Pay attention to the safety management of hazardous work areas in confined spaces

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　According to the definitions provided by relevant authorities, a confined space is a space of certain size into which workers can enter to carry out designated tasks, but whose entrances and exits are narrow or in which the space is relatively enclosed or semi-enclosed； When workers enter this area, they are at risk of oxygen deficiency or poisoning by toxic and harmful gases such as hydrogen sulfide, carbon monoxide, carbon dioxide, methane, and hydrogen cyanide ； Places where there is a risk of gas (dust) fires and explosions. 　　In daily construction activities, production inspections and maintenance tasks, people often find themselves working in confined spaces. When working in such spaces, even the slightest carelessness can lead to accidents such as gas poisoning or suffocation, fires, or explosions, resulting in casualties and property damage. Moreover, attempts at rescue carried out blindly after an accident often cause the situation to worsen further. Such accidents occur from time to time across the country and account for a certain proportion of all accidents; the lessons drawn from them are extremely profound, and they require our utmost attention. 　　I. Basic scope of hazardous work in confined spaces In construction, municipal engineering, decoration, foundation work, or in factory workshops where tasks such as installation, inspection/maintenance, welding, painting, and anti-corrosion treatment are carried out, the following types of locations constitute confined space hazardous work areas: 1. Enclosed or semi-enclosed equipment: such as ship holds, storage tanks, reaction towers, refrigerated trucks, caissons, as well as boilers, pressure vessels, buoy tanks, pipelines, and tank cars. 　　2. Underground confined spaces: such as underground pipelines, basements, underground warehouses, underground structures, hidden ditches, tunnels, culverts, pits, mines, abandoned shafts, cellars, biogas digesters and septic tanks, sewers, ditches, wells, ponds, building pile holes, underground cable trenches, etc. 　　3. Above-ground confined spaces: such as storage rooms, wine vats, fermentation tanks, waste disposal sites, greenhouses, cold stores, grain silos, enclosed workshops, laboratories, flue ducts, etc. 　　II. Accident Cases: 1. Gas poisoning incident involving municipal pipelines On the afternoon of July 4, 2004, at 6 p.m., a municipal company in Cixi City, Ningbo, suffered a hydrogen sulfide poisoning accident while removing the pipe barrier at the junction of the newly built manhole and the existing sewage collection well at the intersection of South Second Ring Road and Yingxiong Road. The manhole has a diameter of 1.2 meters and a depth of 6 meters. First, a worker went down to drill a hole in the blocking wall; after creating a hole of about 10 cm, another worker was sent down to continue the drilling. As soon as the second worker reached the bottom of the manhole, he fainted due to poisoning (it is estimated that a large amount of toxic gas accumulated in the previously sealed pipeline had escaped at that point). Upon seeing this, the people on the ground took no protective measures and rushed into the well one after another to rescue others; as a result, one after another they collapsed, with a total of 4 people falling. Due to the force of the pressurized sewage, 3 of the poisoned workers were swept to another manhole, while another worker got trapped between the pipes of the two manholes. Due to the prolonged rescue time, all four individuals died after being taken to the hospital. 　　2. Poisoning accident during manual hole-digging pile construction On June 16, 2001, a gas poisoning accident occurred at a construction site of a pharmaceutical factory in a development zone, carried out by a construction company in Chuxiong, Yunnan. The diameter of the pile hole in this accident was 1 meter, with a depth of 10.5 meters. After the rebar cage was placed in the pile hole, one of the workers went down into the hole to remove the reinforcing steel pipes used to prevent the cage from deforming. When the worker reached a depth of about 6 meters in the well, he encountered a high concentration of carbon dioxide inside the hole, which caused him to suffer from poisoning and suffocation and fall to the bottom of the hole. At that time, three people on the ground descended into the well blindly without taking any precautions in order to carry out rescue efforts, and all of them fell to the bottom of the well and died ； Three more people went down; although no deaths occurred, they suffered poisoning injuries of varying degrees. Finally, the people were rescued only after measures such as ventilation were taken, but this resulted in a serious accident in which 4 people died and 3 were seriously injured.