Safety technology in steel mills

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Safety Technology in Steel Rolling Mills 1. Main characteristics of safe steel rolling production Steel rolling is the process of rolling the ingots or continuous cast billets produced in steel mills into finished steel products. The steel products manufactured by this rolling method can be roughly classified into sections, wires, sheets and strips, steel pipes, and special steel types, depending on their cross-sectional shape. Steel rolling methods can be divided into hot rolling and cold rolling based on the rolling temperature ； Based on the relative motion between the workpiece and the rolls during rolling, it can be divided into longitudinal rolling and transverse rolling ； Based on the forming characteristics of the rolled products, it can be divided into general rolling and special rolling. Spin rolling and bending forming both belong to special rolling. Rolling, like other processing methods, involves inducing plastic deformation in metal to create a specific shape. The difference is that steel rolling takes place between rotating rolls. Rolling mills are divided into two main categories: the main equipment of the rolling mill, or the main rolling units, and the auxiliary equipment. Equipment used to deform metal in rotating rolls is generally referred to as the main equipment. The line formed by the main equipment is called the main train of the rolling mill. The main machine train consists of three parts: the main motor, the rolling mill, and the transmission machinery. Rolling mills can be classified by purpose into: primary rolling mills and bloom mills, section rolling mills (large, medium, small, and wire), strip rolling mills, pipe rolling mills, and rolling mills for other special purposes. The bloomers and section mills in rolling mills are specified by the diameter of their rolls, while strip mills are specified by the length of their roll bodies. Pipe mills are specified by the maximum outer diameter of the pipes that can be rolled. 2. Key safety technologies in steel rolling: 1) Safety technologies for raw material preparation – It is necessary to have sufficient storage areas for raw materials, intermediate products, finished goods, as well as outdoor storage sites, to ensure the safe storage of metal materials. Billets are usually unloaded from the vehicle using disk cranes and single-hook cranes. When using a disk lift, the person operating it must check whether the disk is secure to prevent it from falling and hurting someone. Before using a single hook to unload, check the placement of the steel billets on the vehicle. Check whether the steel cables and safety pillars on the vehicle are complete, secure, and functioning properly. When unloading, the steel ropes should be placed in the middle, with a span of more than 1 meter between the two ropes, so that both ends remain balanced once the steel billet is lifted, before it is stacked. Hot steel billets above 400°C should not be lifted using wire ropes, to prevent the ropes from breaking and causing the billets to fall and result in injuries from impact or burns. The billets should be stacked steadily and neatly, with a certain distance between stacks to allow workers to move around easily and to prevent collisions when lifting the billets. The height of the stacks should be such that it does not interfere with the normal operation of the crane; near the billet handling line, the height of the stacks must not obstruct the driver’s view. Staff are not allowed to rest or stay between the billet stacks. Those lifting the load must carefully observe whether the steel billets on the stack are in balance when moving them up or down, to prevent them from rolling due to vibrations during the crane’s movement, or from toppling over while climbing, which could lead to crushing or crushing injuries. The surface defects of large steel billets are removed using flame, and its advantage is fast cleaning speed. Flame cleaning is primarily carried out through the combustion of gas and oxygen. Before starting work, it is necessary to carefully check for any leaks in the flame gun, gas and oxygen hoses, valves, connectors, etc., as well as to ensure that the air valves and gas valves function properly. Any temporary faults that arise during the process must be resolved immediately. If backfire occurs in the flame gun, immediately pull back the gas hose and quickly close the air valve to prevent injuries from a backfire explosion. The operation procedure for the flame gun follows the standard operating guidelines. The stacking and management of raw materials for medium and thick plates are very important. When stacking, the piles should be level and stable, with a height not exceeding 4.5 meters. Attention must also be paid to the proper operation and safe use of flame cutters. Preparation of cold-rolling raw materials: The steel coils used as raw materials for cold rolling all weigh over 2 tons, so lifting them safely is a key concern; the lifting equipment must be inspected regularly, and any signs of wear should be addressed by replacing it promptly. 2) Safety technologies for heating and heating furnaces: Safety of fuels and combustion. Fuels for industrial furnaces are divided into solid, liquid, and gas types. Different types of fuel and combustion have different safety requirements. Gaseous fuels are convenient to transport, easy to ignite, and allow for complete combustion. However, some gaseous fuels are toxic and pose an explosion risk; therefore, strict safety procedures must be followed when using them. When using liquid fuel, care should be taken to ensure that the preheating temperature of the fuel is not too high, and the amount of heavy oil entering the nozzle at the time of ignition should not exceed the amount of air. To prevent the rupture or explosion of oil pipes, it is necessary to regularly inspect the corrosion of oil tanks and pipelines. Open flames and smoking are prohibited in the vicinity of oil storage tanks and oil pipeline systems, and fire extinguishing equipment must be available. Accidents in industrial furnaces are mostly caused by inadequate maintenance, inspection, and operational errors. First, it is necessary to check whether all systems are in good condition, strengthen maintenance efforts, identify potential problem areas promptly, and take immediate action to address them in order to prevent accidents. Safety precautions for soaking furnaces, heating furnaces, and heat treatment furnaces: All types of transmission mechanisms should be equipped with safety power supplies. The pipelines, valves, and various measuring instruments related to hydrogen, nitrogen, gas, air, and drainage systems, as well as all kinds of sampling and analysis equipment, and fire prevention, explosion prevention, and poison prevention devices, must be ensured to be complete and in good condition. 3) Safety technologies in cold rolling production. The characteristics of cold rolling production include low processing temperatures, a product surface free from defects such as iron oxide scale, high surface finish, and fast rolling speeds. Pickling is primarily done to remove surface iron oxide scale. During production, it is important to: ① Keep the protective devices in good condition to prevent mechanical injuries ； ②Pay attention to the dressing requirements to prevent acid splashes from causing burns. The cold rolling speed is high; be careful with your position when cleaning the rollers. The rollers must be stopped for grinding, and operations must also be halted in case of an accident – the main power supply should be cut off and the control handle returned to its zero position. When using X-ray thickness measurement, a reliable radiation protection device is necessary. Heat treatment is the key process for ensuring the performance of cold-rolled steel sheets, and the potential hazards include fires, poisoning, furnace collapse, and coil drop. Its protective measures include: ① When working in gas areas, it is necessary to strictly follow the \"Gas Safety Operating Procedures\" and ensure that the ventilation equipment is in good condition ； ②Replace the lifting gear promptly when it shows signs of wear, to prevent injuries from it.