方管，是方形管材的一种称呼，也就是边长相等的的钢管。在抗弯、抗扭强度相同时，重量较轻，所以广泛用于制造机械零件和工程结构。

Square pipe is a form of address for square pipe, that is, steel pipe with equal side length. When the bending and torsional strength are the same, the weight is lighter, so it is widely used in manufacturing mechanical parts and engineering structures.