When constructing and repairing gas pipelines for welding, sometimes magnetic bias blowing will affect the welding process. Gb6479 seamless steel pipe is mainly used to produce products of pneumatic or hydraulic components, such as air cylinder or oil cylinder. The chemical composition of precision seamless steel pipe includes carbon C, silicon Si, manganese Mn, sulfur s, phosphorus P and chromium CR. The formation of magnetic bias blowing is the result of residual magnetism in the tube metal.
Generally, remanence is divided into induction magnetism and technology magnetism. Induction magnetism is often produced in the links of factory pipe making, such as metal smelting, loading and unloading with electromagnetic crane, steel pipe stopping in strong magnetic field, completing nondestructive inspection with magnetization method, steel pipe placing close to strong power supply line, etc.
Process magnetism is often produced during assembly welding and the use of magnetic grippers, clamps and DC welding pipes, such as long-term contact with the conductive wire connected to the DC power supply, the exposed section of the conductor or the short circuit between the welding clamp and the pipe.
When welding magnetic steel pipe, we often see the difficulty of arc ignition, the destruction of the stability of arc combustion, the deviation of arc in the magnetic field (definition: the field transmitting the magnetic action between objects), and the splashing of liquid metal and slag melt from the welding pool.
In order to stabilize the welding process and improve the quality of welded joints, the magnetized steel pipe shall be demagnetized before welding. Gb9948 seamless steel pipe is divided into high-pressure seamless steel pipe for chemical fertilizer equipment according to its purpose; Seamless steel pipe for geological brick exploration; Seamless steel pipe for petroleum brick exploration; Seamless steel pipe for petroleum cracking; Seamless steel pipe for ships; Cold drawn cold rolled precision seamless steel pipe; Various alloy pipes. It should be pointed out that it is difficult for the welded steel pipe to achieve complete demagnetization. Therefore, when the residual magnetism is insufficient to affect the welding quality, welding is allowed.
Post time: Feb-15-2022