Discrimination method of welded steel pipe and seamless steel pipe

1. Distinguish welded steel pipes and seamless steel pipes according to the process.

In the process of identifying welded steel pipes and seamless steel pipes according to the process, all-welded steel pipes are welded according to cold rolling, extrusion, and other processes. Spiral pipe welding and straight seam pipe welding will form round steel pipes, square steel pipes, oval steel pipes, triangular steel pipes, hexagonal steel pipes, diamond steel pipes, octagonal steel pipes, and even more complex steel pipes. In short, the use of different processes will form steel pipes of different shapes, so that welded steel pipes and seamless steel pipes can be distinguished. However, in the process of identifying seamless steel pipes according to the process, it is mainly distinguished according to the hot-rolled and cold-rolled processing methods, and there are two main forms of seamless steel pipes, namely hot-rolled seamless steel pipes and cold-rolled seamless steel pipes. Hot-rolled seamless steel pipes are formed by perforating, rolling, and other processes, especially large-diameter and thick seamless steel pipes are welded by this process; cold-drawn pipes are cold-drawn with tube blanks, and the strength of the material is lower. But its exterior and interior control surfaces are smooth.

2. Distinguish welded steel pipes and seamless steel pipes by application.

Welded steel pipes have higher bending and torsional strength and more load-bearing capacity, so they are generally widely used in the manufacture of mechanical parts. For example, oil drill pipes, automobile drive shafts, bicycle frames and steel scaffolding used in construction are all made of welded steel pipes. However, seamless steel pipes can be used as pipes for conveying fluids because they have a hollow cross-section and are long strips of steel without joints around them. For example, it can be used as a pipeline for transporting oil, natural gas, gas, water, etc. In addition, the bending strength of seamless steel pipe is relatively small, so it is generally widely used in superheated steam pipes for low and medium pressure boilers, boiling water pipes, and superheated steam pipes for locomotive boilers. In short, through the classification of uses, welded steel pipes and seamless steel pipes can be distinguished.

To ensure a higher quality of engineering construction in my country, it is necessary to distinguish between welded steel pipes and seamless steel pipes, and then use suitable steel pipes for construction. In the process of identifying welded steel pipes and seamless steel pipes, metallographic and corrosion methods can be used to inspect the welds by observing the structure and welds, and finally identify them accurately. At the same time, two kinds of steel pipes can be distinguished according to their properties and uses, and then a reasonable steel pipe can be selected for construction.