Let’s review these safety basics once more

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This post was last edited by yinkuilin6868 on 2016-6-13 09:30. Safety in production: Flammable, explosive, toxic, and corrosive substances are often used in chemical manufacturing； Production operating conditions sometimes require high temperature and high pressure ； These factors pose a great risk to chemical production. In chemical production, safety must be given top priority; the principle of \"safety first, prevention first\" must be implemented! Check whether you have followed all the following safety procedures correctly; does your factory have all these safety measures in place? Precautions for safe startup/shutdown
1. Safe operation ★ Check and ensure that water, electricity, and steam (gas) meet the requirements for startup; all raw materials and supplies must be readily available and of acceptable quality. ★Check the opening/closing status of valves and the installation/removal of blind flanges to ensure unobstructed process flow in the unit. All mechanical and electrical equipment, as well as electrical instruments, must be in good condition. ★The equipment for heat retention, pressure maintenance, and cleaning must meet the requirements for operation; if necessary, it should be replaced, cleaned, and analyzed again to ensure it is compliant. ★Safety and fire protection facilities must be in good condition, and communication channels must be unobstructed. When starting up production units with high risks, the fire department and medical services should be notified to be present. ★During operation, it is necessary to strengthen communication between relevant teams, follow the steps outlined in the operation plan strictly, and adhere rigorously to the requirements regarding the rates of temperature and pressure changes as well as the rates of load increase and decrease. ★During startup, closely monitor process changes and the operating status of equipment. Any abnormalities must be addressed promptly; in case of an emergency, the startup must be halted. Forcing a startup under such circumstances is strictly prohibited. 2 Safe parking ★Normal parking must be carried out in accordance with the steps outlined in the parking procedure; the automatic parking interlock system designed for emergency situations should not be used for normal parking. ★The system’s pressure and temperature must be reduced by the required amounts (rates), following the sequence of reducing pressure first and then temperature. For equipment (containers) that require pressure or temperature retention, the changes in pressure and temperature must be recorded on schedule after shutdown. ★To shut down large-scale transmission equipment, the main machine must be stopped first, followed by the auxiliary machines. ★When the equipment (container) is depressurized, attention must be paid to the release and dispersion of chemically hazardous substances that are flammable, explosive, or toxic, in order to prevent accidents. The pressure relief operation should be carried out slowly; no disassembly shall be performed until the pressure has been completely released. ★Replace equipment containing toxic, harmful, flammable, and explosive gases. Gases commonly used for displacement include nitrogen and steam; nitrogen should be given priority as a displacing gas, since steam has a higher temperature. After displacement, a cooling tower is required to lower the temperature inside the equipment to normal levels. Precautions for chemical reactions in chemical processing processes 1. Precautions in oxidation reactions ★ When air or oxygen is used as an oxidizing agent in the oxidation process, the ratio of the reaction materials must be strictly controlled to stay outside the explosive range. ★Before air enters the reaction vessel, there must be a purification device to remove dust, moisture, oil, and other impurities from the air that could reduce the catalyst’s effectiveness or cause poisoning, thereby maintaining the catalyst’s activity and reducing the risk of fires and explosions. ★To prevent the contactors from posing a threat to the safety of personnel and equipment in the event of an explosion or fire, fire arresters should be installed in front of the reactor and within the pipelines. ★To prevent explosions in contactors, they should be equipped with pressure relief devices (explosion-proof membranes or discs), and automatic control systems for regulation as well as alarm and interlock devices should be used wherever possible. Precautions during the nitration reaction ★ Nitration is an exothermic reaction, so it must be carried out under cooled conditions. ★It must be noted that in the nitration reaction, even the slightest carelessness—such as stopping stirring midway, inadequate cooling water, or too fast feeding rate—can cause a sharp rise in temperature, leading to the formation of poly-nitro compounds and posing a risk of fire or explosion. ★Nitrating agents possess certain oxidizing properties. Common nitrating agents such as concentrated nitric acid, sulfuric acid, fuming sulfuric acid, and mixed acids all have strong oxidizing, hygroscopic, and corrosive properties. During use, it should be kept away from oils, organic substances, especially unsaturated organic compounds, as this may cause combustion. When preparing nitrating agents, the temperature must not be too high and no small amount of water should enter (to prevent equipment leaks), otherwise it can cause combustion and explosion. ★Most of the substances that are nitrated are flammable, such as derivatives of benzene, toluene, chlorobenzene, and naphthalene. Not only are these substances flammable, but some of them are also toxic; therefore, it is necessary to implement appropriate safety measures during their use to prevent fires, explosions, and poisoning incidents. Precautions for the chlorination reaction ★ Most of the raw materials used in this reaction process are organic flammable substances and strong oxidizers, such as methane, ethane, benzene, toluene, ethanol, liquid chlorine, etc. It is necessary to strictly control the safe distance from sources of fire during production, and to adhere strictly to the fire and explosion prevention requirements of the manufacturing facility. ★The chlorination agents commonly used in the chlorination process are liquid chlorine or gaseous chlorine. Chlorine gas is highly toxic (classified as Category II, highly hazardous); therefore, before use, liquid chlorine must first be fed into an evaporator to be vaporized. ★Under normal circumstances, cylinders or tank trucks used to store chlorine shall not be used as storage tanks, in order to prevent chlorinated organic substances from flowing back into them and causing an explosion; a chlorine buffer tank must be installed in between. ★When using chlorine, it is necessary to have complete personal protective equipment available, as well as a reliable emergency response plan; the safety measures outlined in this plan must be implemented. ★The chlorination reaction is an exothermic reaction; especially when carried out at higher temperatures, the reaction becomes more intense. Chlorination reaction equipment must be equipped with a good cooling system, and the flow rate of chlorine gas must be carefully controlled to prevent violent reactions and sudden temperature rises that could lead to accidents. ★Furthermore, chlorination reactions almost always produce hydrogen chloride gas; therefore, during use, special attention should be paid to the selection of corrosion-resistant materials for the equipment and to the recovery of hydrogen chloride gas. Precautions for fire and explosion prevention 1. Fire and explosion prevention measures ★In areas prone to fires and explosions, it is necessary to install adequate monitoring devices for excessive temperature and pressure, as well as alarm systems (sound and light) and safety interlock devices. ★In areas where flammable gases (vapors) may leak and spread, gas concentration detectors and alarms should be installed, with the alarm threshold set at less than 20% of the lower limit for the explosion of that gas. ★All pipelines for transporting inert gases or oxidizing gases that are connected to flammable and explosive devices shall be equipped with mechanisms to prevent the entry of such flammable and explosive substances, but check valves alone should not be used. ★For equipment where reactions of the materials lead to runaway polymerization, decomposition, etc., resulting in excessive temperature and pressure, facilities such as automatic and manual emergency pressure relief and discharge tanks should be installed. ★A flame arrester should be installed at the outlet of the vent pipe for combustible gases (vapors), and a stop valve should be placed in a location that is easy to access. To cut off the gas supply and extinguish the fire in case of a fire at the outlet of the vent pipe. A fire extinguishing pipe fitting should be installed at the lowest point of the vent pipe. 2 Principles and practices of fire and explosion prevention. For a fire to occur, three conditions are necessary: fuel, an oxidizing agent, and a heat source. A. Control combustibles: Prevent flammable gases, vapors, dust, and air from forming explosive mixtures ； B. Eliminate the source of ignition ； C. Isolate from air: Remove oxidizing agents such as oxygen. Precautions for handling chemical hazards ★Before loading, unloading, or transporting chemical hazards, it is necessary to carry out preliminary preparations: understand the properties of the substances, and check whether the tools used for handling are in good condition; those that are not in good condition should be replaced or repaired. If the tool has been contaminated by flammable substances, organic materials, acids, alkalis, etc., it must be cleaned before use. ★Operators should wear appropriate protective equipment according to the hazardous characteristics of different materials; extra caution is required when working with toxic, corrosive, radioactive, and similar substances. Protective equipment includes work clothes, rubber aprons, rubber sleeve covers, rubber gloves, rubber boots, gas masks, filter respirators, gauze masks, gauze gloves, goggles, etc. Before starting the operation, a designated person should check whether the tools are in good condition and whether the appropriate protective gear is being worn. After use, it should be cleaned or disinfected and stored in a dedicated cabinet. ★When handling chemical hazards, they must be handled with care to avoid impact, friction, dropping, and vibration. When unstacking liquid iron barrels in containers, do not use a ramp to slide them down quickly; instead, place old tires or other soft materials on the ground beside the stack and lower the barrels slowly. Items marked with a warning against inversion must never be turned upside down. If a breach in the packaging is detected, it must be moved to a safe location for repair or the packaging must be replaced; tools that may generate sparks should not be used during the repair process. When chemical hazardous materials spill on the ground or vehicles, they should be swept up promptly. For flammable and explosive substances, soft materials soaked in water should be used for cleaning them up. ★When handling toxic substances, it is necessary to ensure good air circulation at the work site. If symptoms of poisoning such as nausea or dizziness occur, one should immediately go to a place with fresh air to rest, remove their work clothes and protective gear, and clean any contaminated areas of the skin. ★When handling explosive materials, Class 1 flammable materials, and Class 1 oxidizing agents, it is not allowed to use iron-wheel carts, battery-powered vehicles (battery-powered vehicles without devices to control sparks), or other transportation tools that lack explosion-proof features. Those participating in the assignment must not wear shoes with metal studs. ★When handling highly corrosive substances, check whether the bottom of the container has been corroded prior to operation, to prevent any accidents caused by the container breaking open. It is prohibited to carry it on shoulders, back, or by holding it with both hands; it must be lifted, carried, or transported using a vehicle. During handling and stacking, do not invert, tilt, or shake it to prevent liquid from spilling out and causing danger. Clean water, soda water, or balanced acetic acid should be available on site for use in emergency situations. Precautions for working inside tanks in chemical plants ★ When entering equipment to carry out work, do not enter until the flow of materials has been stopped ； Items that fail the cleaning and replacement test are not allowed to proceed ； Lanterns that do not meet the specifications will not be allowed in ； No entry without a guardian ； Do not enter without backup measures for accident rescue. ★Sampling and analysis are conducted 30 minutes before starting the tank entry operation; work can proceed only if the concentrations of flammable, explosive, toxic, and harmful substances as well as the oxygen level are within acceptable limits. Enhance ventilation inside the tank depending on specific conditions ； In poorly ventilated areas, intermittent operation should be adopted. ★When entering the tank to remove toxic, harmful, and corrosive residues, it is necessary to wear appropriate personal protective equipment and gas masks. ★After starting operations on the equipment, gas composition should be sampled and analyzed every 2 hours ； The personnel monitoring outside the tank should remain at their posts and maintain close communication both internally and externally. ★When the concentration of toxic gases is below the **specified value, it is strictly prohibited to fill the tank with oxygen. Electrical safety precautions ★ Electrical equipment must have a reliable grounding (earthing) system. Lightning and static protection facilities must be in good condition, and regular inspections should be carried out annually. ★Electrical work must be carried out by personnel who have received professional training, passed relevant assessments, and hold the necessary certificates. They must wear appropriate personal protective equipment as required and use electrical tools that meet safety standards. ★Whether the high-voltage equipment is energized or not, the duty personnel must not remove the shielding cover or work around it alone. If it is necessary to remove the barrier, a supervisor must be present, and the safety distance required to keep the equipment powered on must be maintained. ★During thunderstorm weather, when it is necessary to inspect outdoor high-voltage equipment, the inspectors must wear insulating boots and must not approach lightning protection devices. ★Before installing grounding wires on de-energized lines and equipment, it is necessary to discharge and test for electricity; once it is confirmed that there is no electricity present, grounding wires should be installed on both sides of the work area. Ground wires should also be installed on any branch lines that may supply power to the equipment and lines that are under power outage. ★When working with fire near live equipment, the distance between the flame and the live parts should be 1.5 meters for voltages of 10 kV or less, and 3 meters for voltages above 10 kV. ★When replacing a fuse, it is necessary to select the fuse wire strictly in accordance with the regulations; other metal wires must not be used as substitutes. Precautions for using gas masks ★ Before using a gas mask, it is necessary to analyze and test the concentration of toxic gases and the oxygen level in the working environment. ★In the environment where gas masks are used, the oxygen concentration should be above 18% and the gas concentration should be below 2%. If either of these conditions is not met, the use of filter-type gas masks is strictly prohibited. ★Pay attention to the range of use and effective protection time for various types of gas filter canisters. ★If you feel unwell during use and cannot remove the gas mask, immediately evacuate the contaminated area. ★It is strictly prohibited to use filtering gas masks in enclosed containers, pipelines, and oxygen-deficient environments.