Normalizing is to heat the steel pipe (such as seamless pipe and welded steel tube) to 30~50 degrees above Ac3 or Accm, and cool it at a cooling rate slightly higher than annealing after heat preservation. Annealing is to heat the steel pipe to a temperature of Ac3+30~50 degrees or Ac1+30~50 degrees or below Ac1, and generally cool slowly with the furnace temperature.

The quenching of steel pipes (such as seamless pipes, welded steel pipes) is to heat the steel pipe to the phase transition temperature Ac3 or above Ac1, keep it warm for a period of time, and then rapidly cool it in water, nitrate, oil, or air. The purpose is to obtain a martensitic structure with high hardness.

Laser cutting is the use of focused high-power-density laser beams to irradiate pipes, so that the irradiated materials are rapidly melted, vaporized, ablated or reach the ignition point. At the same time, the molten material is blown away by the high-speed airflow coaxial with the beam, so as to realize the cutting of the steel pipe. Laser cutting is one of the thermal cutting methods

Spiral welded steel pipe (SSAW pipe) will naturally become magnetic due to long-term friction during the production process. If the magnetism is too large, it will cause natural defects such as pores and slag inclusions in the spiral steel pipe, especially the detection rate of linear natural defects such as incomplete penetration and cracks.

The strip steel is sent to the welded pipe unit, rolled by multiple rollers, and the strip steel is gradually rolled up to form a round tube blank with an opening gap. Adjust the reduction of the extrusion roller to control the gap between the welds at 1~3mm, and make both ends of the welds flush.

Small-diameter welded steel pipe is a steel pipe made of steel plate or strip steel after crimping and welding. Small-diameter welded pipe has simple production process, high production efficiency, many varieties and specifications, and less equipment investment, but its general strength is lower than that of seamless pipe.