Discussion on several issues in GB 18218-2018: Identification of Major Hazard Sources of Hazardous Chemicals

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Discussion on Several Issues in GB18218-2018 \"Identification of Major Hazard Sources for Hazardous Chemicals\": I. The issue of dividing storage units – When identifying major hazard sources in hazardous chemical storage areas, should the entire storage area be considered as one identification unit, or should each group of tanks separated by fire dikes be treated as an individual identification unit? The former calculates the total storage capacity of the tank area; there is at most one major hazard source, and the level of that major hazard source may be relatively high ； The latter calculates the reserve of a single tank group; multiple tank groups may constitute a major hazard source, but their risk level is not as high as that of the former! I personally lean towards the latter, as the standards clearly state that \"the tank farm is divided into separate units using the fire dike as a boundary,\" which means that the tank farm should also be divided into distinct identification units based on the fire dike, rather than treating the entire tank farm as a single identification unit ； If the entire tank farm is considered as the identification unit, it would not be expressed in this way: “bounded by the fire dike of the tank farm,” and this phrase also seems redundant! Moreover, by following the classification logic in the standards of \"production unit – isolation valve\" and \"warehouse – separate building\", the classification of major hazard sources becomes clear and well-defined, with defined boundaries; this is different from previous approaches and facilitates management! The results of identification and classification have a significant impact; for example, tank areas that represent major hazard sources of level 1 or 2 and involve toxic gases, liquefied gases, or highly toxic liquids should be equipped with independent safety instrument systems, etc. There are different requirements regarding whether it constitutes a major hazard source and what level of major hazard source it represents; the installation of safety facilities, safety management practices, and regulatory oversight all vary accordingly! II. Article 4.1.2 of the standards regarding the determination of the critical quantity for flammable liquids stipulates that, for those within Table 1, the values shall be determined in accordance with Table 1 ； Those not listed in Table 1 shall be determined according to Table 2 ； Some experts believe that for the flammable liquids listed in Table 1 (such as methanol, with a critical amount of 500 tons), if classified according to items 5.1 or 5.2 in Table 2 for flammable liquids, their critical amounts are 10 tons and 50 tons respectively (which is 10 times and 50 times higher than those in Table 1); this results in a significant difference in the identification outcomes, with considerable implications! In my opinion, the standards are clearly stated: Tables 1 and Table 2 represent a sequential relationship, an exclusionary relationship (what is listed in Table 1 cannot be used in Table 2), rather than a parallel relationship; one can use either Table 1 or Table 2, depending on which set of standards is more stringent III. The selection of the α value: The standards require that the α value be determined according to the population living within a radius of 500 meters outward from the boundary of the site where the major hazard source is located, as indicated in Table 5. Many experts disagree: 1. If the permanent population refers only to residents who live there permanently, and there are no households around many enterprises, is it reasonable to assign a count of 0 for such places? 2. Is the factory boundary expanded outward by 500m here, including or excluding the shift dormitories located outside the production area of this enterprise? 3. Does the permanent population include 24/7 on-duty personnel such as operators, office staff, and security guards from nearby enterprises who work around the clock? IV. Determination of the β value for sulfur monochloride 1. Basic properties and hazard classification of sulfur monochloride: Refer to the 2002 edition of the “List of Hazardous Chemicals” (although it is no longer current, it can be used for reference); sulfur monochloride falls under the category of acidic corrosive substances 81032, with UN number 1828 ； Refer to Table 1 of GB18218-2009: Sulfur chloride is a toxic substance, with a critical amount of 1 ton (note that it is not listed as a toxic gas) ； According to Table 1828 of GB 12268-2012, the list of hazardous goods, sulfur chloride is classified under Category 8, Corrosive substances, with packaging category I. According to the Catalogue of Hazardous Chemicals (2015 edition), the hazard category for sulfur monochloride is: Acute toxicity – oral, Category 3* ； Skin corrosion/irritation, Category 1A ； Severe eye damage/eye irritation, Category 1 ； Specific target organ toxicity – single exposure, Category 3 (respiratory irritation) ； Harm to aquatic environment – Acute hazard, Category 1 ； 2. Refer to Table 1 of GB18218-2018: for sulfur monochloride (sulfur chloride, CAS: 10025-67-9), the critical amount is 1 ton ； Tables 3 and 4 do not specify any corresponding β values (the boiling point of sulfur monochloride is 138°C) ； Is it possible that the GB18218-2018 standard is missing? Could someone with expertise please shed some light on this? At present, in accordance with Annex 1 to Order No. 40 issued by the former Work Safety Administration, β is classified as an \"other type of hazardous chemical\" with β=1 ； We welcome everyone to share their opinions and engage in discussions. We also hope that the relevant authorities will provide timely answers to questions, so as to prevent incorrect identification and classification of major hazard sources, which could affect enterprises!