What is spiral steel tube?

　　Welded steel pipes are steel pipes made by bending and forming steel plates or steel strips. The production process of welded steel pipe is simple, the production efficiency is high, the types are standard, and the equipment is less invested, but the general strength is lower than that of seamless steel pipe. Since the 20th century, with the rapid development of high-quality strip continuous rolling and the advancement of welding and inspection skills, the quality of welds has been continuously improved, the types of welded steel pipes have become more and more standard, and more and more areas have replaced seamless Steel Pipe. Welded steel pipes are divided into straight welded pipes and spiral welded pipes by way of welds. Straight seam welded pipe production process is simple, high production efficiency, low cost, and faster development. The strength of the spiral welded pipe is generally higher than that of the straight welded pipe. It is possible to produce a welded pipe with a large diameter by using a narrow blank, and it is also possible to produce a welded pipe having a different pipe diameter by using a blank of the same width. However, compared with the straight pipe of the same length, the length of the weld is 30-100%, and the production speed is low. Therefore, most of the smaller diameter welded pipes are straight seam welded, and the large diameter welded pipes are mostly spiral welded.

　　1. Welded steel pipe for low-pressure fluid transportation (gb/t3092-1993) is also called general welded pipe, commonly known as black pipe. It is a welded steel pipe used to transport general lower pressure fluids and other uses such as water, gas, air, oil and heating steam. The thickness of the steel pipe is divided into general steel pipe and thick steel pipe; the receiving end mode is divided into non-threaded steel pipe (light pipe) and threaded steel pipe. The standard nominal diameter (mm) of steel pipes indicates that the nominal diameter is an approximation of the inner diameter. It is customary to use inches, such as 11/2. In addition to direct use for transporting fluids, welded steel pipes for low-pressure fluid transport are also used as raw pipes for galvanized welded steel pipes for low-pressure fluid transport.

　　2. Galvanized welded steel pipe for low-pressure fluid transportation (gb/t3091-1993) is also called galvanized electric welded steel pipe, commonly known as white tube. It is a hot dip galvanized (furnace welded or electric welded) steel pipe used to transport water, gas, oil, heating steam, warm water and other general lower pressure fluids or other uses. The thickness of the steel pipe is divided into general galvanized steel pipe and thick galvanized steel pipe; the receiving end mode is divided into non-threaded galvanized steel pipe and threaded galvanized steel pipe. The standard nominal diameter (mm) of steel pipes indicates that the nominal diameter is an approximation of the inner diameter.