Before liberation, there were only a few welded pipe units in my country. By 1958, China's pipe welding machines were generally imported from the Soviet Union, and Tianjin No. 1 Steel Rolling Plant imported a Φ60 unit at that time. Following that, Shougang Plant imported Φ102 units, and Baoji Steel Pipe Plant imported Φ650 spiral welding units.
In 1960, the immature intermediate frequency welding technology was replaced by high frequency welding technology. Since then, it has entered the era of high frequency welding, and the basic principle of high frequency welding has been used until today. High-frequency welding technology first developed rapidly in the United States, forming two processes of high-frequency contact welding (called high-frequency resistance welding at the time) and high-frequency induction welding. At the same time, the steel strip production technology has also made breakthrough progress, laying the foundation for the development of the welded pipe industry, and driving the welded pipe manufacturing industry into a glorious era of high-frequency welding.
In terms of technology, after more than 10 years of development, in the early 1970s. Breakthrough progress has been made in the production technology of high-frequency welded pipes. The first is the forming technology, which expands the range of thick tube wall and thin tube wall, forming a roll forming technology for small and medium diameter welded pipes.
In the early days of the birth of high-frequency welded pipes, the quality of welded pipes was identified by the human eye. By the 1960s, various production lines of non-destructive inspection devices for welds appeared. Such as: rotating ultrasonic flaw detection, vortex flaw detection, electromagnetic flaw detection, etc... This not only saves a lot of labor, but also better ensures the reliability of quality. At the same time, the internal burr technology has also been improved. After the burr is removed, the inner surface can also pass the non-destructive testing of the steel pipe, which improves the aesthetics and commercial value of the steel pipe.
In terms of material storage, the vertical looper technology developed in the United States in the early stage has perfected the development process and made great contributions to the world. Later, similar loopers were developed in the United States and Europe, making spiral loopers the standard configuration for small and medium-sized high-frequency welded pipe units. Nowadays, according to the width of the steel belt, it is generally divided into vertical storage racks and horizontal spiral loopers.
In terms of market, high-frequency welded pipes are widely used in civil construction, petrochemical, light industry and other sectors
