Large caliber welded steel pipes refer to steel pipes with welded joints, mainly made of steel plates and steel strips. Large caliber straight seam welded steel pipes use steel plates, which have high production efficiency and low cost and are currently one of the most commonly used steel pipe products.

Welded steel pipe refers to a steel pipe with joints on its surface, which is formed by bending and deforming steel strips or plates into circular, square, or other shapes before welding. The production process of welded steel pipes is simple, the production efficiency is high, there are many varieties and specifications, and the equipment resources are limited, but the strength is generally lower than that of seamless steel pipes. Since the 1930s, with the rapid development of high-quality strip steel continuous rolling production and advances in welding and inspection technology, the quality of welds has been continuously improved, and the variety and specifications of welded steel pipes have been increasing in more and more fields

According to different welding methods, it can be divided into arc welded pipes, high-frequency or low-frequency resistance welded pipes, gas welded pipes, furnace welded pipes, Bondi pipes, etc. According to the shape of the weld seam, it can be divided into straight seam welded pipe and spiral welded pipe.

Generally, welded pipes are used to transport low-pressure fluids. Made of Q195A, Q215A, Q235A steel. Other soft steel materials that are easy to weld can also be used for manufacturing. Steel pipes need to undergo tests such as water pressure, bending, and flattening, and there are certain requirements for surface quality. The delivery length is usually 4-10m, and it is often required to be delivered to a fixed length (or multiple length). The specifications of welded pipes are expressed in nominal diameter (millimeters or inches). The nominal diameter is different from the actual one. Welded pipes are divided into two types according to the specified wall thickness: ordinary steel pipes and thickened steel pipes. Steel pipes are further divided into threaded and non threaded types according to the pipe end form.

Large caliber welded steel pipes generally use double-sided submerged arc welding technology, which can be divided into large-diameter straight seam steel pipes and large-diameter spiral steel pipes according to the different welds. Among them, straight seam steel pipes can be further divided into UOE, RBE, JCOE steel pipes, etc. according to the different forming methods. The production process of large-diameter straight seam steel pipes is simple, with high production efficiency and low cost. However, the strength of large-diameter spiral steel pipes is generally higher than that of straight seam steel pipes. They can produce steel pipes with larger diameters using narrower billets, and can also produce steel pipes with different diameters using billets of the same width. However, the production efficiency is relatively low compared to that of welded steel pipes. Large diameter steel pipes are mainly used in large-scale pipeline engineering, water and gas transmission engineering, urban pipeline construction, municipal engineering, water supply and drainage engineering, and large building steel structures