Special-shaped seamless steel tube is the general name of seamless steel tube with other cross-sectional shapes except circular tube. According to the different cross-sectional shapes and sizes of steel pipes, they can be divided into special-shaped seamless steel pipes with equal wall thickness (code D), special-shaped seamless steel pipes with unequal wall thickness (code BD) and special-shaped seamless steel pipes with variable diameter (code BJ).
This is an economical steel pipe. Including non-circular cross-sectional profile, equal wall thickness, variable wall thickness, variable diameter and variable wall thickness along the length direction, symmetrical and asymmetrical cross-sections, etc. Such as square, rectangle, cone, trapezoid, spiral, etc.
Special-shaped steel pipe can better adapt to the particularity of service conditions, save metal and improve the labor productivity of parts manufacturing. Widely used in aviation, automobile, shipbuilding, mining machinery, agricultural machinery, construction, textile and boiler manufacturing. The methods of producing special-shaped pipes include cold drawing, electric welding, extrusion and hot rolling. Among them, cold drawing method has been widely used.