Structural pipe

　　Structural pipe is a variety of non-circular cross-section of the steel pipe. The main are: square tube, rectangular tube, oval tube, flat oval tube, semi-circular tube, hexagonal tube, hexagonal inner tube, unequal hexagonal tube, equilateral triangle tube, pentagonal tube, octagonal tube, convex Shaped pipe, double convex pipe. Double-concave tube, multi-concave tube, melon-shaped tube, flat tube, diamond tube, star tube, parallelogram tube, ribbed tube, drop tube, inner fin tube, twisted tube, B-tube, D Type tube and multi-layer tube.