Seamless cold-drawn steel pipes are divided into two types: round and special-shaped according to the shape of the longitudinal section. Special-shaped pipes include rectangle, square, semicircle and various polygons. Cold drawn square tubes are widely used. The general-purpose seamless square tube is rolled from ordinary carbon structural steel, low-alloy structural steel or alloy structural steel.
There are three types of supply according to different operating temperatures:
a. Hot rolling (extrusion seamless):
High-quality carbon structural steel, alloy structural steel and stainless and acid-resistant steel seamless steel pipes for the manufacture of high-pressure and above steam boiler pipes;


b. Cold drawn (rolled) seamless):
High-quality carbon structural steel, stainless acid-resistant steel and Heat-action high-temperature structural steel inorganic salt and other seamless square tubes;


c. Cold drawn (rolled) non-standard specialization:
It is used to make various non-standard special industries and other high-strength round iron products.