The fluid pipeline is a steel pipe with hollow section and no weld from beginning to end. Steel pipe has hollow section and is used as a pipeline for transporting a large amount of oil, natural gas, natural gas, water and some solid materials. Compared with solid steel (such as round steel), when the bending and torsional strength are the same, the weight of steel pipe is lighter. It is a kind of economical section steel, which is widely used to manufacture structural parts and mechanical parts such as oil drill pipe, automobile transmission shaft, bicycle and so on. Scaffolds and steel scaffolds used in construction. (for example, API 5L hot rolled steel pipe, API 5L grade B Sch 40 80 160, API 5lx52 seamless steel pipe, API 5lx52 seamless) requirement; When the welded pipe is used as a fluid transmission pipe, it has different requirements from the ordinary steel pipe: 1. No leakage is allowed for welds. For welded pipes required by API, ultrasonic flaw detection and h…