Welding thermal cycle refers to the process that the temperature of a certain point on the edge of the tube changes over time under the action of the heat source generated by the high-frequency welding current.

The welding process of seamless steel pipe includes: heating before welding, heat treatment after welding, quenching.

In addition to the skin effect, the proximity effect is another characteristic of current. When alternating currents of equal magnitude and opposite directions pass through two adjacent conductors, the current will flow through the adjacent inner surface layers of the two conductors, and when the two conductors pass When alternating currents of the same size and direction, the current will flow through the outer surface layers of the two conductors.

High-quality pipes are different, because such pipes have undergone some anti-oxidation treatments. This makes the surface of the pipe, with a protective film, looks very shiny.

In the production process, the pickling process is to remove the surface oxide scale, and then go through lubrication treatment (carbon steel-phosphorous saponification, stainless steel-butter lime, copper aluminum pipe-oiling), using the old process-copper plating), and then For drawing and deep processing.

The selection principle of the non-destructive testing method for the surface of the straight seam steel pipe: the ferromagnetic steel pipe is selected for magnetic particle testing, and the non-ferromagnetic steel pipe is used for the penetration test.