LSAW (Longitudinally Welded SAW Pipe) DSAW(Double submerged arcweld) Lsaw (Longitudinally welded saw pipe) DSAW(double submerged arcweld)
A welded pipe (a pipe with a weld) is a tubular product made of a flat plate (called a skeleton) that is shaped, bent, and prepared for welding. The most popular process for large diameter pipes is longitudinal seam welding. Double submerged arc welding (DSAW) pipe is a pipe with at least two welds in the longitudinal butt joint, one of which is welded on the inside of the pipe; Welding is performed by arc heating between bare metal electrodes. No pressure is used. The filler metal for the weld is obtained from the electrode. For pipes larger than 36 inches in diameter, double-seam welded pipes are specified in API 5L as alternative pipes. It has two longitudinal joints separated by 180°, formed by the SAW process. The finished pipe is usually 40 feet (12 m) long and sometimes 60 feet (18 m) long, depending on the capacity of the pipe plant and the ease of pipe transportation.
Spiral pipe Spiral welded pipe
As an alternative process, spiral welded construction allows the production of large diameter pipes from narrower sheets or frames. The defects in spiral welded pipe are mainly related to submerged arc welding seams, which are essentially similar to the defects in straight seam submerged arc welded pipe. Another problem with early spiral welded pipes was poor dimensional accuracy, especially the unroundness of the pipe ends. This has led to problems with poor assembly during on-site ring welding. As a result of these early experiences, spiral line pipes had a bad reputation among some companies and were considered only suitable for low-pressure applications, such as water pipes. However, modern spiral line pipes from premium suppliers are of comparable quality to straight welded pipes and have been widely used in Canada and Europe for high pressure natural gas lines up to API X70.
