【2026 Control System】Basis and Key Points for Identifying Hidden Dangers in GDS Systems
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1. The inspection is based on GB/T 50493-2019 \"Design Code for Detection and Alarm of Flammable/toxic Gases in Petrochemical Industries\": the distance between the detectors and the source of leakage should be ≤7.5 m for flammable gases, while the height of toxic gas detectors should be between 0.3–0.5 m. It is also governed by JJG 693-2023 \"Calibration Regulations for Flammable Gas Detection and Alarm Devices\": the uncertainty of the calibration gases should be ≤2%, with at least 3 calibration points required. Additionally, NFPA 72-2022 \"Code for Fire Alarm Systems\" specifies that the response time should be ≤30 s for flammable gases and ≤60 s for toxic gases
2. Key inspection points: Reasonableness of point placement: Verified by combining gas density and leakage patterns, as well as CFD simulations and HAZOP results. Calibration compliance: Check the standard gas certificate to confirm it matches the testing gas, with a frequency of every six months or one year. Interlocking function: After an alarm is triggered, it verifies that the fan starts within ≤60 seconds and that the air exchange rate is ≥12 times per hour; simultaneously, it activates the ESD shut-off valve.
3. Case: A device had its methane probe installed at a height of 1.5 meters, which violated GB/T 50493; it was ordered to be moved to a height of 0.3 meters above the ceiling.
For reference: In the operation of hazardous chemicals and chemical processing plants, automation systems such as DCS, PLC, SIS, and GDS serve as both the \"brain\" for production control and the \"last line of defense\" for safety protection. During hazard identification, it is necessary to refer to **standards (GB), international standards (IEC/ISA/API), and industry regulations**, as well as documents such as the \"Guidelines for Identifying and Addressing Safety Risks and Hazards in Hazardous Chemical Enterprises\", to ensure that the entire process of design, operation, and maintenance remains compliant and under control.
Specific requirements: The \"Guidelines for the Identification and Rectification of Safety Risks and Hazards in Hazardous Chemical Enterprises\" specify mandatory items such as DCS/SIS independence, GDS coverage rate, and PLC emergency stop functions.
“Regulations on the Safety Management of Instrumentation Systems in Chemical Enterprises”: Any modification to the interlock logic must go through the MOC process, along with a HAZOP analysis.
\"Guidelines for the Implementation of Process Safety Risk Management in Chemical Enterprises\": The SIS system must undergo full-circuit testing annually.
MOC scope expansion: In addition to logical modifications, it also includes hardware replacement, firmware upgrades, and network structure adjustments.
1. Industrial control network security: In accordance with GB/T 30976-2014 Guidelines for Security Protection of Industrial Control Systems, identify issues such as weak passwords, remote access, and patch management.
2. Emergency plan coordination: Check whether the alarms from the GDS/SIS are linked to the emergency broadcast system and the dispatch center, to ensure timely transmission of information.