Seamless furnace pipe refers to the two ends of the opening and has a hollow section, its length and the perimeter of the larger steel, according to the production method can be divided into seamless steel pipe and welded steel pipe, the specifications of the steel pipe with the external dimensions (such as the outer diameter or side length) and wall thickness, which is a wide range of sizes, from the diameter of the very small capillary tube up to the diameter of up to a few meters of the large diameter pipe. Steel pipes are used in pipelines, thermal equipment, mechanical industry, petroleum and geological exploration, containers, chemical industry and special applications.

Classification of steel pipe: steel pipe is divided into two categories: seamless steel pipe and welded steel pipe (seamed pipe). According to the sectional shape can be divided into round and shaped pipe, widely used is round steel pipe, but there are some square, rectangular, semi-circular, hexagonal, equilateral triangle, octagonal and other shaped steel pipe. For bearing fluid pressure steel pipe should be hydraulic test to check its pressure resistance and quality, in the specified pressure does not leak, wetting or swelling for qualified, some steel pipe also according to the standard or demand side requirements for crimping test, flaring test, flattening test, and so on.