The reason of gas explosion should be understood first. The three steps of natural gas from leakage to accumulation to explosion limit, and then to ignition are indispensable.
1. There is a great possibility of air leakage in the three areas of pipeline socket, stove and plastic hose in domestic natural gas equipment.
The steam leakage of the pipe joint is mainly caused by the construction quality and the unauthorized disassembly and connection of the user. The steam leakage of the cooker is mainly caused by the quality problems of the cooker products. The steam leakage of plastic hoses is mostly caused by long-term non-disassembly or poor quality of plastic hoses. Most people always feel that they have not moved normally, and there is nothing wrong with their appearance after several years. This is a security risk.
2. In the category of explosion limit, it is said that natural gas leakage is not terrible, but the terrible thing is that the natural ventilation of the leakage site is not good, resulting in a closed space. This time is already very dangerous, so once it encounters a fire, the spark discharge will explode instantly.
So, if you smell natural gas leakage, don't turn on the light first! Second, don't make a phone call in the room, and retreat to a wide place to find help. The only very simple way to prevent gas explosion is to always open a window in the restaurant kitchen! After all, the density of natural gas is lighter than that of gas. As long as it is naturally ventilated, it will float out even if it leaks, and it is not easy to explode.
There are few overpressure explosions in long-distance pipelines, and generally there is leakage as long as it explodes. The main causes of leakage are corrosion and physical damage. The discharge of chemical waste and galvanic reaction with soil layer are the key ways of corrosion, and the most lacking part is welding. Moreover, the leakage of welding is usually the cumulative result of insufficient pressure resistance and erosion: the welding quality is not very good, and the pressure resistance and self-care ability at this point are poor. Coupled with erosion, compressed gas will immediately break the most missing point, resulting in leakage. There are also physical injuries. There are two key factors: natural disasters and human factors, geological structures, landslides, geological foundation settlement and local collapse, all of which may crush or wear the pipeline. There are two kinds of damage caused by human factors, one is direct damage and the other is indirect damage.
The direct damage is that some industrial equipment, such as excavators, drilling equipment, etc., immediately dries the pipeline, causing pipeline damage and leakage, or part of the pressure-resistant working ability is weakened, and then leakage occurs. The regulation of buried depth of pipeline foundation is that the minimum buried depth at the top of pipeline is 1.5m, which is easy to cause pipeline damage in engineering construction. Indirect damage is, for example, strong vibration caused by engineering blasting or engineering construction, which changes the distribution of in-situ stress on the pipeline, and may also lead to local damage or weak pressure resistance, and eventually lead to leakage.
Judging from the scale of the explosion at the scene, there must be a lot of gas deposition. As a city street in Xin Xu, if the road is silted, it may be unbearable for the residents who have suffocated. I think it may be the leakage of underground gas pipeline, and there must be enough indoor space underground to collect gas.
Due to the legacy of historical time, the gas pipelines in some big cities have been changed from the previous liquefied gas pipelines, and the moisture in the body has become dry gas, which has certain security risks. In addition, due to the material problem of the pipeline, the pig iron pipeline laid in the last century is buried underground, and how much erosion will occur after a long time is also a difficult point.
However, all gas companies have technical and professional safety inspection and line finding personnel. Such a safety accident will occur in Shiyan, which is inseparable from the dereliction of duty of safety inspection and line finding personnel of local gas companies. At the same time, some small gas companies have limited production capacity and insufficient staffing, which has caused some omissions (at this stage, we are not sure which gas company). Because of the shortage of overall strength and funds, some problems that are obviously fragile and urgently needed to be solved have not been solved for a long time. This situation has occurred all over the country, and there are also ups and downs of security risks.
First, the gas explosion limit range is 5% ~ 15%. If the concentration of natural gas in the air is within this range, it will explode immediately in case of fire, and it will always catch fire if it exceeds this range. So from the scene, it seems that the underground natural gas pipeline leaks, accumulates in the underground confined space, and then explodes in case of fire. I think it may be the leakage of natural gas pipeline, and some reasons (not keeping a safe interval during construction, not following the drawings, etc.). ), it fled to the sewage pipe in the downpipe (the enclosed space of these two pipes is very large, which meets the explosion standard) and poured into a street community. Someone threw a cigarette butt into the well and it exploded immediately.
I think this accident may be caused by the maintenance team: judging from the case clues published on the Internet at this stage, the explosion is probably the misfortune that many people did not follow the standard in the whole maintenance process.
1. It was the farmer's market that exploded, not the residential area.
Before the explosion, the gas company and firefighters were already at the scene, and the explosion was being processed.
At 5 o'clock in the morning, someone called the police to say that natural gas was leaking, but the maintenance team of the gas company was unclear in several aspects, and it was probably late.
4. Some netizens who know about the maintenance of the gas company posted a guess that the maintenance personnel are likely to make a mistake. For example, they didn't close the gate valve and set the warning according to the standard.
Firefighters probably made mistakes, for example, they didn't put out the fire immediately to evacuate the crowd.
6, death or injury, there should be a gas company or firefighters.
Property management also has certain obligations. The property management fee of the old house is far less than that of the new house, which is full of loopholes. For example, in an old community like a safety accident, I'm afraid there will be no property management services and services.
In addition, even if real estate companies and industry committees have responsibilities in China, their rights are far less than those of HOA. There are too many cases where gas is connected and used indiscriminately.
The explosion of pure shops in this safety accident is really good, but the scene is unique and the passenger flow is very large. If the lowest floor of residential area is changed to commerce for a long time, the loss caused by explosion will be higher.
But it's also hard to understand, as I said at the beginning. China has produced this solid logical thinking. You buy an old teaching area with a high age and charge you 5 yuan for property management, while the new community charges 2 yuan, which is unacceptable to anyone.
Moreover, in second-and third-tier cities and some long-term planning areas, the cost of pipe network transformation and renovation is too high, and there is no working ability at all. Moreover, many planning areas have been changed to gas, which is not as effective as the overall planning of various pipe networks in the new district. Many regional gas pipe networks have existed for more than ten years, and it is really impossible to maintain them foolproof.