Welded steel pipes are mainly divided into three processes: electric resistance welding (ERW), spiral submerged arc welding (SSAW), and straight seam submerged arc welding (LSAW). The welded pipes produced by these three processes have their positioning and advantages in the application field due to their different raw materials, forming processes, caliber sizes, and qualities. However, in terms of its development, the new production capacity of large-diameter welded pipes above Ф273mm has been too concentrated in recent years. There are 8 sets of JCOE (UOE) and 6 sets of Ф508~610mm ERW units that have been put into production and are about to be put into production. The preliminary statistics of its production capacity have exceeded 6 million tons. For these devices, according to the requirements of the application field and the characteristics of their respective products, technological transformation should be carried out based on their respective strengths, and the technical content of their respective products should be continuously improved. 1. ERW welded pipe (ERW welded pipe) is the steel pipe variety that was first produced in my country, has the widest application range, the largest number of production units (more than 2,000), and the highest output (accounting for about 80% of the total production capacity of welded pipes). , the product specification is Ф20～610mm, which has played an important role in the national economic construction.
A． ERW steel pipe 20-89ram has the largest number of units (accounting for more than 90% of the total ERW), and its production capacity accounts for more than 60% of the total ERW production capacity. Due to the low unit investment, low technological level, and low cost, it is widely used in low-pressure fluid delivery pipes, construction scaffold pipes, bicycles, and furniture structure pipes. These products are the most competitive in the market, and some enterprises with simple equipment, backward technology, small scale, and poor quality will be eliminated from the competition. Only by adopting advanced technology to transform the unit, improving the level of technical equipment, improving product quality, and increasing added value and technical content, can we remain invincible in the fierce market competition.
B． ERW steel pipe 219-610mm unit since the 1980s, there are more than 30 sets of relatively advanced technology imported from abroad. After years of production practice, the technical level of equipment has been greatly improved, and the product quality has also been continuously improved. Because of its low investment, quick results, and wide range of applications, it has developed rapidly. With the development of sheet CSP production technology, it provides low-cost, reliable raw materials, and creates good conditions for its further development in the future. This part of the products has been developed from the field of fluid transportation and structure to oil well pipe and line pipe in the field of seamless pipe application.
Its typical production process should be strip raw material → raw material pretreatment → cold bending forming → welding → weld seam heat treatment → weld seam (pipe body) flaw detection → finishing → finished welded pipe. Great efforts must be made to thoroughly solve the key technologies of ERW such as the elimination of gray spot defects, so that the product quality of the newly put into production large-diameter: ERW units can reach the international advanced level as soon as possible, and avoid repeating my country's ERW development process due to major quality accidents. The failure of the trough has made my country's ERW on the track of healthy development.