Statistics show that 95% of hazardous chemicals in China are involved in long-distance transportation, and road transportation accidents caused by this account for 30% -40% of the total number of hazardous chemical accidents. Tank trucks transporting hazardous chemicals account for the vast majority of them. Once a hazardous chemical tanker transportation accident occurs, emergency rescue and disposal should be carried out according to the following procedures and measures, and the following precautions and protective requirements should be implemented during the disposal:
1、 Disposal process
2、 Disposal measures
The materials transported by hazardous chemical tank trucks mainly include two categories: gases and liquids. In the event of a road transportation accident, it is highly likely to cause leakage or fire and explosion.
（1） Emergency response measures for gas leakage
1. Investigation and testing: Inquire with insiders or use instruments and equipment to detect the concentration and range of leaked gases. Manual inspection, unmanned equipment inspection, or a combination of both can be used for inspection.
2. Evacuation and explosion prevention: Use exhaust equipment such as smoke fans and exhaust trucks to disperse steam clouds gathered in low-lying areas, trenches, etc., and suppress the formation of explosive mixtures.
3. Combination of prevention and control: For gases with lighter specific gravity compared to air density, water curtains should be installed around the leakage point to prevent the leakage area from expanding. Robots, mobile cannons, water guns, and other water jets should be used to control and protect key areas behind the water curtain; For gases with a higher specific gravity, robots, mobile cannons, water guns, and other spray devices are used to control and protect the water flow in front of the leakage point. Water curtains are set up in the direction of attack and low-lying areas to block the spread of leaked gases to safe areas; For those stored and transported in liquid state and leaked in case of accident, foam coverage can be carried out first to slow the rate of vaporization and volatilization, so as to buy time for further emergency disposal.
4. Blockage and risk elimination: If the accident vehicle has the conditions for valve shut-off and material cut-off, under the guidance and assistance of technical personnel, firefighters can use misty water cover to complete the valve shut-off and material cut-off disposal; If the accident vehicle meets the conditions for plugging, a plugging plan shall be formulated, appropriate plugging tools shall be selected, and elite personnel shall be dispatched to complete the plugging operation under the protection of misty water.
5. Tank transfer: If the accident vehicle has the conditions for tank transfer, firefighters should use robots, mobile cannons, water guns, etc. to spray mist like water to protect professionals from pouring leaked materials from the accident tank into the unloading tank through static pressure high difference method, compressed gas pressurization method, or explosion-proof transfer equipment.
6. Control burning and exhaust: If the accident vehicle has the conditions for drainage and control burning, elite forces shall be dispatched to provide cover for professional personnel or, under the guidance of professional personnel, connect pipes and nozzles to transport the leaked gas to a safe area for ignition and control burning. For natural gas and other gases, they can also be diverted to a safe location and disposed of by setting up water curtains or under the protection of flowering jets.
7. Warning and evacuation: Clearly define the safe evacuation route and assembly point after evacuation, set up on-site safety observers, issue safety warnings in a timely manner according to changes in safety risks at the rescue site, and after personnel arrive at the assembly point, they should be counted and reported in a timely manner.
（2） Emergency response measures for gas leakage and fire
1. Based on the actual situation at the accident site, following the principles of "controlling combustion, preventing diffusion, and safe disposal", unmanned equipment such as robots and remote-controlled water guns (cannons) are selected to spray water flow to control the ignition point and maintain stable combustion, reducing the number of people in front. Strengthen the protection of nearby vehicles and facilities by using barrier water guns, water curtains, water hoses, and other equipment to block the spread of fire.
2. Cooling and fire control: When the tank of the accident vehicle is damaged, leaked, and catches fire, fire detection robots, mobile guns, water guns, and other equipment are used to spray flower or mist water to evenly cool the ignition point of the tank, reduce the internal pressure of the tank, and control combustion.
3. Isolation and protection: Water guns, cannons, or curtains can be installed between the burning tanker truck and key areas threatened by the fire to reduce the threat of thermal radiation.
4. Valve shut-off and material cut-off: If the accident vehicle meets the conditions for valve shut-off and material cut-off, with the guidance and assistance of technical personnel, firefighters can use misty water cover to complete the valve shut-off and material cut-off disposal.
5. Sealing and hazard elimination: If the accident vehicle has the conditions for sealing, a plan should be formulated and fully prepared. Each group of personnel should be responsible for fire extinguishing, protection, and sealing in detail, equipped with appropriate tools, equipment, and protective gear. After extinguishing the fire, elite personnel should be quickly dispatched to complete the sealing operation under the protection of misty water.
6. Tank transfer: If the accident vehicle has the conditions for tank transfer, it should cooperate with professional personnel to transfer the leaked material from the accident tank to the unloading tank through static pressure high difference method, compressed gas pressurization method, or using explosion-proof transfer equipment.
7. Warning and evacuation: Clearly define the safe evacuation route and assembly point after evacuation, set up on-site safety observers, issue safety warnings in a timely manner according to changes in safety risks at the rescue site, and after personnel arrive at the assembly point, they should be counted and reported in a timely manner.
（3） Emergency response measures for liquid leakage
1. Investigation and testing: Using instruments and equipment to detect the concentration and range of volatile gases in leaked substances. Manual inspection, unmanned equipment inspection, or a combination of both can be used for inspection.
2. Covering and explosion suppression: use fire-fighting detection robots, mobile guns, water guns and other equipment to spray foam, cover and protect the leaked and flowing materials on the ground, and prevent explosion.
3. Embankment diversion: Adopt methods such as embankment construction or trench excavation to limit the diversion of leaked materials to a safe zone and prevent the expansion of the hazard range.
4. Blockage and risk elimination: If the accident vehicle has the conditions for valve shut-off and material cut-off, under the guidance and assistance of technical personnel, firefighters can use misty water cover to complete the valve shut-off and material cut-off disposal; For those who meet the conditions for plugging, develop a plugging plan, select appropriate plugging tools, and dispatch skilled personnel to complete the plugging operation under the protection of misty water; For underground drainage, telecommunications, power supply pipelines, underground wells, etc., sand coverage, sandbag filling, foam injection and other methods can be used to block, to prevent leakage of liquid into.
5. Collection and adsorption: Use explosion-proof pumps, oil absorbing felt, etc. to collect and recover leaked liquids, and hand them over to professional personnel for disposal.
6. Tank transfer: If the accident vehicle has the conditions for tank transfer, it should cooperate with professional personnel to pour the leaked material from the accident tank into the unloading tank through static pressure high difference method or using explosion-proof transfer equipment.
7. Warning and evacuation: Clearly define the safe evacuation route and assembly point after evacuation, set up on-site safety observers, issue safety warnings in a timely manner according to changes in safety risks at the rescue site, and after personnel arrive at the assembly point, they should be counted and reported in a timely manner.
8. Anti toxic cleaning: When dealing with toxic and corrosive material leaks, on-site personnel should wear appropriate personal protective equipment for the hazards. After the accident disposal is completed, personnel and equipment should be washed and disinfected.
（4） Emergency response measures for liquid leakage and fire
1. Make decisions as the case may be: according to the water source situation at the accident site, follow the principle of "control first, then extinguish", select appropriate fire extinguishing equipment, control the fire and put out the fire, dike the flowing fire on the ground, and use foam and dry powder to put out the fire.
2. Fire extinguishing and cooling: When the tank of the accident vehicle is damaged, leaked, and catches fire, if the water source is sufficient and has the conditions for extinguishing the fire, use firefighting investigation robots, mobile guns, water guns, and other equipment to concentrate efforts on extinguishing the fire. If there is a flowing fire on the ground, the ground should be cleaned first before extinguishing the tank fire. For flammable liquids that can be dissolved in water or partially dissolved in water, fire-resistant foam, dry powder and other fire extinguishing agents shall be selected for firefighting.
3. Step by step propulsion: For multiple tank trucks catching fire or forming large ground flows, the front-line combat personnel should wear fire-resistant and heat-insulating clothing, use unmanned equipment or shelters to set up gun (artillery) positions, divide into several combat teams, alternate protection, and push in steps from outside to inside and from back to front to extinguish the fire.
4. Blockage and risk elimination: If the accident vehicle has the conditions for valve shut-off and material cut-off, under the guidance and assistance of technical personnel, firefighters can use misty water cover to complete the valve shut-off and material cut-off disposal; If there are conditions for plugging, a plugging plan should be developed in advance, and appropriate plugging tools should be used immediately after extinguishing the fire. Skilled personnel should be dispatched to complete the plugging operation under the protection of misty water.
5. Tank transfer: If the accident vehicle has the conditions for tank transfer, it should cooperate with professional personnel to pour the leaked material from the accident tank into the unloading tank through static pressure high difference method or using explosion-proof transfer equipment.
6. Warning and evacuation: Clarify the safe evacuation route and assembly point after evacuation, set up on-site safety observers, issue safety warnings in a timely manner according to changes in safety risks at the rescue site, and after personnel arrive at the assembly point, they should be counted and reported in a timely manner.
7. Anti toxic cleaning: When dealing with toxic and corrosive material leaks, on-site personnel should wear appropriate personal protective equipment for the hazards. After the accident disposal is completed, personnel and equipment should be washed and disinfected.
3、 Precautions
1. Emergency response personnel and vehicles should enter the site from the upwind or side upwind direction, and maintain an appropriate safe distance from the leakage point. The battlefield should not be set in low-lying areas.
2. Frontline personnel participating in emergency response and firefighting operations should wear appropriate protective clothing and gas defense equipment according to the hazard of materials and the threat of fire, and take personal protective measures.
3. In case of sudden danger during emergency response, on-site personnel should evacuate from the upwind or side upwind direction.
4. The investigation and inspection team shall not be less than 2 people, and the investigation and inspection work shall be integrated throughout the entire emergency rescue process.
5. In emergency response, efforts should be made to minimize the number of personnel in the front line. If conditions permit, unmanned equipment should be used to replace personnel and reduce safety risks.
6. In the event of accidents involving compressed gas or liquefied gas tanker trucks, it is prohibited to spray water onto safety accessories such as safety valves and tanks to prevent secondary accidents caused by freezing failure of safety accessories or increased pressure inside the tank.
When emergency personnel cool down a burning tank, no white spots should be left to prevent the tank from breaking.
8. It is strictly prohibited to extinguish open flames without proper preparation for on-site leak sealing.
9. It is prohibited to use direct current water to expose toxic and corrosive substances, in order to prevent splashing and injury.
10. After washing, the liquid should not be discharged arbitrarily and should be collected by professionals for harmless treatment.
4、 Protection requirements
According to the basic characteristics of transported materials, there are mainly safety risks of poisoning and explosion at the accident site after a leak occurs.
For sites with toxic substances, the delineation of toxic areas is generally based on the degree of damage caused by toxic gases to human health, and is divided into three areas: mild danger zone, moderate danger zone, and severe danger zone.
For sites containing explosive substances, the delineation of hazardous areas is generally based on the lower explosive limit, divided into three areas: mild hazardous area, moderate hazardous area, and severe hazardous area.
When emergency response personnel enter toxic or explosive hazardous areas and carry out emergency rescue and disposal work, they should select and wear necessary protective equipment according to different risks and levels, and do a good job in corresponding safety protection.
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