Welded pipes, also known as welded steel pipes, are steel pipes made by welding steel plates or strips after rolling and forming. The production process of welded steel pipes is simple, with high efficiency, a wide variety of specifications, and low equipment investment, although their strength is generally lower than that of seamless steel pipes. Welded steel pipes are categorized by the type of weld, into straight seam and spiral seam pipes. By production method, they are classified as: arc-welded pipes, resistance-welded pipes, (high-frequency, low-frequency) gas-welded pipes, and furnace-welded pipes. The production process of straight seam pipes is simple, with high efficiency, low cost, and rapid development.

Spiral-welded pipes generally have higher strength than straight seam welded pipes, allowing for larger pipe diameters to be produced from narrower billets. Additionally, pipes of different diameters can be produced from the same width billets. However, compared to straight seam pipes of the same length, the weld length increases by over 30%, and the production speed is slower.