The difference between spiral welded pipe and straight seam submerged arc welded pipe
The main difference between spiral welded pipe and longitudinal welded pipe is the difference in welding form. Spiral welded pipe is to roll low carbon structural steel or low alloy structural steel strip at a certain helix angle (also called forming angle) into a tube blank, and then weld it to form a pipe seam. Large diameter pipes can be produced from narrow strip steel. Spiral welded pipes are mainly spiral submerged arc welded pipes (SSAW), which are frequently used in the construction of various gas pipelines in my country. Its specifications are represented by "outer diameter * wall thickness". Spiral welded pipe has single-sided and double-sided welding. The welded pipe shall ensure that the hydrostatic test, tensile strength and cold bending performance of the weld meet the requirements.
The straight seam welded pipe is a high frequency straight seam welded pipe (ERW), after the coil is formed by the forming machine before welding, it is melted by the proximity effect generated by the high frequency current and the solder layer, and then melted by a certain extrusion force, and then cooled to form , in which the edge of the tube blank is melted by high-frequency current and arc welded, called straight seam submerged arc welded pipe (LSAW).
The strength of spiral welded pipe is generally higher than that of straight welded pipe, and the main production process is submerged arc welding. Spiral welded pipes can use blanks of the same width to produce welded pipes of different diameters, and can also use narrower blanks to produce welded pipes with larger diameters.
The production process of straight seam submerged arc welded pipe is relatively simple, mainly divided into high frequency welded longitudinal welded pipe and submerged arc welded longitudinal welded pipe. Straight seam welded pipe has high production efficiency, low cost and rapid development.
However, compared with the longitudinal welded pipe of the same length, the length of the weld is increased by 30~100. The production speed is lower. Therefore, welded pipes with smaller diameters are mostly longitudinally welded, while those with larger diameters are mostly spiral welded pipes.