Seamless steel pipe is a round, square and rectangular steel with a hollow section and no joints around it. Seamless steel pipes are made of steel ingots or solid tube blanks through perforation to make capillaries, which are then hot-rolled, cold-rolled or cold-drawn. The seamless steel pipe has a hollow section and is widely used as a pipeline for conveying fluid. Compared with solid steel such as round steel, the steel pipe has a lighter weight when the bending and torsional strength is the same.