| Hazardous chemical accidents(hereafter,HCAs)occur frequently in China at this stage,which brings losses to lives and properties,and causes environmental damages.The failures in organizational management are considered as the system-related flaws,whose correction could substantially prevent the similar accidents from happening.Therefore,learning from the previous Chinese HCAs and investigating the statistical characteristics of their organizational management failures are necessary for making accident prevention measures.However,it is found that accident causation models were rarely applied in previous studies related to Chinese HCA analysis,so that the categories of identified organizational management failures were ambiguous and broad,which makes the statistical results could not be referred when accident prevention measures are made.In view of the research situation,in this study,Accident Causation “2-4”Model(hereafter,24Model)whose causation modules are well-defined and connected with a clear logical relationship was used as the theoretical basis and the analysis tool to investigate the safety management system failures,a type of organizational management failures,of 64 Chinese HCAs and obtain their statistical characteristics.The statistical analysis on accident causes provides the basis for accident prevention;therefore,this study belongs to the fundamental research in safety science.The research content of the thesis contains four main parts.Firstly,the causal category related to safety management system was established.Based on the standards related to the three existing safety management systems used for HCA prevention(i.e.,work safety standardization system,process safety management,and occupational health and safety management system),the preliminary safety management system framework for HCA prevention was established through the comparative study and based on the principle for screening elements.Delphi method was used and two rounds of surveys were conducted.23 experts,who had more than 10 years of experience in the chemical industry and were familiar with the processes of production,operation,storage,transportation,usage,and disposal of hazardous chemicals,took part in the surveys to establish the final framework of the safety management system.The final framework was the causal category which was the basis for the subsequent investigation and statistical analysis of safety management system failures in HCAs.Secondly,the steps for 24 Model to analyze HCAs were introduced.Event Sequence Diagram and 5-Whys Tool were introduced to establish the accident analysis steps for 24 Model usage.The feasibility of the analysis steps was demonstrated by a case study;and the advantages of 24 Model in analyzing organizational management failures of HCAs were discussed based on a comparison between the results obtained from the analysis and the official investigation report.The established steps provided the method for accident analysis.Thirdly,the macro characteristics of accident samples were investigated.The basic information(e.g.,location distribution,levels of accidents)of accident samples which contained 64 HCAs was analyzed,and two kinds of HCAs(i.e.,leakage accidents and accidents related to nonroutine activities),which had a great proportion in accident samples,were analyzed to investigate the statistical characteristics of their critical safety management system failures.Finally,the safety management system failures of the overall HCAs in accident samples were investigated.The HCAs were classified as two types(i.e.,fixed location HCAs and transport-related HCAs)and their safety management failures obtained by analyses were counted to illustrate their statistical characteristics.Moreover,the system elements which were recurrent with a high frequency were independently analyzed.By comparing the statistical results of the two types of HCAs,the common features of safety management system failures in HCAs were summarized.Main research results and conclusions of the thesis are summarized as follows.(1)The established causal category contains 29 system elements.After the comparative study and based on the certain principle for screening elements,a safety management system framework with 30 elements was initially established.The Delphi method was used and the system framework with 29 elements was finally established based on the statistical results of the two rounds of surveys.(2)The accident analysis process contains three steps(i.e.,determining the object for analysis,decomposing the accident,and analyzing the event),and the accident analysis steps are feasible.For the application of 24 Model,firstly,the organization for the accident analysis should be determined.Then,the accident should be decomposed into sequential events based on Event Sequence Diagram.Finally,in-depth analysis of each event should be conducted based on the accident analysis pathway.When tracing the latter cause from the former one,5-Whys Tool needs to be used.A larger poisoning accident was analyzed based on the established steps.Compared with the official accident report,the more detailed organizational management failures were obtained.(3)For leakage accidents caused by unsafe conditions of the equipment and facilities,flaws in “mechanical integrity” are the most common critical failures related to the safety management system contributing to unsafe conditions.Among the 64 HCAs,the number of the cases where the leakage was the initial accident reached 63%(40 cases),and 25 cases of them were due to the unsafe conditions of the equipment and facilities.However,among the 25 cases,flaws in “mechanical integrity” were recurrent as safety management system failures in 21 cases,which were characterized by lacking of:(1)inspection and maintenance procedures for facilities and the equipment;(2)procedures to ensure the new equipment and facilities were complied with technical standards;(3)quality inspection procedures for the new equipment and facilities;(4)quality inspection procedures for spare parts.In addition,the failures in “hazard identification and assessment of risks and opportunities”,“laws and regulations and other requirements”,“monitoring,measurement,analysis and performance evaluation”,and “pre-startup safety review” could also lead to unsafe conditions of facilities and the equipment.(4)“The lack of operating procedures” is the most common critical safety management system failure for accidents related to nonroutine activities.In accident samples,there were 27 accidents related to nonroutine activities(accounted for 42% of the total),and 48% of them were led by the immediate cause that “the workers within the organization worked blindly”.Therefore,“the lack of procedures for nonroutine activities” was considered as the most common critical failure related to the safety management system of such accidents.Well-established nonroutine activity procedures required effective planning of three system elements including “mechanical integrity”,“work permit” and “operating procedures”.In addition,37% of the nonroutine activity accidents were caused by illegal operations from workers within the organization,indicating the failures in “monitoring,measurement,analysis and performance evaluation”,“internal audit”,and “training and education”,so that the illegal operations could not be effectively controlled.(5)The deficiencies in “training and education”,“management review”,“leadership and commitment”,“hazard identification and assessment of risks and opportunities”,“monitoring,measurement,analysis and performance evaluation”,“laws and regulations and other requirements”,and “internal audit” are the most common safety management system failures in HCAs.The flaws in “training and education”,“management review”,and “leadership and commitment” occurred in all of the 65 accident organizations,while more than 50% organizations were involved in the flaws related to “hazard identification and assessment of risks and opportunities”,“monitoring,measurement,analysis and performance evaluation”,“laws and regulations and other requirements”,and “internal audit”.The common failures related to these elements in two kinds of HCAs(i.e.,fixed location HCAs and transport-related HCAs)are as follows.(1)For front-line employees,they lack training on knowledge and skills related to their jobs,while for managers,they lack training on knowledge related to risk management,and both of them lack safety awareness training to ensure the compliance with laws and safety management system requirements.In fixed location HCAs,the counts of inadequate training on knowledge and skills related to jobs and on safety awareness accounted for 91% of the total flaws in training programs for front-line employees,compared with 84% in transport-related HCAs.94% of the organizations did not establish training programs for managers on risk management in fixed location HCAs,and 42% of the all organizations lacked safety awareness training programs;while in transport-related HCAs,the proportions of organizations which involved in these two kinds of deficiencies in training programs were accounted for 92% and 54% respectively.(2)All of the organizations lack programs to review the effectiveness of safety management systems.As for issues in “management review”,all of the 65 organizations did not establish programs for top management to review the safety management system continued effectiveness,which made it impossible to determine whether the risk had been addressed by safety management systems and the intended outcomes had been met.(3)As for the deficiencies in risk assessment procedures,organizations should establish procedures to assess the risks in the system and procedures for job safety analysis.In fixed location HCAs,there were 49 organizations had deficiencies in the risk assessment procedures.The counts of flaws in these two kinds of procedures(i.e.,systematic risk assessment procedures and job safety analysis procedures)were accounted for 71% of the total flaws in all kinds of risk assessment procedures.In transport-related HCAs,all of the organizations had deficiencies in risk assessment procedures,and 69% of the total flaws were related to systematic risk assessment procedures and job safety analysis procedures.(4)It is important for HCA prevention to establish a procedure to evaluate compliance with legal requirements.For “monitoring,measurement,analysis and performance evaluation”,the most common deficiency in two kinds of HCAs was the absent procedure for evaluating the legal compliance.In fixed location HCAs,there were 36 organizations,accounted for 69% of the total,did not establish this procedure;while in transport-related HCAs,this proportion was 54%.(5)For two kinds of HCAs,there exist failures related to internal audit programs for “training and education” and “organizational roles,responsibilities and authorities”.For two kinds of HCAs,the two most common flaws in “internal audit” were the organizations did not establish programs to audit the implementation of requirements in “training and education” and “organizational roles,responsibilities and authorities”.In fixed location HCAs,there were 35 organizations which had internal audit issues,and 63% and 51% of them did not establish the internal audit programs for two system elements,i.e.,“training and education” and “organizational roles,responsibilities and authorities”,respectively.In transport-related HCAs,8 organizations had flaws in internal audit programs,and the number of organizations which failed to implement the internal audit programs for “training and education” and “organizational roles,responsibilities and authorities” were all accounted for 38% of the total.(6)For accidents of hazardous chemical road transportation,the significant safety management system failures are absent procedures to have access to technical standards for vehicles and safety accessories and absent procedures to ensure vehicles and safety accessories are complied with requirements in technical standards.In accident samples,there were 7 organizations involved in the business of hazardous chemical transportation,however,5 of them did not establish such two procedures.The absence of these two procedures indicated that there existed flaws in “laws and regulations and other requirements” and “mechanical integrity”. |
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