The technological development process of ERW steel pipe

High-frequency welded steel pipe (ERW) is the use of the skin effect and proximity effect of high-frequency current after the hot-rolled coil is formed by a forming machine.The edge of the tube blank is heated and melted, and pressure welding is carried out under the action of the extrusion roller to achieve production.

The high-frequency resistance welding method has been used in the production of welded pipes since the 1950s. In the past ten years, its production technology has become more and more perfect, and its product quality has been continuously improved. First of all, the quality of the raw materials used in ERW production has been significantly improved. Low C, low P, S, micro-alloying in the design of steel components; converter smelting, ladle refining, vacuum degassing, continuous casting and other new technologies in the smelting process The use of controlled rolling and controlled cooling technology in the rolling process has greatly improved the appearance size, appearance quality, and physical and chemical properties of hot-rolled steel strips for large and medium-diameter ERW steel pipes.

Secondly, computer automatic control is realized in the production process of large and medium-diameter ERW steel pipe forming, welding, heat treatment and other processes. During high-frequency welding, the heat input energy is effectively controlled with the automatic compensation system of the computer, which prevents the welding heat input energy from being low. Caused by cold welding, virtual welding and over-burning caused by high heat input energy. The control of the intermediate frequency heat treatment temperature enables the heat treatment process to achieve the best effect according to the process requirements, effectively ensuring the quality of the weld and heat affected zone.

In addition, with the advancement of detection technology, online or offline full-weld ultrasonic or eddy current exploration can be realized, and the water pressure test can also be tested and stabilized as required under the monitoring of the computer. The promotion and implementation of ISO9000 series standards and APIQ1 specifications make the production, inspection, sales and service of large and medium diameter ERW steel pipes in a whole process of quality assurance. In recent years, all countries are actively studying the use of high-frequency welded (ERW) steel pipes to replace seamless pipes and spiral welded pipes. In industrially developed countries, the diameter of high-frequency welded pipes is below Ф610mm, and the proportion of ERW has reached about 70%.