Alien seamless steel pipe is besides other than the cross-section shape of seamless steel tube. According to the different shape steel section size and thickness can be divided as abnormal seamless steel tube (D), codenamed range wall thickness alien seamless steel tube (BD), codenamed abnormal seamless steel tube diameter (code-named "BJ"). Alien seamless steel tube is widely used for various structural, tools and machinery spare parts. Compared with pipe, tube generally have large inertia and section modulus, have bigger bending wrest resistant capability, can reduce weight, managing steel structure. Irregular pipe is commonly according to break to differentiate, according to section materials can be divided into the seamless steel tube, aluminum alloy irregular pipe aliens, plastic profiled tube. Mainly introduce below steel tube. Abnormal Steel pipe can be divided into the oval alien profiled steel tube, hexagons, triangle profiled steel tube, lozenge alien profiled steel, hemicycle, octagonal alien, special-shaped steel round profiled steel tube, five equilateral hexagon steel, the plum flower form abnormal double double convex profiled steel tube, double concave profiled steel tube, abnormal shape, melon seeds, corrugated steel cone shape abnormal abnormal tube. Irregular pipe, alien square tubes, torque irregular pipe, tube welding, spiral welded pipe, specifications: 20 * 20mm - 500mm, 0.6 mm - 20mm thick wall, spiral pipe. 219mm spiral pipe specifications, 2020mm - 5mm - 20mm thick wall, straight stitch specifications. 4, 6, and 1 inch, 1.2 inches, 1.5 inches, 2 inches, 2.5 inches, 3, 4, 5, 6, 8 inches, 102, 108, 127, 133, 139, 159, 168, 177, 194, 219, 273, 325 etc more commonly irregular pipe specifications refers to the party rectangular tubes