Seamless Steel Pipe

Seamless steel pipe is a long steel pipe with hollow sections and has no joints surrounding the steel bar. It is mainly used as a pipeline to transfer the fluid, such as oil, natural gas, water and some solid materials, etc. As compared to the flexural torsional strength in the same light, it is an economic cross-section steel. The seamless steel pipes are widely used in the manufactures and mechanical parts, such as the oil pipe, automotive transmission shaft, bicycles aircraft, as well as building construction. With steel pipe manufacturing, annular parts can improve the material utilization, simplify the manufacturing process, and save material and machining time. For example, the roller bearing rings and the jack sets and so on have been widely made of steel pipes. Cylindrical rubes can delivery more fluid since the circle has the largest areas under the same circumference. In addition, the ring cross-section bears internal or external pressure, the force more evenly, so that vast majority of tubular steel pipes are cylindrical rubes. However, the tube also has some limitations, such as in-plane bending conditions, the pipe on the better side, rectangular tube bending strength, and a number of sets of frames, steel-wood furniture on the commonly used square, rectangular tube.

The pressure of seamless steel pipe is generally composed of pieces of standard parts, so the pressure pipe design component is the selection of its standard parts. The pressure level of pipelines is determined to the pressure level of its standard parts.

Pipeline pressure level consists of two parts: One is nominal pressure rating which is expressed in the Nominal pressure of the standard parts. The other is wall thickness rating which is expressed in the wall thickness of the stand parts.

The pressure grade of the pipes: The parameters of channels characteristics which are determined by the nominal pressure level and wall thickness are called the pressure grade of seamless steel pipe. To simplify the description, we often call the nominal pressure rating as pipe pressure grades.

The calculation of the pressure grades is not only the basis for pipeline design, but also the core of design. It is the basis of the arrangement of pressure pipe, and pressure pipe stress precondition for checking the design. And it is also an important factor which will affect investment in infrastructure and reliability of pipelines.