working pressure): The system pressure when the burst disc is functioning properly. Operating temperature (working temperature): The system temperature when the burst disc is functioning properly. Blasting tolerance: At the same blasting temperature, the actual blasting pressure can vary between a maximum value and a minimum value. The blasting tolerance refers to the allowable deviation between the actual blasting pressure and the calibrated blasting pressure. It is usually expressed as a percentage (or psig). After determining the type, model, and burst pressure of the rupture disc, the actual burst pressure must be within the allowable tolerance range. Release pressure: The maximum system pressure under release conditions. (Different from the burst pressure). Discharge temperature: The highest system temperature under discharge conditions. (Different from the detonation temperature). Inverse-dome rupture discs: Rupture discs in which the direction of doming is opposite to the direction of pressure application; that is, the pressure acts on the convex surface of the rupture disc. Composite rupture disc: A rupture disc with a structure of two or more layers, in which one of these layers features holes or gaps that help reduce the pressure exerted on the rupture disc, thereby serving to control the burst pressure. Composite rupture discs can be flat or domed. Design burst pressure: When specifying the performance requirements for a rupture disc, this is the pressure required by the customer or provided by the manufacturer at the same burst temperature. It can be expressed as a minimum or maximum value. Latest **standard: GB 567-2012 “Safety devices for rupture discs”