The \"Code for Process Design of Safety Pressure Relief Systems in Petrochemical Plants\" will come into effect on November 1

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The \"Code for Process Design of Safety Pressure Relief Systems in Petrochemical Plants\" will come into effect on November 1st. SH/T 3241-2025 will be implemented on November 1, 2025; it consists of 7 chapters and 2 appendices, and provides comprehensive regulations specifically for the process design of safety pressure relief systems in petrochemical plants. The key aspects of this code can be summarized as follows: Basic framework and principles – It specifies that this standard applies to the process design of safety pressure relief systems in petrochemical plants, and defines key terms such as main pipelines and atmospheric venting. The design must take into account various abnormal conditions of the device and rule out force majeure factors. It is also necessary to determine pressure levels or establish separate systems based on the back pressure at the discharge points and the properties of the medium. Under normal operation, pressure reduction devices should be used first to lower pressure, rather than safety relief devices. The detailed design specifications for various media establish differentiated requirements based on the characteristics of each medium. For example, liquids cannot be directly discharged into the plant’s overall gas safety pressure relief system ； The release of hydrogen gas must be controlled in terms of speed, and the outlet of the vent pipe needs to be protected from ignition ； Gases containing powder are discharged to the appropriate treatment facilities; when discharged directly into the atmosphere, the outlet must be located away from areas where people and equipment are present ； Media that are prone to aggregation need to be treated to prevent aggregation and clogging; for ultra-high-pressure media, specialized devices such as hydraulic emergency relief valves should be used preferentially. In addition, calculation methods for discharge and preprocessing requirements for high-viscosity media such as gas-liquid two-phase flow and slurry are also specified. Special specifications for atmospheric release: Only non-flammable and non-toxic media may be released directly into the atmosphere, and risks such as asphyxiation and fire must be assessed. If special media must be released into the atmosphere, it is necessary to comply with regulatory and environmental assessment requirements; various safety factors such as the accumulation of flammable mixtures and the risk of human poisoning must be thoroughly analyzed. Additionally, the Mach number at the outlet of the release pipeline must be kept below 0.75, and flame arresters are generally not installed at the outlet. Load determination and emission reduction measures: The maximum design load for system main pipes, trunk pipes, etc. should be determined by taking into account various accident scenarios and the combined effects of failures; the flow rate that results in the greatest pressure loss is then selected as the hydraulic design load. Emission reduction measures are also provided, including optimizing processes, conducting operational condition simulation analyses, and improving the reliability of safety instrument systems; when using safety instrument systems for emission reduction, it is necessary to control the probability of circuit failure.