The seamless steel pipe is one kind has the midheaven section, peripheral joint sliver of steel products. The steel pipe has the midheaven section, serves as the conveyance fluid massively the pipeline, like transportation petroleum, natural gas, coal gas, water and certain solid material pipeline and so on. Solid steel products and so on steel pipe and round steel compare, when the anti-curved resistance to torsion is the same, the weight is light, is one kind of economical section steel products, widely uses in making the structural element and the machine parts, like the petroleum drill rod, the automobile drive shaft, in the bicycle rack as well as the building construction uses steel scaffold and so on. With the steel pipe manufacture ring-like components, may raise the high material use factor, the simplified manufacture working procedure, saves material and the processing man-hour, like the rolling bearing ferrule, the hoisting jack set and so on, broad pan-has made at present with the steel pipe. The steel pipe each kind of conventional weapons essential material, the barrel, the artillery tube and so on wants the steel pipe to make. Steel pipe different may divide into the circular pipe and the heterogeneous tube according to the plan area shape. Because under the perimeter equal condition, the round area is biggest, may transport more fluids with round tube . In addition, ring section when withstanding interior or exterior radial thrust, the stress is even, therefore, big the most steel pipes are the circular pipes certainly.
