Identification Method Of Welded Steel Pipe And Seamless Steel Pipe (Up)

1. Metallographic Method

Metallography is one of the main methods to distinguish between black carbon welded steel pipe and seamless steel pipe. High-frequency resistance welded steel pipe does not add welding materials, so the welded steel pipe has a narrow weld seam. If rough grinding and corrosion are used, the weld seam cannot be clearly seen. Once the welding of high-frequency resistance welded steel pipes is completed without heat treatment, the weld structure will be essentially different from the steel pipe parent material. At this time, metallographic methods can be used to distinguish between welded steel pipes and seamless steel pipes. In the process of distinguishing the two steel pipes, a small sample with a length and width of 40mm needs to be cut at the welded place, roughened, finely ground and polished, and then placed under a metallographic microscope to observe the structure. When ferrite and weirdite, base metal and weld zone structure are observed, welded steel pipes and seamless steel pipes can be accurately distinguished.

Seamless Steel Pipe

2. Corrosion method

In the process of identifying the welded steel pipe and seamless steel pipe by the corrosion method, the sanding process should be performed at the welded seam of the processed welded steel pipe. After the sanding is completed, the polished traces should be visible, and then at the welded seam. Sand the end surface with sandpaper and treat the end surface with a 5% nitric acid alcohol solution. If an obvious weld appears, it can be proved that the steel pipe is a welded steel pipe. However, there was no significant difference in the end faces of seamless steel pipes after corrosion.

Properties of welded steel pipes

Since welded steel pipes are processed by high-frequency welding, cold rolling and other processes, they have the following properties.

First, the insulation function is good. The degree of heat loss of welded steel pipe is relatively small, only 25%, which not only facilitates transportation, but also reduces costs.

Secondly, it is waterproof and corrosion-resistant. During the construction of the project, it is not necessary to set a separate pipe trench. It is only necessary to bury the steel pipe directly underground or underwater, thereby reducing the difficulty of the project construction.

Third, it has impact resistance. Even in low temperature environment, the steel pipe will not be damaged, so its performance has certain advantages.

Performance of seamless steel pipe

Galvanized welded steel pipe supplier china believes that: due to the high tensile strength of seamless steel pipe metal materials, its resistance to damage is stronger, and because it has hollow channels, it can effectively transport fluid Because of its strong conveying capacity, the corrosion resistance of seamless steel pipes is higher than that of welded steel pipes, and its stiffness is relatively large. Therefore, the more loads the seamless steel pipe carries, it can be widely used in projects with high construction requirements.