Core examination points in the Safety Engineer exam’s “Chemical Safety” section – Safety in chemical production processes
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This post was last edited by The one on 2026-6-9 11:17 🌟 Key Topic 1: Plant Safety Planning and Design 1. Safety Planning During the preliminary assessment or feasibility study phase of a construction project, it is necessary to identify hazards, analyzing process-related risks, natural conditions, and their impact on surrounding protected areas. 2. Qualifications of design units: For large-scale construction projects involving the “two key points and one major hazard” (hazardous chemicals under key supervision, hazardous chemical processes under key supervision, and major hazards related to hazardous chemicals), the design unit must possess a Class-A comprehensive engineering design qualification or a Class-A qualification in the relevant industry or specialty. 3. Hazard and Operability Study (HAZOP): HAZOP should be conducted during the basic design phase of construction projects ； The process package design documents for construction projects classified as “two key items and one major item” shall include a process hazard analysis report, and the design unit shall provide a list of the main risks associated with the facility. 4. Control room/office layout: Control rooms and shift change rooms that handle explosive hazardous chemicals should not be located within the plant area. Control rooms and shift-change rooms associated with Class A and Class B fire hazards should not be located within the plant area; if their placement is unavoidable, they must be designed for blast resistance in accordance with relevant standards. In factories and warehouses with Class A or B fire hazards, as well as those prone to dust explosions or poisoning risks, offices, rest rooms, outdoor operation rooms, and inspection rooms shall not be installed. 5. Circumstances requiring re-conducting a safety assessment: After the approval of the safety design documents, if there are significant changes in the surrounding conditions, a change in the construction location, major changes in key technologies/processes/products/scale, or commencement of work after the expiration of the review period, a new safety assessment must be conducted and an application for review submitted.
🌟 Key Exam Point 2: Safety Management for the First Startup of a Plant 1. Verification of safety conditions prior to feeding materials – This must be completed before starting up a newly built plant for trial operation; feeding materials is not allowed without such verification. 2. Production preparation includes technical preparation, organizational preparation, material preparation, and external condition preparation. 3. Single-unit testing and integrated testing
Single-unit testing: This is primarily conducted to verify the performance of mechanical equipment. Safety precautions must be implemented; in explosion-hazard areas, explosion-proof electrical equipment must be used. A detailed test plan must be prepared and approved. Integrated commissioning: Using water, air, etc. as media to simulate process operation, and testing the performance of all equipment in the system except for the driving equipment, as well as its interlocks. 4. Commissioning with material feeding must be carried out in accordance with the approved plan. Forced testing is strictly prohibited, as is making corrections while testing. The test run must be closely monitored; any abnormalities must be addressed by immediate cessation.
Single-unit testing: This is primarily conducted to verify the performance of mechanical equipment. Safety precautions must be implemented; in explosion-hazard areas, explosion-proof electrical equipment must be used. A detailed test plan must be prepared and approved. Integrated commissioning: Using water, air, etc. as media to simulate process operation, and testing the performance of all equipment in the system except for the driving equipment, as well as its interlocks. 4. Commissioning with material feeding must be carried out in accordance with the approved plan. Forced testing is strictly prohibited, as is making corrections while testing. The test run must be closely monitored; any abnormalities must be addressed by immediate cessation.
🌟 Key Exam Point 3: Safe Operation 1. Management of operating procedures: ◦ Operating procedures and process control parameters must be established; failure to do so constitutes a major safety hazard. ◦ The operating procedures should include steps such as startup, shutdown, operation, and abnormal condition handling, as well as safety requirements. 2. Driving safety requirements: ◦ Strictly implement blind plate management. ◦ Confirm that public utilities such as water, electricity, and steam are in good condition. ◦ Strictly follow the plans and operation tickets; temperature/pressure increase must be carried out in accordance with the prescribed curves. 3. Safety requirements for shutdown: ◦ Strictly follow the plan; the reduction of flow rate, temperature, and pressure must be carried out gradually. ◦ Equipment pipelines must be emptied, cleaned, and purged until they meet the requirements. ◦ When parking in winter, protection against freezing and condensation is necessary. 4. Operational safety requirements: ◦ Operation at temperatures, pressures, or liquid levels exceeding the limits is strictly prohibited. ◦ It is strictly prohibited to have untimely dehydration and condensate drainage, as well as material cross-contamination. ◦ Strictly adhere to the inspection regulations, and address any leaks immediately.
🌟 Core Exam Point 4: Safety Management of Major Hazardous Sources 1. Identification and classification: In accordance with the “Identification of Major Hazardous Sources of Hazardous Chemicals” (GB 18218), calculate the sum R of the ratios of the actual quantities of hazardous chemicals present to their threshold quantities. Classification is then done based on the value of R (Level 1: R≥100； Level 2: 50≤R＜100 ； Level 3: 10≤R＜50 ； Level 4: 1≤R＜10). 2. Safety assessment: A safety assessment of major hazard sources is conducted annually, and the assessment should be updated promptly in case of certain circumstances (such as changes in the types/quantities of hazardous chemicals, changes in processes/technologies, or the occurrence of accidents). 3. Monitoring and emergency response: There must be a continuous data collection and monitoring system for information such as temperature, pressure, liquid level, and flow rate, as well as a detection and alarm system for flammable/toxic gases ； Hazardous chemical storage areas involving Class 1 and Class 2 major hazard sources must be equipped with emergency shutdown functions, while Class 1 and Class 2 storage areas for toxic/liquefied/cutely toxic liquids must have independent Safety Instrumented Systems (SIS). 4. Determination of major hazards: Hazardous chemical tank farms classified as first- or second-level major hazard sources fail to implement emergency shut-off functions ； Chemical storage areas that are classified as major hazard sources of level 1 or 2 and involve toxic gases, liquefied gases, or highly toxic liquids, and which do not have an independent safety instrumented system, are all considered to pose serious accident risks.
🌟 Core Exam Point 5: Change Management
1. Classification of changes:
• Process and technical changes (such as changes in raw materials, catalysts, process routes, process parameters, operating procedures, etc.). ◦ Changes to equipment and facilities (such as changes in equipment model/material/control system/safety facilities, etc.). ◦ Management of changes (e.g., replacement of the responsible person/process owner, change of suppliers, updates to operating procedures, etc.). 2. Change procedure: ◦ Application: Fill out the change application form as required; it is managed by a designated person. ◦ Approval: Depending on the level of change, it shall be approved by the respective responsible person. Major changes must be reviewed by the competent department and approved by the company’s senior management. ◦ Implementation: Carried out by the competent authority. ◦ Acceptance: After completion, the competent authority organizes an acceptance inspection. 3. Risk management: A risk analysis must be conducted prior to implementing changes, and control measures should be established ； After the changes, documents such as operating procedures, process control parameters, and drawings should be updated promptly, and relevant personnel should be trained.
1. Classification of changes:
• Process and technical changes (such as changes in raw materials, catalysts, process routes, process parameters, operating procedures, etc.). ◦ Changes to equipment and facilities (such as changes in equipment model/material/control system/safety facilities, etc.). ◦ Management of changes (e.g., replacement of the responsible person/process owner, change of suppliers, updates to operating procedures, etc.). 2. Change procedure: ◦ Application: Fill out the change application form as required; it is managed by a designated person. ◦ Approval: Depending on the level of change, it shall be approved by the respective responsible person. Major changes must be reviewed by the competent department and approved by the company’s senior management. ◦ Implementation: Carried out by the competent authority. ◦ Acceptance: After completion, the competent authority organizes an acceptance inspection. 3. Risk management: A risk analysis must be conducted prior to implementing changes, and control measures should be established ； After the changes, documents such as operating procedures, process control parameters, and drawings should be updated promptly, and relevant personnel should be trained.
📝 Practice Question 1. 【Single-choice】Which of the following statements regarding the safety design of chemical engineering construction projects is correct? （） A. For large-scale construction projects that fall under the category of “two key aspects and one major issue”, the design unit required can have a comprehensive Class B qualification for engineering design. B. A Hazard and Operability Study (HAZOP) should be conducted during the preliminary design phase of a construction project. C. When control rooms and shift change rooms for facilities that handle explosive hazardous chemicals need to be located within the facility area, blast-resistant design measures must be implemented. D. In factories with Class A fire hazards, rest rooms for employees can be installed there
【Answer】B Explanation: Option A is incorrect; for large-scale construction projects that fall under the category of “two key points and one major aspect”, the design unit must have a comprehensive Class A qualification or a Class A qualification specific to the relevant industry/field； Option C is incorrect. Control rooms and shift-change rooms related to explosive hazardous chemicals should not be located within the processing area (rather than “they must be blast-resistant if it is necessary to locate them there”) ； Option D is incorrect. In factories and warehouses with Class A or B fire hazards, as well as those prone to dust explosions or toxicity risks, offices, rest rooms, external control rooms, and inspection rooms shall not be installed. Therefore, the answer is B.
2. 【Single-choice】A newly built large-scale chemical plant is about to begin its commissioning trial operation. Regarding the safety management for the first start-up and testing of this plant, which statement is incorrect? A. Before starting up a newly installed unit for trial operation, it is necessary to confirm the safety conditions prior to feeding materials; feeding materials is not allowed without such confirmation. B. Single-unit testing is primarily used to assess the performance of mechanical equipment, and explosion-proof electrical appliances must be used in areas where explosions could occur. C. During joint trials, safe media such as water or air are used in place of production materials to simulate the actual processing process. D. If any abnormalities are detected during the trial operation but the risks can be controlled, corrections can be made while continuing with the operation in order to maintain progress
【Answer】D Explanation: Commissioning with feed must be carried out in accordance with the approved plan; forced commissioning is strictly prohibited, as is making corrections while the commissioning is in progress. Upon detecting any abnormalities, operations must be stopped immediately. Option D is incorrect; thus, it meets the requirements of the question.
3. 【Single-choice】Which of the following statements regarding the safe operation of chemical processing units is incorrect? （） A. If an enterprise fails to establish operating procedures and process control indicators, it can be deemed to have major accident hazards.
B. During unit startup, heating and pressurization operations must be carried out strictly in accordance with the specified curves to prevent localized overheating.
C. During unit shutdown, reduction of flow rate, temperature, and pressure should be performed gradually; equipment and pipelines must be emptied, cleaned, and purged to meet requirements.
D. Under normal operating conditions, when the liquid level is relatively high, it is permissible to temporarily exceed the design upper limit to maintain process balance
B. During unit startup, heating and pressurization operations must be carried out strictly in accordance with the specified curves to prevent localized overheating.
C. During unit shutdown, reduction of flow rate, temperature, and pressure should be performed gradually; equipment and pipelines must be emptied, cleaned, and purged to meet requirements.
D. Under normal operating conditions, when the liquid level is relatively high, it is permissible to temporarily exceed the design upper limit to maintain process balance
【Answer】D. Explanation: The operating safety requirements clearly stipulate that operation under conditions of excessive temperature, pressure, or liquid level is strictly prohibited. The statement in option D is incorrect, thus it meets the requirements of the question.