The main difference between the two welded pipes of spiral welded pipe and straight welded pipe is the difference in welding form.
Spiral welded pipe is a low carbon carbon structural steel or a low alloy structural steel strip rolled into a tube blank with a certain helix angle (also called forming angle), and then welded and made into a pipe joint, which can use a narrow strip steel Production of large diameter steel pipes. Spiral welded pipe is mainly spiral submerged arc welded pipe (SSAW), which is frequently used in the construction of various gas pipelines in China. Its specifications are expressed by "outer diameter * wall thickness". Spiral welded pipes are single-sided welded and double-sided welded. The welded pipe shall ensure that the hydraulic test and the tensile strength and cold bending performance of the weld are in compliance with the regulations.
The straight seam welded pipe is a high-frequency current and a proximity effect step which are to be generated by the solder layer before the welding is formed by the molding machine, and the edge of the tube blank is heated and melted, and is fused under a certain pressing force, cooling molding. The high-frequency straight seam welded pipe is used in which the edge of the pipe blank is melted by high-frequency current(ERW), which is called a straight seam submerged arc welded pipe (LSAW) by melting with an electric arc.
The strength of the spiral welded pipe is generally higher than that of the straight welded pipe. The main production process is submerged arc welding. The spiral welded pipe can produce welded pipes with different pipe diameters with the same width of blanks, and can also produce welded pipes with larger diameters with narrow blanks.
The production process of straight seam welded pipe is relatively simple, mainly in the production process, which is divided into high-frequency welded straight seam welded pipe and submerged arc welded straight welded pipe. The straight seam welded pipe has high production efficiency, low cost and rapid development.
However, compared with the straight pipe welded pipe of the same length, the weld length is increased by 30 to 100, and the production speed is low. Therefore, the smaller diameter welded pipes are mostly straight seam welded, while the large diameter welded pipes are mostly spiral welded.
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