Classification, installation principles, and selection requirements for safety devices in pressure vessels

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Classification, installation principles, and selection requirements for safety devices in pressure vessels: Due to the operating characteristics of pressure vessels, as well as the chemical and technical properties of the substances contained within them, it is necessary to install various safety devices along with testing and control instruments in order to monitor these vessels and ensure their safe operation as well as the proper progress of the production process. Safety accessories for pressure vessels, such as safety valves, rupture disks, pressure gauges, level gauges, and temperature measuring instruments, shall comply with the provisions of the \"Regulations on Safety Supervision of Pressure Vessels\" and relevant standards. Every container operator must be familiar with and use these safety devices correctly. I. Classification of safety devices Safety devices for pressure vessels can be roughly divided into three categories based on their functions: (1) Indicating devices: Used to display the actual conditions of the medium, such as various types of thermometers, level gauges, pressure gauges, etc. (2) Control or display control devices: Devices that can adjust automatically according to the set process parameters to maintain those parameters within a certain range, such as pressure reducers, control valves, electric contact pressure gauges, automatic level gauges, etc. (3) Safety pressure relief devices: When the pressure of the medium inside a container or system exceeds a set level, these devices automatically release some or all of the gas to prevent damage caused by excessive pressure, such as safety valves and burst discs. II. Principles for installing safety devices on pressure vessels (1) Safety valves should be installed on all pressure vessels in use; however, if the pressure comes from outside the pressure vessel and is under reliable control, it may not need to be installed directly on the vessel. For example, the pressure may originate from the air storage tank of the compressor or the steam drum of the steam boiler, etc. (2) If the safety valve cannot operate reliably after installation, a burst disc should be installed, or a combined structure using both a burst disc and a safety valve should be employed. When a combined and shared structure is used, the relevant requirements of Appendix B of GB150 shall be complied with. Any burst disc connected in a composite structure must not generate fragments when it activates. (3) When the maximum operating pressure of the pressure vessel is lower than the pressure of the pressure source, a pressure reducing valve must be installed on the pipeline leading to the inlet of the pressure vessel ； If the medium conditions affect the reliable operation of the pressure reducing valve, a control valve can be used in its place. A safety valve and a pressure gauge must be installed on the low-pressure side of the pressure relief valve or control valve. (4) The level gauge for pressure vessels should be selected appropriately based on the medium contained in the vessel, its maximum operating pressure, and temperature. The installation of safety devices for ultra-high pressure vessels shall comply with the requirements of the \"Regulations on Safety Supervision of Ultra-High Pressure Vessels\".    III. Selection Requirements: The design and manufacture of safety accessories for pressure vessels must comply with the \"Regulations on Safety Supervision of Pressure Vessels\" as well as relevant national standards and industry standards; furthermore, products manufactured by units holding manufacturing licenses must be selected. If the maximum allowable working pressure is used as the basis for adjusting safety valves and rupture disks when designing a pressure vessel, this shall be indicated on the design drawings and on the vessel’s nameplate.