With the development of production, the application of welding technology is becoming more and more widespread, along with the emergence of a variety of unsafe and unhygienic factors seriously threatening the safety and health of welders and other production personnel. The main hazards are as follows.

  1, welding and cutting work process requires contact with flammable and explosive gases, pressure vessels and electrical appliances; 2, the welding process will produce toxic gases, harmful dust, arc radiation, noise and radiation.

The above-mentioned hazards may, under certain conditions, cause occupational diseases such as explosions, fires, burns, poisoning, electro-optical ophthalmia and skin diseases. In addition, they may endanger the safety of equipment, plant and surrounding personnel, causing undue damage to the country and the enterprise. Many major and mega accidents are caused by welding and cutting operators operating outside the rules.

  This article discusses the characteristics, hazards and safe operation of gas welding and electrode arc welding, which are widely used on a daily basis.

     Gas welding

          1、Characteristics and hazards

            Gas welding has simple equipment, easy to operate, flexible, practical and other characteristics. Therefore, it is widely used in the manufacture and maintenance of various industrial sectors. However, this process requires the use of combustible gases (e.g. C2H2, LPG and H2 etc.), flux gases (O2) and high pressure cylinders (e.g. oxygen cylinders, acetylene cylinders etc.). If the welding equipment and safety devices are faulty, or if the operator violates the safety procedures, this may cause accidents such as explosions and fires.

            2. Safety requirements for use

            1), industrial acetylene often contains phosphine (PH3), hydrogen sulphide (H2S) and other impurities, these impurities are not only easy to cause explosions, and welding, which may transfer the sulphur and phosphorus to the weld metal, so that the mechanical properties of the weld change, cold brittle, hot cracking tendency to increase, the quality of the weld is difficult to ensure. Therefore, according to the volume calculation, the content of PH3 in acetylene should not exceed 0.2%; the content of H2S should be less than 0.1%.

            2) In the process of storage and use of gas cylinders, avoid sunlight exposure and keep away from open fire and heat radiation. 3) During the welding process, the bleeding speed should not be too fast to avoid electrostatic sparks when the gas flows through the valve.

            4) Acetylene cylinders should be placed vertically, not lying down. 5) Gas cylinders should be subject to regular technical inspection according to the requirements of the National Regulations for the Safety Supervision of Gas Cylinders, and the use of overdue cylinders is strictly prohibited.

            6) Operators should receive safety technical training and be licensed to work.

            7) The torch must be inspected before use, including the shooting suction, rubber tube and joint connection, whether the gas leakage, the cleanliness of the gas pathways, etc., check the normal before ignition operation. In the process of use, prevent the occurrence of backfire, once the backfire should quickly close the acetylene regulating valve, while closing the oxygen regulating valve.