I-beams are mainly divided into ordinary I-beams, light I-beams and wide-flange I-beams. According to the height ratio of flange to web, it is divided into wide, medium and narrow wide flange I-beams. The first two are produced in sizes 10-60, that is, the corresponding heights are 10 cm-60 cm. At the same height, lightweight I-beams have narrow flanges, thin webs, and light weight. Wide-flange I-beam is also called H-beam. The cross-section feature is that the legs are parallel and there is no slope on the inside of the legs. It is an economical section steel and is rolled on a four-roll universal rolling mill, so it is also called "universal I-beam". Ordinary I-beams and light I-beams have formed national standards.