Galvanized steel pipe, also known as GI steel pipe, can classified into two kinds. One is hot dipped galvanized steel pipe, the other is electric steel pipe. Advantage of hot dipped galvanized steel pipe is that the galvanized coating will be thicker, and the zinc coating will be fairly and can stick to the pipe body better. And life span of hot dipped galvanized steel pipe is longer. For electric steel pipe, the cost will be cheaper than hot dipped galvanized steel pipe, but it also has its disadvantage. The surface of the electric steel pipe is not smooth. And its anti-corrosion function is not as good as hot dipped galvanized steel pipe. In order to approve steel pipes quality and extend its life span, galvanized steel pipe is widely used in our daily life. We can see that GI steel pipe is widely used for transport gas, heat, water pipe, and for construction usage. And most of scaffolding are GI steel pipe.