| Liquid ammonium,a chemical raw material and cooling agent,is wide used in petrochemical,fertilizer and food production industries.Among the many ammonium leakage accidents over the past few years,a big number of them happened in food production enterprises.70% of the new cold storage facilities that were built in recent years use ammonium as agent.However,food companies are not considered chemical enterprises and as a result,their safety equipment,safety management and supervision measures have lagged behind the spread of cooling storage,leading to increased occurrence of leakages.Therefore,studying the causes of such accidents and measures to prevent them carries substantial significance.Analysis of current literature on ammonium leakage accidents revealed that most of the research at home and abroad focused on the conditions of the accidents and rarely on human behavior that contributed to the accidents.In fact,however,ammonium leakage accidents can be attributed to a large extent to human behaviors.The 2-4 model for accident causation zeros in on the human factors in accidents,and although it was mostly adopted in the beginning to analyze mining accidents,it is now applied in accident analysis in multiple fields.Therefore,this paper will adopt the 2-4 model to identify the causes of ammonium leakages in China's food enterprises and their impact pathways.The 121 ammonium leakages that happened in food companies in China over 2007-2016 are used as case study.First of all,with the location of the leakage points as the basis of categorization,accidents are categorized as liquid ammonium leakages from storage and transportation(28),from pipelines(52)and from refrigeration equipment(41).Secondly,with the 2-4 model as theoretical basis and analysis method,the paper delves into the unsafe acts,unsafe conditions,habitual behavior and inadequate safety management system at play for each category of accident.In terms of unsafe behaviors,a list is compiled consisting of the unsafe behaviors in the accidents analyzed together with their impact pathways and violations of relevant regulations.A list of unsafe conditions is also made.As to habits,correlations are made between employees' habits and unsafe behaviors and conditions,shedding light on the unsafe habits of employees and safety knowledge they usually lack.For safety management system,it is analyzed from 3 angles – safety guidelines,safety management organizational structure and safety management procedure.The main conclusions are as follows:(1)The research above points to an accident analysis approach with the 2-4 model as theoretical basis.The approach has 8 steps:(1)Identify accident(2)Dissect organization(3)Analysis accident process(4)Investigate employees' unsafe acts(5)Study unsafe conditions(6)Explore habitual behaviors(7)Examine inadequate safety management system(8)Analyze impact pathways of all the causes.A total of 121 ammonium leakage accidents in China over 2007-2016 are covered by this paper.The results are shown in Annex 1,which validate the validity of this approach in examining ammonium leakages.(2)Ammonium leakages keep happening every year.From 2007-2012,the number of accidents declined with fluctuations while it went up after 2012.The number of deaths also dropped from 2007-2016 with the exception of 2013(which saw 4 major leakages with big casualties – 147 deaths in total).The number of ammonium poisoning accidents(111)is far bigger than that of explosions(10),but the latter claimed far more lives(128)than the former(69).Most of these accidents are categorized as general accident,rather than serious or major accidents.(3)With the information diffusion model,this paper calculates the probability of such accidents in each province every month based on the data of when and where the accidents happened.There are 5 months with a probability of over 50%-August(81.1%),July(74.2%),May(71.7%),April(68.2%),September(63.8%),June(58.4%)and October(52.1).These months are crucial for accident prevention.The top 5 provinces most at risk with at least one accident a year are Shandong(70.8%),Sichuan(58.3%),Zhejiang(49.2%),Anhui(45.1%)and Shanghai(44.8%),which should pay special attention to the prevention of ammonium leakages.(4)Through the analysis of ammonium leakage accidents in storage and transportation facilities,this paper has identified 32 unsafe acts that contributed to the accidents.The most frequent one among the direct triggers of accidents is failure to check facilities on time or control liquid level and pressure in the tank car or storage tank(7 times)and failure to check tightness of junctions before loading and unloading(7 times).Tolerating or ignoring violations in day-to-day operation and failure to organize safety training affect employees' habitual behavior,and the unsafe act of not formulating an operating procedure for storage and transportation results in an inadequate safety management system.Among the 15 unsafe conditions,the most common one is looseness at the junction of pump and pipeline(8 times),absence of protective gear(4 times)which will cause more losses.As to habits,the most common one is the lack of safety awareness(99 times),followed by insufficient safety knowledge(96 times).The main points of such safety knowledge are the necessity of safety training(21 times)and the importance of safety check(18 times).In terms of safety management system,there are 9 inadequacies,primarily about failure to set up or execute as required a safety training system(26 times)and safety inspection system(24 times).(5)Through the analysis of ammonium pipeline leakage accidents,this paper has discovered 36 unsafe acts that lead to the accidents.The one that caused the biggest number of accidents is irregular inspection of pipeline and other components(39 times).The unsafe acts in pipeline repair and installation lead to more accidents.As to violations,incompliant operation(103 times)and guidance(78 times)are the most common,accounting for 40.4% and 30.6% of total unsafe acts.In terms of unsafe conditions,there are 10,with aging pipeline and other parts and components appearing the most frequently(17 times)and absence of liquid ammonium leakage alarm(17 times).The latter makes it impossible for employees to realize the occurrence of leakage and thus tend to cause more severe damage.Among the habits,insufficient safety knowledge(123 times)and awareness(145 times)is the most problematic.Prominent among the 16 missing points of safety knowledge is the significance of safety check.For the safety management system,there are 9 inadequacies;and the failure of the safe production division to execute their duties of pipeline repair and management is the biggest culprit(42 times).(6)Through the analysis of ammonium refrigeration facilities leakage accidents,this paper has found 37 unsafe acts.The most common is the failure to check refrigeration facilities on a regular basis(35 times).Not wearing protective in ammonium operation area(27 times)usually results in more casualties.Among the unsafe acts at play,operation violations are the more frequent,accounting for 36.7% of all unsafe acts.As to unsafe conditions,refrigeration facilities with quality problems(19 times)appear the most often and has the closest connection to the occurrence of accidents.The unsafe conditions include incompliant conditions and dangerous conditions,making up 83.3% and 16.7% of total unsafe conditions.In terms of habits,lack of safety awareness(288 times)and knowledge(238 times)is the most liable.Among the 10 main points of safety knowledge,the most prominent is the necessity of inspecting liquid ammonium refrigeration facilities regularly and formulating and following operating instructions.For the 10 inadequacies of the safety management system,the most common is the failure of the safe production division to execute their duties facilities repair and management(37 times).The lack of safety management procedure is especially notable.(7)The analysis of these accidents indicates,over 80% of the unsafe acts leading to the accidents are operation violations.Incompliant conditions account for more than 70% of all unsafe conditions.The most common habit that constitute unsafe acts is insufficient dafety knowledge and awareness.Lack of safety awareness is usually because of inadequate safeyty knowledge.Therefore,enhancing safety training in companies can boost employee safety knowledge,reduce violations,thus reducing accidents.Based on analysis results,it is advisable to enhance safety knowledge training for drivers,freight guards,loading workers,the safe production division and their direct supervisors.The training for loading works and their instructors,in particular,shall focus on repair,maintenance and management of storage and transportation facilities,the importance of safety checks and compliance with operating instructions.To prevent pipeline leakages,safety knowledge training shall be provided to those working on the frontline(refrigeration workers,installation workers and repair workers),including complying with operation instructions,regular checking of pipelines and taking protective measures during operation.For their direct supervisors,safety education shall be provided to them emphasizing safety training for their subordinates and safety checks.At the same time,supervision shall be strengthened,correcting in time employees' unsafe acts to prevent the acts from becoming habits.As to preventing leakages from refrigeration facilities,safety training for refrigeration workers shall be enhance,mainly covering compliance with operating instructions,regular checking of facilities and starting or stopping the facilities strictly following operating procedure.Besides,emergency drills shall be carried out for fire or other emergencies to boost employees' capability of confronting crisis situations.For direct supervisors such as refrigeration shift managers and plant managers,safety education shall be provided on safety training for employees and safety supervision and inspection to help employees' form good working habits and reduce incompliant behaviors,thus reducing the likelihood of such accidents.This is the first time the 2-4 model is applied to the analysis of liquid ammonium accidents in food enterprises as theoretical basis for identifying the various reasons of such accidents and their impact pathways.This paper also put forward suggestions on safety training which can go a long way towards preventing such accidents. |
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