Welded steel pipes, also known as welded pipes, are made of steel plates or steel strips that are welded after being crimped and formed.
The production process of welded steel pipe is simple. The manufacturer’s production efficiency is high. There are many varieties and specifications. The equipment investment is less, but the general strength is lower than that of seamless steel pipe. Since the 30s of the 20th century, with the rapid development of high-quality strip continuous rolling production and the progress of welding and inspection technology, the quality of welds has been continuously improved. The varieties and specifications of welded steel pipes have increased day by day, and seamless steel pipes have been replaced in more and more fields.

Welded steel pipes are divided into longitudinal welded pipes and spiral welded pipes according to the form of welds. The production process of longitudinal welded pipe is simple, the production efficiency is high, the cost is low, and the development is fast. The strength of spiral welded pipes is generally higher than that of longitudinal welded pipes, and welded pipes with larger diameters can be produced with narrower blanks. Welded pipes with different diameters can also be produced with blanks of the same width. However, compared with the same length of straight seam pipe, the weld length is increased by 30~100%, and the production speed is lower. Therefore, most of the smaller-diameter welded pipes are welded longitudinally, while the larger-diameter welded pipes are mostly spiral welded.