Identification of major hazard sources in production facilities — shut-off valves
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I’d like to ask the experts: According to GB18218, a “production unit” refers to installations and facilities used for the production, processing, and use of hazardous chemicals. When there are shut-off valves between such installations and facilities, these shut-off valves serve as dividing boundaries, thereby creating separate units. ” In fact, within the same production workshop, with different process routes and two distillation systems, should they be considered major hazard sources separately? But this workshop may need to be managed in accordance with the regulations for major hazard sources. So what is the purpose of this cut-off valve? 5. In the case of fine chemicals, a single building may contain separate systems and numerous units – how should these be divided? Answer: In my personal view, it should be classified based on the mutual influence during the accident situation. 6. If, in the same production workshop, three sub-production units—Production Unit 1, Production Unit 2, and Production Unit 3—are established, it is determined that the q/Q value for each of these three sub-units is greater than 1. Are there three major hazard sources? Or should we perform a combined calculation? The same principle applies to other unit types such as storage. Answer: Calculate them together. 7. Suppose that in the same production workshop, there are three sub-units: Production Unit 1, Production Unit 2, and Production Unit 3. It has been determined that for these three sub-units, the value of q/Q is less than 1 in each case. However, the total value of q/Q is greater than 1. Should this be regarded as a major hazard source? Answer: The classification of the unit may be inappropriate; it should be identified as a major hazard source. https://www.igex.org.cn/view/index/602/news.html
The question from a friend on the first floor regarding the classification of production units that represent major hazard sources is very representative. 1. Major hazard sources are classified into two categories: production units and storage units. 2. The production facility is divided into several production units to simplify the scope of design calculations; major hazard sources must be calculated together. 3. There are two distillation units; this is merely a division of the processes within the production facility. It cannot be arbitrarily defined as production units by individuals – such divisions must be made strictly in accordance with industry standards by professionals in design or evaluation. 4. The cut-off valve is merely a valve; it is a secondary factor in classifying devices as major hazard sources, and not a fundamental standard.
5. In actual production, for reasons related to safety costs, chemical companies prefer not to install two units that represent major hazards. The supervision system for personnel working in such units is very strict; operators and managers must hold relevant certificates, and there are also requirements regarding educational qualifications. Additionally, safety supervision and early warning systems are particularly costly.
This post was last edited by lotuscsx on 2026-6-1 19:59. Professionals in design or evaluation are strictly classified according to industry standards – what are these standards? Isn’t it 18218? The standards should clearly define these aspects (since they weren’t considered carefully at the time, they should be revised and supplemented with clarifications). There shouldn’t be any room for interpretation or discretion in their application. As defined in GB18218, a \"production unit\" refers to the devices and facilities used for the production, processing, and use of hazardous chemicals; when there are isolation valves between such devices and facilities, those valves serve as boundaries to divide them into separate units. ””Since they are divided into production units, they should be evaluated on a unit basis – then why merge them? Isn’t it based on individual buildings as the evaluation units? !
For example, I work at a company that handles major hazard sources in northern Anhui; this involves tank areas for such hazards, as well as storage tanks for epichlorohydrin and methanol. There are two hazardous chemical storage tanks; the storage capacity of each tank individually is greater than 1. We have simply combined them into one major hazard area. 1 technical supervisor, 3 operators. We failed to establish two major hazard tank farms. Multiple personnel and instrument systems. The production workshop is a workshop representing a major hazard; it is a four-story building that produces 10,000 tons of the new solid TBK material. On the fourth floor, in the synthesis section, 8 synthesis reactors use epichlorohydrin; on the third floor, methanol is used for solvent extraction. On the second floor are the centrifugation unit and the methanol distillation unit. On the first floor are the methanol receiving tank and the epichlorohydrin receiving tank. For our calculation of major hazard sources, at least four production units must be selected; they can only be combined for calculation as one major hazard source workshop. Without combined calculation, new workshops must be built to spread out the equipment and hazardous materials, doubling the investment.