Compared with traditional pipe, seamless steel pipe has lighter material, high strength, good resistance, can withstand high internal pressure, is sensitive to production, and can be used in messy or harsh geological conditions. However, there are drawbacks in the use process, mainly because the internal and external anti-corrosion treatment is more troublesome. The first is the problem of anti-corrosion of the outer wall. The quality of the anti-corrosion of the outer wall directly affects the service life. At present, the outer wall anti-corrosion of domestic steel pipes is mainly concealed. The steel pipes are required to be reinforced or specially reinforced outer wall anti-corrosion, and some areas promote cathodic protection. Common external wall anti-corrosion methods include coatings such as petroleum asphalt and epoxy coal tar pitch. The latter is not easy to cure at low temperatures, and there are many problems in the construction of welding joints on the site. In the past, chlorosulfonated polyethylene was used because of the large amount of solvent. It is easy to produce pinholes and is not suitable for breakdown. Some areas are no longer used. The anti-corrosion effect of cathodic protection is better, but the method of sacrificing the anode is adopted, and the anode must be replaced regularly in the future operation, which increases the running cost and operation.

The welding process of the erw pipe is to use the skin-receiving principle generated by the high-frequency current to heat the edge of the hot-rolled coil to a molten state, and then perform welding by a mechanical extrusion method. The steel pipe produced by the process will have a white fusion line at the center of the weld, and the heat-affected zone on both sides of the fusion line will have a metal flow line extending from the middle to the inner and outer surfaces. Since the erw pipe is made of a base material as a welding material, the performance of the weld seam has a great relationship with the performance of the base material. In ordinary materials, the ductile-brittle transition temperature curve of the weld and the base metal. In ordinary materials, the difference in absorbed energy values between the weld and the base material in the Charpy impact test is small. On the contrary, there is a big difference in the high toughness material, and the weld impact toughness is obviously inferior to the base metal, but it is obviously superior to the weld of the ordinary material. It can be seen that the impact toughness of the weld center of the high-frequency steel pipe is generally lower than that of the base material. Even if the toughness material is used, although the toughness of the weld is improved, the impact toughness of the weld center cannot be completely improved.