【Accident Case Analysis】08: Learning Preventive Measures for Hazardous Chemical Accidents through Case Studies

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1. Employees must be familiar with the basic safety regulations for chemical handling. 【Accident Case】On July 16, 2010, an explosion occurred in the oil pipeline of the crude oil depot owned by Dalian CNPC International Storage and Transportation Co., Ltd., located in the free trade zone of Dalian City, Liaoning Province. This led to a massive fire and a significant spill of crude oil; some of the crude oil, as well as the pipelines and equipment, were damaged in the incident. Additionally, some of the spilled crude oil flowed into nearby waters, causing pollution. The accident resulted in minor injuries to 1 worker and 1 person missing ； During the fire fighting, 1 firefighter lost their life and 1 was seriously injured. The direct property damage caused by the accident amounted to 223.3019 million yuan. The direct cause of the accident was the continued filling process while the oil tanker had stopped unloading oil, which led to a local accumulation of \"hydrogen sulfide scavengers\" in the oil pipelines. This resulted in intense oxidation reactions, causing the pipelines to explode and leading to a fire and an oil spill. It violates the \"Six Strict Requirements for Operators\": strict implementation of the shift handover system, thorough routine inspections, and strict adherence to operating procedures and other regulations. [Basic relevant regulations] (1) The 41 Prohibitions for Chemical Enterprises; (2) Ten Regulations for Ensuring Production Safety in Chemical (Hazardous Chemicals) Enterprises; (3) Five Regulations for Safe Operations in Confined Spaces; (4) Six Regulations for Public Announcements on Enterprise Safety Production Risks; (5) Ten Regulations for Fire and Explosion Prevention in Oil and Gas Storage Areas; (6) Five Regulations for Preventing Dust Explosions in Enterprises. 2. Before carrying out special operations such as hot work or work in confined spaces, the approver must organize a hazard analysis together with the personnel involved in the operation, supervision, and related tasks. 【Accident Case】On May 29, 2010, a large chemical manufacturing company in Deqing carried out welding work on a water storage tank. Due to inadequate analysis, it was not taken into account that the tank was connected to pipes carrying propane, posing a risk of propane entering the tank. As a result, propane entered the tank during the welding work, leading to a flash explosion that caused one death and one injury. Lessons from the accident: The situation in which substances of type C can flow into storage tanks is better understood by the operators at the relevant work stations than by those carrying out welding tasks or acting as supervisors. When high-risk operations are conducted at a particular workstation, it is necessary to conduct a risk analysis together with the personnel working there and those involved in related tasks, in order to better prevent accidents. 【Cause Analysis】The main reasons for accidents in special operations at present are incomplete hazard analysis, lax oversight by approvers during the approval process, and inadequate implementation of safety measures. A considerable number of companies, when carrying out special operations, primarily rely on the safety measures listed in the operation permit for verification. The safety measures specified in the special approval forms are aimed at common issues; as for hazard analysis that takes into account the specific conditions of each company, it is necessary to conduct a detailed analysis based on those particular circumstances. Otherwise, the hazard analysis will be incomplete and the safety measures insufficient, which can lead to accidents. 【Preventive Measures】In light of the above situations and existing problems, the best approach is that, for special operations in hazardous positions, the approver must gather the workers involved, those working at the relevant positions, as well as other related personnel to conduct an analysis. This ensures a targeted and comprehensive approach, as the workers are best aware of the dangers specific to their own work areas. As for the other related personnel, it is necessary to consider the risks associated with the interconnected pipelines and shared work areas within chemical plants, so as to effectively avoid accidents resulting from incomplete risk analysis or inadequate preventive measures. 3. The operational positions must prepare a \"Table of Positional Risks and Control Measures\" which should be posted on the wall, and the personnel working in those positions must be proficient in it. 【Accident Case】On March 7, 2016, after a company in the city’s development zone finished loading cotton, it was preparing to load another batch. While moving the materials, friction between the woven bags and the ground generated sparks, which caused hazardous chemicals such as toluene to be released into the air, leading to a fire accident that had significant consequences. Lesson from the accident: The operators were unaware of the risk that hazardous chemicals emitted at their workstations could be ignited by sparks generated during the handling of materials ； An excessive amount of cotton dust piled up at the site blocked the emergency exits, allowing the fire to spread and creating a risk of difficulty for people to escape ； The dust cleaning process on site generated flying dust, posing a risk of dust explosion; no effective measures were taken, resulting in an accident. 【Cause Analysis】To accurately, comprehensively, and thoroughly analyze the hazards associated with a particular position, covering all employees, all aspects, and the entire process, it is necessary to draw on collective wisdom. Everyone has seen, encountered, or experienced the risks associated with their job to some extent, and thus has some understanding of them; however, this understanding is never complete. It’s like trying to understand an elephant by touching only its parts. Only by analyzing everyone’s insights, pooling collective wisdom, and integrating them together can a comprehensive and accurate \"Job Risk and Prevention Measures Table\" be created; otherwise, attention will be divided and important aspects will be overlooked. 【Preventive Measures】It is necessary to organize personnel from areas such as process management, safety, equipment and facilities, electrical systems, as well as workshop supervisors, team leaders, and employees, to analyze potential abnormalities in various aspects related to their respective positions—including equipment and facilities, process control, and operating procedures—and the corresponding countermeasures. Appropriate measures should be taken for each possible scenario, and a \"Job Risk and Prevention Measures Table\" should be prepared. Due to limited resources, companies can seek expert guidance. Through employee participation, expert oversight, and supervision by regulatory authorities, all employees can become familiar with the entire operational process of their roles, the operation of equipment and facilities (including functions such as water, electricity, and instruments), the key control points of the manufacturing processes, as well as how to handle various abnormalities and emergencies effectively. Only those working in relevant positions must master the \"Table of Positional Risks and Prevention Measures\" thoroughly, internalizing it in their minds and putting it into practice, so as to truly shift from passive prevention to proactive prevention. 4. The operation area must comply with standards on-site; employees should carry out their tasks in accordance with these standards, and management should enforce the relevant regulations. 【Accident Case】On July 16, 2015, during a liquid gas transfer operation at Shida Technology Company in Rizhao, Shandong, an explosion occurred due to improper operations, resulting in severe consequences. Lessons learned from the incident: It is strictly prohibited to adopt the process of pressurizing by water injection for tank transfer; instead, water injection alone should be used. Additionally, actions such as installing blind flanges on pipelines leading to flares in emergency situations violate relevant regulations. The operator fails to follow the prescribed procedures; they must not leave their post during the manual water cutting process, and must not leave their duty area without permission ； The on-site emergency shut-off valve cannot be controlled automatically ； In terms of management, no enhanced controls were put in place to address the aforementioned violations, nor was there proper supervision to ensure their implementation. 【Cause Analysis】The operation area must comply with standards on-site, employees must carry out their tasks in accordance with these standards, and management must follow the established procedures – these are the most basic and important safety requirements. Currently, many companies and work sites suffer from common problems such as materials being piled up in disorder, blocked passages, damaged pressure gauges on reaction vessels that go unattended, and expired fire extinguishers that are ignored. The employees on the job are aware of these issues but fail to recognize their potential hazards ； In terms of management, effective implementation is not possible due to the lack of standardized requirements for positions. At present, the biggest problem with regulation and management is not the lack of systems or regulations, but rather the lack of enforcement. 【Precautionary measures】Nothing can be accomplished without rules and standards. Shang Yang established trust by using a pole as an example, focusing on implementation to achieve practical results. The same is true for safety management; only by having rules to follow and adhering to them can such incidents be prevented. The \"Job Risk and Control Measures Table\" represents the standard requirements for each position, and these must be strictly implemented and carried out thoroughly. 5. Strictly implement self-inspections at the work post, team inspections, workshop checks, and factory-level supervision. 【Accident Case】The severe fire accident on June 27, 1997, at the tank farm of Beijing Dongfang Chemical Plant: A massive explosion and fire broke out at the plant’s tank farm, resulting in 9 deaths, 39 injuries, and direct economic losses of 117 million yuan. This is a rare and severe accident, both domestically and internationally. When transferring light diesel from railway tank cars to storage tanks via oil pumps, an operator opened the wrong valve, causing the light diesel to enter the fully loaded naphtha A tank. This led to a large amount of naphtha leaking out through the vent on top of the tank (about 637 cubic meters). The leaked naphtha and its vapors came into contact with an open flame during diffusion, resulting in the first explosion and fire, which in turn caused explosions and fires in other tanks in the tank area, including the ethylene tank. Lessons from the accident: If self-inspections are carried out at the work post, issues can be detected in a timely manner; team inspections can also help identify problems, allowing for prompt action that may effectively prevent accidents from occurring. Many hazardous chemical accidents occur due to laziness in carrying out inspections or inadequate inspection, which leads to such incidents. 【Precautionary measures】Employees in each position should conduct self-inspections on a regular basis, especially during shift changes and in the event of any emergencies. Team members should also carry out continuous inspections to identify any abnormalities promptly and take corrective action right away. The workshop should conduct inspections irregularly on a weekly basis, and these inspection results should be included in the evaluation system. The company should oversee the self-inspections by employees, the team inspections, and the workshop inspections, and announce any violations that occur. The four types of inspections work together, supervising and reinforcing one another. 6. Safety inspections should be quantified and linked to evaluations. 【Accident Case】A small private battery manufacturing company in Changxing established quantitative standards for every task and detail; for example, a fine of 10 yuan was imposed for each instance where the charging and discharging records were found to be incorrect or incomplete, and marks were placed on defective batteries which were then removed from use, with a fine of 20 yuan for each such defective battery found. This battery manufacturing company conducts random inspections on a weekly basis, publishes the results promptly each week, and links these inspections to employees’ salaries. As a result, employees are aware of the reasons for any deductions and reduced pay, allowing them to make timely corrections. This approach helps to change their passive attitude toward their tasks to one of proactive and voluntary compliance, thereby creating a positive cycle in which the workplace remains clean and orderly, employees follow the established procedures, and management operates according to rules and regulations. 【Cause Analysis】Many companies currently face the following issues in their implementation process: First, assessments are not conducted in a timely manner – they take place only once a year, which is too infrequent. As rewards are given only at the end of the year, there is little motivation among employees, and the results achieved are not significant ； Second, the assessment is not quantified, resulting in low operability ； Third, no incentive mechanism has been established, resulting in low enthusiasm among employees. 【Precautionary measures】Inspections must be quantified; only through quantification can evaluation be carried out, and evaluation is linked to rewards to ensure proper implementation. Only when the assessments are aligned with the goals to be achieved can efforts be directed effectively. The \"Job Risk and Control Measures Table\" should be taken into account, as well as ensuring that the work site complies with relevant standards, that employees operate in accordance with these standards, and that management follows established procedures. Regular checks should be carried out on a weekly basis, and rewards and penalties should be implemented accordingly. Only by persisting in this approach can these measures be effectively put into practice. 7. The number of personnel in hazardous work positions is strictly controlled to prevent major accidents. 【Accident Case】On November 28, 2007, an explosion occurred at a chemical manufacturing plant in Nanxun, resulting in a serious accident in which all 3 workers on the same work shift lost their lives. Lesson from the accident: A large number of people at the work site is a key reason for the expansion of the accident. 【Precautionary measures】Strive to reduce the number of workers in hazardous positions in order to lower the likelihood of serious accidents. Other measures such as automation, or enhanced inspections of work areas, can be employed to effectively reduce the likelihood of serious accidents resulting from crowd gatherings. 8. New employees working in positions involving flammable and explosive hazards (including maintenance) must possess the ability to identify such hazards, the skills for standardized operations, and the capability to handle emergencies appropriate to their role. They may only take up duties independently after passing a comprehensive assessment. 【Accident Case】In 2014, during trial production at an ink manufacturing company in Wuxing, a fire broke out due to static electricity generated by too fast flow rates while discharging materials. Lessons from the accident: The employees of this company were new hires; they were unaware of the risk of static electricity being generated due to too rapid material placement, and their handling methods were incorrect. After the accident, they were not familiar with the procedures for emergency response, which led to the accident from spreading further. 【Preventive Measures】Skills in risk identification and hazard detection and remediation: Fully understand the dangers associated with one’s job role and the factors that can trigger such risks; be aware of the hazards in the surrounding environment and their potential impact on oneself; comprehend the consequences of violating safety rules. Any identified hazards should be addressed promptly, so as to achieve the goal of preventing harm to oneself and others. Standardized operational skills: Be familiar with the correct operating procedures, master the procedures for using new processes, equipment, materials, and methods, and carry out operations in accordance with these standards; at the same time, be aware of the methods for dealing with abnormal situations. Emergency response skills: Mastering emergency handling, personal risk prevention, disaster avoidance, and self-rescue methods ； Being familiar with the use and maintenance of personal protective equipment and emergency gear enables effective handling of minor accidents and protects personal safety. New employees must undergo pre-job training, possess the aforementioned skills, and pass a comprehensive assessment before they can take up their positions, thereby effectively preventing accidents at the source. 9. Monitoring, automatic control, interlocking, alarm, and shutdown devices in key areas and hazardous locations must be in good condition, with dual-person oversight. 【Accident Case】The 4.22 explosion at a chemical logistics and warehousing facility in Jingjiang, Jiangsu, in 2016. 【Precautionary measures】Monitoring, automatic control, interlocking, alarm, and shutdown systems in key areas and hazardous locations meet relevant requirements and are in good condition; they enable effective prevention before accidents occur, and allow for remote control after an accident happens. In terms of personnel operation, a two-person control system is employed to prevent mistakes, particularly to avoid a repeat of the severe fire accident that occurred on June 27, 1997, at the tank farm of Beijing Dongfang Chemical Plant. 10. External construction workers must receive safety training before entering the site, and supervision and management must be strengthened during the construction process. 【Accident Case】In 2012, an enterprise in Wuxing, Huzhou City, suffered a poisoning accident in a confined space while hiring external workers to clean a sewage tank, resulting in 4 deaths. 【Cause Analysis】Since outsiders are not familiar with the hazards present in the company, they are prone to causing accidents. Many companies rely on signing responsibility agreements as a substitute for proper management, which leads to gaps in oversight. It is necessary to provide safety training to outsiders so that they are aware of the hazards and the measures needed to prevent them. 【Precautionary measures】External workers must receive safety training before starting work on site; in particular, supervision and management must be strengthened during the construction process to prevent accidents caused by illegal operations.