Seamless steel tubes are used in a wide range of applications in seamless steel pipe supplier. The general-purpose seamless steel pipe is rolled from ordinary carbon structural steel, low-alloy structural steel or alloy structural steel, and has the largest output, and is mainly used as a pipe or structural component for conveying fluid. According to the use of three types of supply: a, according to chemical composition and mechanical properties; b, according to mechanical properties; c, according to water pressure test supply. Steel pipes supplied in categories a and b, if used to withstand liquid pressure, are also subjected to hydrostatic testing. Special-purpose seamless pipes include boiler seamless pipes, chemical power, geological seamless steel pipes and petroleum seamless pipes.
Cold-drawn precision seamless steel pipe production requires attention to control points:
Annealing is a very important process in the production of all cold drawn tubes. The quality of the annealing affects both the performance of the steel tube and the removal of the scale. Cold drawn precision steel tubes require a non-oxidizing bright annealing furnace equipment.
The precision seamless steel pipe is easy to form “black slag” mainly composed of Fe2O3 and Fe3O4 in the acid pickling process, and forms a black spot on the surface in subsequent production. Fe2O3 and Fe3O4 are easily soluble in hydrochloric acid, and 5-10 g/l of NaCl is added to the acid bath to prevent the formation of dark spots.
3, capillary tube
The wall thickness of the capillary tube should be uniform, and the surface defects on the inner and outer surfaces should be small; the outer surface polishing and inner hole defect cleaning equipment should be arranged.
Compared with ordinary cold drawn steel pipe, cold drawn precision seamless pipe production increases the hot-rolled capillary pickling re-inspection process, mainly to ensure that there are no defects such as folding and crack on the outer surface of the capillary tube, and the inner surface is excluded from folding and severely scribed. Tubes with defects such as pockmarks.click
Generally, the surface roughness of tools used in the production of cold drawn precision seamless steel tubes is above Ra0.4, the dimensional accuracy is above H3, and the hardness is required to be above HRC70. At the same time, it is required that the tip or mold sticking phenomenon does not occur during the drawing process.