Development of ERW steel pipe

Date:2024-05-20Tags:ERW steel pipe,casing and tubing

ERW steel pipe (High-frequency electrical Resistance Welded Steel Pipe ) is a hot-rolled coil formed by the forming machine. The skin effect and proximity effect of high-frequency current are used to heat and melt the bad edge of the pipe. The steel pipe is produced by pressure welding under the action of the extrusion roll. At present, in the production of welded steel pipes in the world, ERW welded pipe production accounts for about 80% of the total output of welded pipes.

ERW steel pipes

Since Fritz-Moon developed the continuous welding method in the 1820s, welded pipe forming, welding and inspection technology have developed rapidly. As one of the manufacturing technologies for small and medium diameter steel pipes, ERW steel pipe (Electric Resisted Welded) manufacturing technology has achieved rapid development and application. In the early days of ERW steel pipe production, due to the low market recognition of welded pipes and the constraints of raw materials, welded pipes were only used as pipes for general fluid transportation and simple engineering structures; the corresponding ERW steel pipe process was relatively simple, and the production line started from steel The coil starts and ends after the steel pipe is cut. The raw materials are mostly strip steel or steel coils cut into strips; the production mainly focuses on improving the unit's production capacity and production efficiency.


In the 1950s, the high-frequency resistance welding (ERE steel pipe) method was applied to the production of welded pipes. In the past ten years, its production technology has become more and more perfect and product quality has continued to improve. First, the quality of raw materials used in ERW production has been significantly improved. Low carbon, low phosphorus, low sulfur steel component design, micro-alloying; converter smelting, ladle refining, vacuum degassing, ERW steel pipe. The production pipeline steel, which represents the highest level of hot-rolled steel strips in China, has reached the requirements of the American Petroleum Institute API 5L standard and is at the leading international level.


Nowadays, China's domestic ERW steel pipe production technology has become mature and diversified, production capacity has reached a relatively saturated level, and export volume is growing rapidly. According to statistics from the Steel Pipe Branch of the China Steel Structure Association, the export volume of welded pipes with diameters less than 406.4mm (this part of welded pipes are mainly pipeline pipes, oil casing pipes, carbon pipes, and alloy steel ERW welded pipes) increased by 93.4% in 2006 compared with 2005; And its export price is one-half of the import price, showing the structural contradiction of ERW steel pipe varieties. This product structural contradiction must be alleviated with new technologies and different tube making processes. In developed countries and regions such as Japan and Europe, while improving and improving the forming and welding technology of ERW pipe making, the pipe making process is extending in the upstream and downstream directions; the pipe making process of ERW steel pipe units has a clear product positioning basis. On the other hand, we are developing in the direction of specialization of process technology, differentiation of product technology and energy saving and consumption reduction.


Secondly, in the process of forming and welding heat treatment of large and medium diameter ERW steel pipe, many companies have realized the automatic control of the computer, and through the automatic compensation system of the computer, the heat input energy in the high-frequency welding process is effectively controlled. Prevent low welding heat input energy resulting in cold welding, welding and overheating due to high heat input energy. The control of medium frequency heat treatment temperature enables the heat treatment process to achieve the best results according to the process requirements, thus effectively ensuring the quality of the weld and the heat affected zone.


In addition, advances in detection technology have enabled online or offline full welding ultrasonic or eddy current damage detection. Hydraulic testing can also be performed under computer supervision and stabilization upon request. The promotion and implementation of ISO9000 series standards and APIQ1 specifications have ensured the entire process of quality assurance in the production, inspection, sales and service of large and medium-sized ERW steel pipes. In recent years, countries are actively studying the use of ERW steel pipes to replace seamless steel pipes and spiral steel pipes. In industrially developed countries, where the diameter is less than 610mm, the proportion of ERW has reached about 70%.


The purpose of manufacturing products is to meet certain social functional needs, and the same is true for the production of ERW steel pipes. Nowadays, ERW steel pipes have been increasingly used in fields such as machinery, automobiles, energy, large engineering structures, and reprocessing. Take Japan's Nippon Steel Corporation's development and application in the field of welded pipes as an example. Its products involve various major fields of industrial production.


ERW welded pipes are mainly used in small and medium-diameter structural pipes, oil casings and tubing, pipeline pipes and boiler pipes, and this demand will tend to be classified and refined with changes in market demand and advancements in production technology. Small-diameter welded pipes are mainly used in institutional structures, automobiles, petroleum and petrochemicals, boilers and other fields, with the product's high performance, high precision, good surface finish and good processing performance as the main development directions; medium-diameter welded pipes are mainly used in petroleum and petrochemical, In the fields of marine and large engineering structures, the main development directions are products with high strength, high toughness, high corrosion resistance, good weldability and safety. This difference in demand will lead the process technology of small and medium-diameter ERW steel pipes to expand in different directions.

 

 

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