Spiral pipes, also known as spiral steel pipes or spiral welded pipes, are made by rolling low-carbon structural steel or low alloy structural steel strips at a certain helix angle (called forming angle) into pipe blanks, and then welding the pipe seams together. It can produce large-diameter steel pipes from narrower strip steel.

Also known as a spiral tube or spiral body. The outer diameter of the spiral tube is about 30 micrometers, the inner diameter is about 10 micrometers, and the spacing between adjacent spirals is about 11 micrometers. The spiral tube is surrounded by six nucleosome every week. H1 histones are located on the inner surface of the spiral tube cavity and play an important role in maintaining the structure of the spiral tube. The 10 nm fiber composed of nucleosome spirals to form 30 nm thick fiber, further compressing the length of DNA by 6 times.