Straight seam welded pipe (ERW straight seam welded steel pipe) is formed on the hot rolled plate of the forming machine, the skin effect and proximity effect of the high frequency current, melting of the pipe edge heating to the extrusion roller pressure welding to achieve production.
The application of high-frequency resistance welding method in pipeline production in the 1950s has witnessed more and more mature production technology and continuous improvement of product quality in the past decade or so.
First of all, in the quality of raw materials, the production of ERW steel pipe has been significantly improved, the composition of the steel design of low carbon, low P, S, micro-alloying; smelting process smelting, ladle refining, vacuum degassing, continuous casting and other new technologies In addition to the ERW controlled rolling and cold rolling process, the technology has enabled the appearance size of the hot rolled steel strips of large and medium caliber ERW steel tubes to be greatly improved in appearance quality, physical properties and chemical properties. The steel pipelines produced by Baoshan Iron and Steel Company, the highest level of hot rolled strip steel in my country, have met the American Petroleum Institute API 5L standard and are at the international advanced level.
Followed by the middle and large diameter ERW molding welding and heat treatment process of the production process to achieve the computer automatic control, high frequency and computer automatic compensation system welding process heat input energy is effectively controlled to prevent welding heat input welding cold caused by low welding heat input and Excessive combustion caused by high energy. The heat treatment temperature control allows the heat treatment process to achieve the best results according to the process requirements, effectively ensuring the quality of the steel pipe welding and heat-affected zone.
In addition, the progress of ERW tube straight seam welded pipe inspection technology has achieved full online or offline ultrasonic or eddy current weld risk damage, and the hydraulic pressure test may be under the supervision of a computer, stress testing and regulatory requirements. The promotion and implementation of the standard and specification APIQ1 ISO9000 series ensure the quality assurance in the whole process of production, inspection, sales and service of medium and large caliber ERW straight seam steel pipes.
In recent years, various countries have been actively adopting ERW straight seam welded pipe and spiral welded pipe seamless pipe in place, in industrialized countries, ERW straight seam pipe diameter Ф610mm less, ERW steel pipe has reached about 70% of the proportion. Our production capacity of ERW Longitudinal also occasion enhanced.