Essential precautions for the safe operation of pressure vessels

Thread Content

A pressure vessel is a sealed device used to contain gases or liquids and withstand certain pressures. The causes of accidents involving pressure vessels are often multifaceted; generally speaking, they include issues such as design flaws, manufacturing defects, improper installation, misuse, inadequate inspection and maintenance, insufficient safety accessories, and chaotic technical management. To ensure the safe operation of pressure vessels, the following aspects must be addressed: 01 Smooth operation – During the operation of pressure vessels, frequent changes and large fluctuations in pressure are detrimental to the vessel’s resistance to fatigue damage. The operating pressure should be kept stable as much as possible. At the same time, during operation, the container should also avoid sudden changes in shell temperature to prevent excessive thermal stress. When loading a pressure vessel (increasing pressure or temperature) and unloading it (decreasing pressure or temperature), the rate should not be too fast, in order to prevent rapid changes in pressure or temperature from having adverse effects on the vessel. 02 Prevent overloading: Preventing pressure vessels from being overloaded mainly involves preventing excessive pressure. In reaction vessels, the feed rate and reaction temperature must be strictly controlled to prevent the reaction from getting out of control and causing overpressure in the vessel. When filling storage vessels with feed, precise measurement is necessary to avoid overfilling, thereby preventing the material’s thermal expansion from leading to overpressure in the vessel. 03 Status Monitoring: Pressure vessel operators must continuously monitor the operating condition of the vessel during its operation, detect any abnormalities that may arise, and take appropriate actions to ensure safe operation. The supervision and control of the container’s operating status are primarily carried out in terms of process conditions, equipment status, safety devices, etc. Process conditions: mainly check whether the operating pressure, temperature, liquid level, etc. are within the ranges specified in the operating procedures ； Whether the chemical composition of the working medium inside the container meets the requirements, etc. Equipment condition: primarily check the container body and those parts directly connected to it, such as access holes, valves, flanges, and the connections for pressure, temperature, and level instruments, for any deformation, cracks, leaks, corrosion, or other defects or suspicious signs ； Check whether there is any vibration or wear on the containers, as well as the pipes connected to them and other related equipment ； Whether the equipment’s insulation (cooling) is in good condition, etc. Safety devices involve primarily checking the condition of various safety accessories and measuring instruments, such as whether any of these instruments are inaccurate or clogged ； Whether interlocks and alarms are operating reliably, whether they are within their permitted service life, and whether outdoor equipment freezes in winter, etc. 04 Emergency shutdown: When a pressure vessel exhibits any one of the following abnormal conditions, the operator must immediately take emergency measures and report to the relevant departments of the unit in accordance with the prescribed procedures. These phenomena mainly include: 01 work pressure, sudden changes in the medium, medium temperature or wall temperature exceeding allowable values, and the situation not being effectively controlled despite taking measures ； 02 Critical safety defects such as cracks, bulging, deformation, and leaks occur in the main stressed components ； Failure of safety accessories ； Takeover, damaged fasteners; it is difficult to ensure safe operation ； 03 Fires pose a direct threat to the safe operation of pressure vessels ； overfilling ； The liquid level is out of control ； Severe vibration in pressure vessels and pipelines endangers safe operation, etc.