Small-diameter thick-walled steel pipes refer to pipes with an outer diameter less than 630mm and an outer diameter-to-thickness ratio less than 20. Currently, the smallest diameter available is 3mm, with the wall thickness as thin as 1mm.
Small-diameter thick-walled steel pipes are commonly used in double-sided submerged arc welding production processes. The products undergo multiple processes such as bending, jointing, internal welding, external welding, straightening, and flatening to meet the requirements of the American Petroleum Institute standards. Large-diameter thick-walled steel pipes are mostly applied in large-scale steel structure construction, serving as the main support, such as bridge pile driving, offshore pile driving, and high-rise building pile driving.
Materials are generally selected as 20# and Q345B.