Analysis of Causes of Urban Gas and Pipeline Accidents

At present, with the implementation of the West-East Gas Pipeline in my country, urban gas pipelines have become more popular. Natural gas, liquefied gas, coal gas, and other gas pipeline networks have developed rapidly in my country. This is undoubtedly a good thing. It is a good thing for improving economic efficiency and reducing urban air pollution. , The convenience of residents’ lives, etc. bring benefits in all aspects. However, the various safety issues that follow have also brought people deep worries (such as pipeline natural gas, pipeline gas, pipeline liquefied gas, etc.). The gas pipeline is safe under normal circumstances, but under certain unexpected special conditions, such as improper construction, long-term disrepair of equipment, operating errors or other unforeseen reasons, the pipe network ruptures, etc., may cause the air to be broken. When entering the pipe network, the combustible gas in the downstream pipe becomes a premix with air and enters or partially enters the explosion limit. This has the necessary conditions to cause an explosion accident. In the prior art, no protective measures are applied to the meter, that is to say, all civil gas pipelines including urban pipeline gas and liquefied gas tanks do not have any tempering safety explosion-proof devices. In recent years, gas explosion accidents have occurred from time to time due to improper use of gas methods or failure of gas stoves or gas water heaters to cause backfire. The explosion of gas often causes the front control valve to fail, making it impossible to close at that time. As a result, a large amount of gas is ejected, causing personal injury or large-scale explosion accidents. At the same time, a large proportion of residents and catering industries in my country’s urban and rural areas use canned liquefied gas. Incorrect use of stoves, gas water heaters and other gas equipment or under special conditions will cause pressure relief valves and gas tanks when the liquefied gas stoves are tempered. The explosion brought misfortune to the family and society, and the situation is also very complicated and dangerous. Fire, leakage, and explosion accidents occurred in the process of production, transportation, storage and use in an endless stream. For example, at around 6:40 on January 27, 2003, a pipeline gas explosion occurred in a unit in Building 29, North District, Mingzhu District, Zhangqiu City, Shandong. Most of the entire unit was blown up. The 10 residents of the entire unit except for some individuals, All were buried under the blasted rocks, causing many deaths; on September 7, 2003, a gas meter explosion occurred at No. 2, 4th floor of a unit in No. 29, West Tower District, Shenyang City, killing 1 person and injuring 7 others. On September 17, 2003, the gas meters in the homes of four residents on different floors of a unit at No. 139, Hongwei Road, Taiping District, Harbin City suddenly exploded. When the air enters the pipeline, the residual gas combines with the air to produce an explosive condition. When other residents turn on the gas again, the gas will explode and the meter will be destroyed. Another example is the explosion of a gas meter in room 406 of a building in Mochou Garden, Nanjing in October 2003, which injured a man. At about 6 am on August 16, 2004, the commander of the social housing in Xihongmen Town, Daxing District, Beijing Two large gas tanks in the canteen suddenly exploded, causing another three gas tanks to catch fire. Beijing Youth Daily reported that gas broke out on the 5th floor of a residential building in Qingxiuyuan Community, Changping District, Beijing at 17:53 in the evening on August 20, 2004. The canister exploded. One person was injured and the other was trapped. The Changping Fire Squadron dispatched 5 fire trucks to the scene to fight the fire. This caused huge losses to the country and the people’s lives and property, and also brought great negatives to the public safety and stability of the society. Influence. In short, gas explosions are not uncommon in recent years. If the national high-tech product-new domestic gas pipeline flame arrester can be installed in the gas pipeline network or appropriate parts of the gas tank, so that the deflagration or detonation flame is quenched at the flame arrester, the flame can be prevented from spreading and the major accidents mentioned above can be prevented. Occurrence, further improve the safety of the use of gas pipeline network or gas tank equipment, and eliminate the accident at its initial stage. Of course, there are other factors that cause gas explosion accidents, but in many cases, flame arresters can play an irreplaceable role. From an economic point of view, flame arresters play a role in protecting the safety of gas equipment and people’s lives and property. Compared with its low price, it is also very worthwhile to install and use. Because the cost of a flame arrestor is only a very small percentage compared to the total equipment of each gas user, and it is even more insignificant compared to the loss caused by an explosion accident. At present, some industrial and developed countries abroad produce and use various industrial and civil flame arresters for the absolute safety of gas equipment and personnel. This article discusses the characteristics of urban gas fires and the causes of accidents in combination with the current status of gas. 1. The main nature of city gas and the characteristics of fire accident 1. Easy to spread. Diffusion refers to the diffusion ability of substances in air and other media. The diffusion ability of gas depends on two main factors, density and diffusion coefficient. The stronger the gas diffusion ability, the faster the fire spreads, and the fire burning area will expand accordingly. 2. Easy to shrink and expand. City gas has obvious compression and expansion properties, and follows the law of PV=NRT. Natural gas and coal gas are usually transported and supplied by pipelines, with pressures ranging from 0.1 to 0.45 MPa, and generally should be less than 0.01 MPa when entering the home. However, most of liquefaction enters users’ homes in bottles. The cylinder pressure is usually around 0.1 MPa. In the event of a fire accident, the danger is far greater than that of pipeline gas. 3. Flammability. The minimum ignition energy of the three types of gas is relatively low, and the range is between 0.19 and 0.28 mj. The flame spreads faster. 4. Easy to explode. In gas fire accidents, more than half of gas fires are first caused by explosions. The wider the explosion range, the lower the lower limit concentration, and the greater the fire risk. For example, the explosive concentration of natural gas is 5%~15%, the liquefaction is 2%~14%, and the concentration is 6%~72%. Their fire hazard is natural gas <liquefaction <. 2. Causes of urban gas fire accidents 1. Piped gas The main gas sources that use pipelines to supply gas are natural gas and coal gas. This method of gas supply equipment usually consists of pipelines, gate stations, high-pressure stations, pressure regulating devices and auxiliary equipment on the pipelines to form a pipe network system. Because the pipeline is a concealed project, changes in the earth’s crust, aging of the pipeline, and other unforeseen reasons can cause air to enter the pipe over time. The carrier medium itself is flammable and explosive, and is in a certain pressure state, so it has greater The risk of fire. Pipeline gas explosion accidents occur more frequently in my country every year. Analyze the main reasons for the following three aspects. (1) The pipeline equipment is aging and corroded seriously. Some pipelines have not been inspected and repaired after decades of use, and their safety and reliability cannot be determined. In many cities, with the needs of urban construction, the location of local pipelines has changed, and roads have been widened and the gas pipelines have been placed under the lanes, which can easily cause pressure damage to the pipelines and gas leakage. In addition, the loose connection of valves and flanges will also cause medium leakage. (2) The pressure relief devices, rupture disks, and explosion-proof membranes on the carrier equipment do not work, and the electrical equipment in the hazardous area is not explosion-proof, non-lightning, anti-static, or does not work although there are. (3) Failure to implement safety responsibilities and management measures, failure to implement safety organization and rules and regulations, violation of operating procedures, etc. 2. Common causes of fire and explosion accidents in bottled gas (1) Overfilling. That is, more than 85% of the volume of the cylinder. At this time, if the bottle body is affected by external factors, it is prone to rupture, causing the liquefied gas to leak and spread rapidly. (2) The bottle body expands when heated. Because liquefied gas is more sensitive to temperature effects. When the temperature rises from 10 degrees Celsius to 50 degrees Celsius, the vapor pressure increases from 0.64Mpa to 1.8Mpa. If it continues to rise, it will cause the bottle to explode. (3) The bottle body is corroded or impacted, causing damage to the bottle body and causing fire and explosion accidents. (4) The gas cylinder angle valve and its safety accessories are not tightly sealed, causing air leakage. (5) Air enters into the cylinder, and if it is used, no residual air is left, which will cause air to enter the cylinder. It may cause the cylinder to explode when it is refilled next time. 3. Human factors (1) Carelessness, forgetting to close the valve or not closing the valve tightly when the personnel leave the kitchen for a long time, resulting in a large amount of gas leakage. (2) Making operational mistakes, being accustomed to “using gas to wait for fire” and not complying with “using fire to wait for gas”; resulting in gas leakage before ignition. (3) When replacing the liquefied gas cylinder, the user does not carefully check whether the ○-shaped rubber ring of the pressure regulator is aging and falls off or the handwheel thread is connected incorrectly. (4) Lax management, illegal storage, and improper use. Especially some hot pot restaurants. (5) The professional quality of the operators engaged in gas operation is not high. Some personnel take up their posts without training or do not receive regular training. Little is known about gas fire safety, and there is no ability to detect hidden safety hazards or even illegal operations. 3. Specific measures to ensure the safe use of gas 1. Strict planning and coordination The gas management project is a basic project of the whole society, which objectively requires the close cooperation of planning, urban construction, municipal, labor, power and telecommunications, and firefighting departments. When planning the urban development plan, the planning department must fully listen to and demonstrate the development plans of the municipal, telecommunications, power and other departments, and invite experts from various departments to “consult” when necessary, so as to formulate objective, practical and scientific plans, and implement new installations. Household pipeline gas explosion-proof flame arresters and other devices enable the construction of urban gas pipelines to develop normally while ensuring safety first. 2. Strictly select materials and strictly control the quality of the project. Before construction, labor and technical departments must jointly conduct and test the selected pipe equipment, especially the materials that will be used for high-pressure pipelines. And in the design, each pipeline gas user terminal installs a household pipeline gas explosion-proof flame arrestor device. If there is any phenomenon that does not follow the original design drawing during the construction, it must be resolutely stopped and the responsible person should be punished. When the project is accepted, the planning, urban construction, labor, and fire protection departments must resolutely rework the sections that do not meet the requirements, and seriously deal with the responsible persons. Only in this way can the inherent hidden dangers of gas pipelines be eliminated in the bud. Ensure the safety of people’s livelihoods and property. 3. Establish and improve various systems and strengthen later management. Strengthen the study of relevant laws and regulations and technical standards, raise awareness, overcome the ideology of emphasizing use and neglecting management, and enhance safety awareness. Establish a rigorous and feasible management system and working procedures, and implement the post responsibility system. Formulate and improve various management systems related to the design, installation, use, inspection, and transformation of gas pipelines. For new gas pipelines, the government requires gas investment developers to install new household pipeline gas explosion-proof firearms at each gas user terminal. Although gas companies have increased some costs, they have improved safety. 4. Strengthen publicity and education In recent years, the publicity in this area has been insufficient. Many people do not even know the dangers of gas pipelines. There are also some industry units that do not know enough about the tempering explosion of gas pipelines. Many families are shrouded in potential explosion hazards due to his negligence. The main reason for this phenomenon is that publicity and education are not strong enough, deep enough, and not broad enough. Therefore, it is necessary to vigorously do a good job in safety education, adopt various forms such as printing publicity pictures, broadcasting TV news, and holding safety knowledge contests, so that people use gas and raise fire protection awareness and pay attention to fire safety.