Exploring the safe handling of chemical equipment during maintenance

Achieve chemical safety overhaul not only to ensure the safety of overhaul operations, to prevent major accidents, to protect the safety and health of workers: but also to promote overhaul operations on time, according to quality, according to the amount of completion, to ensure the quality of equipment overhaul operations, so that the equipment into operation after stable operation, high operating rate, to eliminate accidents and pollution of the environment, to create good conditions for safe production. To this end, it is important to do a good job in the safety and technical processing of parking before and after overhaul. 1, before the overhaul parking safety technology processing Parking program once determined, should be strictly in accordance with the parking program to determine the parking time, steps, process changes, as well as to confirm the parking operation sequence table, organized, orderly. The smoothness of the plant stopping phase will, on the one hand, affect the safety of production and, on the other hand, the safety of plant maintenance operations and the quality of safety maintenance. The main safety techniques for stopping the plant are as follows: 1.1 Stop the plant in strict accordance with the scheduled stopping programme. Stop the plant in strict accordance with the stopping programme by maintaining close contact with the upstream and downstream processes and relevant sections (e.g. boiler room, distribution room, etc.). 1.2 Pressure relief should be slow and moderate Pressure relief should be carried out slowly and the equipment should not be dismantled until the pressure has been relieved. 1.3 The material in the equipment must be emptied and disposed of. Before discharging residual materials, the discharge port must be inspected and no flammable, explosive, toxic or corrosive materials should be discharged arbitrarily into the sewer or onto the ground, but the residual materials in the equipment or piping should be discharged to a designated safe place or storage tank to avoid accidents or pollution. At the same time, the material in the equipment and piping should be emptied and pumped out as far as possible, and any flammable or toxic gases that cannot be collected and used should be discharged to a flare and burnt or otherwise disposed of. 1.4 Control the appropriate speed of temperature and volume reduction The speed of temperature and volume reduction should be carried out in accordance with the requirements of the process to prevent deformation and damage to high temperature equipment. If high temperature equipment is cooled down, it should not be cooled down directly with cold water immediately, but after the heat source is cut off, it is appropriate to use the appropriate amount of ventilation or natural cooling. The speed of cooling down should not be too fast, especially in high temperature conditions, the temperature and material volume of rapid changes will cause equipment and pipeline deformation, rupture, causing flammable and explosive, toxic media leakage or lead to fire and explosion or poisoning accidents. 1.5 The speed of opening the valve should not be too fast When opening the valve, open the first two buckles of the valve to stop for a moment, so that a small amount of material through, observe the smooth flow of materials, and then gradually open the valve until it reaches the requirements. When opening the steam valve, pay attention to the preheating of the pipeline, drainage and waterproofing etc. 1.6 High temperature vacuum equipment parking steps High temperature vacuum equipment parking, must first eliminate the vacuum state, until the temperature of the medium in the equipment to fall below the spontaneous combustion point, only then can be connected with the atmosphere, to prevent the air into the combustion, combustion and explosion accidents. 1.7 Stop furnace operation in strict accordance with the provisions of the process regulations Stop furnace operation should be carried out in strict accordance with the cooling curve specified in the process regulations, pay attention to the impact of the flame out of each part of the furnace cooling uniformity. When the nozzles are not completely extinguished or the furnace chamber temperature is high, evacuation and low-point condensation should not be carried out to avoid accidents caused by combustible gases entering the furnace chamber. At the same time, when the device is stopped, the operator has to open and close many valves and instruments within a short period of time. In order to avoid errors, close attention must be paid to the changes in temperature, pressure, flow rate, liquid level and other parameters in each part. 2, completely cut off the source of media within this equipment into the chemical equipment internal operations, must be shut down on this equipment, in the shutdown of the single equipment to ensure that all media can not occur internal leakage. As the equipment has been in use for a long time, many of the pipeline valves connected to this equipment are not in position to open and close and internal leakage will occur, especially in the case of gas valves. If the inspectors do not check the piping carefully after entering the equipment, if gas or liquid leakage occurs, especially in the case of flammable, explosive, high temperature and high pressure substances such as gas, ammonia, acid gas, high pressure gas and crude benzene, internal leakage will cause fire, explosion and burn. Will cause fire, explosion, burns, poisoning and other serious accidents, the consequences are unimaginable, so the process must be carefully confirmed and equipment connected to all the pipeline, for some flammable, explosive, easy to poison, high temperature, high pressure media pipeline to be in the valve after (near the tower end) plus blind. 3.Replacement of toxic and hazardous gases in the equipment Replace toxic, hazardous, flammable and explosive gases in the equipment. Generally used for the replacement of gases are nitrogen, steam, to give priority to the replacement of nitrogen. Because of the high temperature of steam, after the replacement is completed, the tower must be cooled so that the temperature in the equipment is reduced to room temperature. For some high-temperature liquid equipment, the first consideration should be to vent, and then use the cold material or add cold water to reduce the equipment to normal temperature. For equipment with pressure, use the method of pressure relief to bring the gas pressure inside the equipment down to normal pressure. 4, the correct disassembly of the manhole in the maintenance equipment for media isolation, replacement, cooling, pressure reduction and other processes, to carry out strict confirmation, testing, in order to ensure the safety of the situation before disassembly into the hole, for equipment with liquid, demolition into the hole, to remove the diagonal bolts, remove to the last four diagonal bolts, to slowly remove, and try to avoid the side of the manhole, to prevent liquid ejection injury. For equipment with flammable and explosive substances, it is absolutely forbidden to cut the bolts with gas welding. For severely corroded bolts, cut them with a hand saw. For crude benzene tanks and other devices with new manholes or open new manholes, it is absolutely forbidden to cut them with gas welding or grinding wheel blades, and new manholes and manholes should be opened by means of wax sealing around them using a certain ratio of sulfuric acid concentration. 5, the correct labour protection dress code labour protection is not simply put on the work clothes can be, in the chemical equipment into the internal work; labour protection must play a protective role, there are certain protective requirements. In flammable and explosive equipment, anti-static overalls should be worn, neatly dressed, with buttons fastened to prevent electrostatic sparks or corrosive substances from contacting the skin, and the pockets of the overalls should not carry sharp corners or metal tools, and some small tools, such as angle rulers, should be put into special tool bags. Safety cap must ensure that the cap belt buckle tight, hat and head with wear suitable, because in the equipment internal work construction space is not enough, is likely to appear touch head phenomenon, but also to ensure that the cap core and cap shell between leave a certain gap, prevent falling objects hit the cap after the cap core can not be the cap and the head apart, cap shell directly pressed in the head cause injury. Therefore, the inside of the cap core should be left with enough buffer distance. Correctly wear labour gloves, in some acid, alkali and other corrosive equipment within the work to wear acid, alkali and other anti-corrosion gloves, gloves are bad to replace in a timely manner, especially in the summer work hand sweating more, will reduce the insulation performance of gloves and slippery phenomenon, so it should be best to have a few pairs of gloves. Labour shoes should be anti-static and anti-smashing special shoes. The soles of the shoes should be stitched, not nailed, and the slip resistance should be taken into account, and the laces should be tightened to ensure easy walking. When working in the conditional tower, try to lay some asbestos sheet or rubber skin at the bottom of the tower in the operating range, which is non-slip and isolates the direct contact between the person and the equipment. Chemical equipment in the overhaul before the above safety technology processing can be for the smooth conduct of chemical equipment overhaul operations to provide a good operating environment, to ensure the safety of the overhaul operations and the normal operation of the equipment after the overhaul to provide a reliable guarantee. The characteristics of chemical production determine that chemical equipment overhaul operations are complex, technical and risky. Only by carrying out a series of safety technical treatments on chemical equipment before overhaul, and eliminating all possible hazards, can we ensure the smooth conduct of overhaul operations, guarantee the quality of overhaul and create good conditions for safe production.
Source: China Chemical Equipment Network