Safety technology of the hottest welding engineeri

Safety technology of welding engineering

in modern welding technology, the welding method of using electric energy to convert into heat energy to heat the metal has been the most popular compared with the frequently used titanium alloy. There are many forms of heat sources for electric energy heating, such as arc heat, plasma arc heat, resistance heat, and the heat released from the surface of the workpiece by electronic impact. Manual arc welding is a welding process that uses the heat generated by arc discharge to melt the welding materials and the welded workpiece, so as to obtain a solid joint

(I) welding properties of arc

arc is a lasting and powerful discharge phenomenon between two electrodes. The discharge produces high heat (the temperature can reach about 6000 ℃) and strong arc light at the same time. The heat produced by electric arc can be used for welding, cutting and steelmaking; The strong arc light generated by the arc can be used for lighting (such as searchlight) or film projection with the arc light

in order to keep the arc burning continuously and stably between the welding rod and the weldment, the no-load voltage of the electric welding machine is very high and the working voltage is low. According to the different welding power supply, it can be divided into AC welding machine and DC welding machine. Welding equipment includes welding power supply, control box, regulating mechanism, etc

(II) unsafe factors of electric welding operation

1. There are many opportunities for electric shock

(1) welders have the most opportunities to contact electricity, and they often have to work on line, such as contacting weldments, welding guns, welding tongs, grinding machines, worktables, etc. There are also regular live work such as adjusting current and changing welding rods. Sometimes you have to stand on the weldment to operate. It can be said that electricity is on the welder's hands, feet and around

(2) electric shock accidents may occur if the electrical device is faulty, the insulation of the primary power supply is damaged, the protective articles are defective or the operating procedures are violated

(3) the risk of electric shock is greater when operating in containers, pipelines, cabins, boilers or in the good atmosphere of "everyone has something to do"

2. electrical fire, explosion and scalding accidents are easy to happen

electrical fire, explosion and scalding accidents will happen during electric welding operation. Short circuit or overload work can cause electrical fire; When there are inflammables and explosives around, fire and explosion, such as the explosion of compressed steel cylinders, will be caused by sparks and sparks. Especially for the welding repair of fuel containers (such as oil tanks, gas tanks, etc.) and pipelines, strict explosion-proof measures must be formulated before welding, otherwise serious fire and explosion accidents will occur. Fire, explosion and sparks splashing during operation will cause scalding casualties

3. electric welding high-altitude operation

there are many electric welding high-altitude operations. In addition to the risk of falling directly from high places, there may also be secondary accidents of falling from high places due to out of control electric shock

4. mechanical injury

mechanical injury, such as crushing, crushing and other accidents may occur when welding heavy components

(III) safe operation

in order to prevent the occurrence of electric shock accidents, in addition to wearing protective work clothes, protective gloves and insulating shoes as required, it is also necessary to keep dry and symptoms: the electrical control switch fails to work and is clean. The operation process should comply with the following requirements:

(1) each electric welding machine should be equipped with a separate switch box, which is equipped with leakage switches on the power side and the handle side (secondary side). When there is leakage during the welding process or when the electric welding machine is unloaded, electric shock can be prevented

(2) before welding, check whether the welding machine and tools are intact, safe and reliable, such as whether the insulation of welding tongs and welding cables is damaged, and whether the shell of the welding machine is grounded and the connection points of the welding machine are in good contact. It is not allowed to start operation without safety inspection

(3) when working in a narrow space, cabin, container and pipeline, in order to prevent electric shock, insulating shoes must be worn, and rubber plates or other insulating pads must be padded under the feet; It is best for two people to work in rotation so as to take care of each other. Otherwise, a supervisor is required to pay attention to the safety of the operator at any time. In case of danger, the power supply can be cut off immediately for rescue

(4) when the clothes are wet after sweating, do not lean against the charged steel plate or workpiece to prevent electric shock

(5) when the working place is wet, the ground should be paved with rubber sheets or other insulating materials

(6) when replacing welding rods, you must wear leather gloves and do not operate with bare hands

(7) in case of electrification, for safety, the welding tongs shall not be clamped under the armpit to carry the weldment or hang the welding cable on the neck

(8) when pushing and pulling the switch at the beginning, the face is not allowed to face the switch directly to prevent sparks caused by short circuit from burning the face

(9) the following operations can be carried out only after the power supply is cut off: when changing the welding machine connector; When it is necessary to change the standard test modes such as 45 ° (± 22.5 °), 90 ° (± 45 °), 180 ° (± 90 °), 180 ° (± 90 °), 540 ° and the user-defined test mode to connect the secondary circuit; When replacing the safety device; When the welding machine needs to be repaired due to failure; When moving the welding machine when transferring the work place; When the work is completed or temporarily leaves the work site

(IV) gas welding and gas cutting

(1) gas welding is a fusion welding method that converts chemical energy into heat energy. It uses the flame of mixed combustion of combustible gas and oxygen to heat metal. The combustible gas used in gas welding is mainly acetylene gas (C2H2). The equipment used in gas welding mainly includes oxygen cylinders and acetylene generators (or acetylene cylinders); The instruments used include welding torque, pressure reducer and rubber hose. During gas welding, the filler wire of the weld can be selected according to the metal material to be welded, such as carbon steel welding wire, cast iron welding wire, brass welding wire, bronze welding wire, aluminum welding wire, etc. Gas welding is mainly used for the welding of steel sheets, non-ferrous metals, iron castings, cutting tools, push welding of cemented carbide and other materials, and the welding repair of worn and discarded parts

(2) gas cutting is a processing method that uses the preheating flame of mixed combustion of combustible gas and oxygen to heat the metal to the melting point, and violently melt it in the oxygen jet to separate the metal. The mixing of combustible gas and oxygen and the injection of cutting oxygen flow are completed by cutting torch. The combustible gases used for cutting are mainly acetylene and propane

(3) gas welding, gas cutting and safety. Fire and explosion are the main dangers of gas welding and gas cutting. The energy used for gas welding and gas cutting is acetylene, liquefied petroleum gas, oxygen, etc., which are flammable and explosive gases; Oxygen cylinders, acetylene generators, acetylene cylinders and liquefied petroleum gas cylinders belong to pressure vessels. When welding and repairing fuel containers and pipelines, many other flammable and explosive gases and various pressure vessels will be encountered. During gas welding and gas cutting operations, it is necessary to contact with dangerous goods and pressure vessels, and use open fire at the same time. If there is a problem with the welding equipment or safety device, or if it violates the safety operation regulations, it is easy to cause fire and explosion accidents. It can be seen that fire prevention and explosion prevention are the focus of gas welding and gas cutting safety

under the action of gas welding flame, especially the spray of oxygen jet during gas cutting, iron beads and slag splash everywhere, which is easy to cause burns. Moreover, large molten beads, sparks, slag, etc. can splash to a place 5m away from the operation point, which may ignite combustibles and explosives around the work place and cause fire and explosion

(V) gas cylinders

oxygen cylinders used for gas welding and gas cutting belong to compressed cylinders, acetylene cylinders belong to dissolved cylinders, and LPG cylinders belong to liquefied cylinders. When using, corresponding safety measures should be taken according to the different characteristics of various cylinders