What are the requirements for the quality of tube blanks in the production of precision and cold drawn seamless steel tubes?

(1) Structural seamless steel pipe and conveying pipe blank. Including low carbon steel, medium carbon steel and alloy structural steel tube billet, steel number has 10#, 20#, 35#, 45#, and 15Cr, 40Cr, 30CrMnSi, 12CrMoV and so on.

（2） Boiler tube blank. Generally, the steel for boiler tube blanks is low carbon steel and high quality carbon structural steel. For example, 10#, 20#, 20A, in order to mark the steel for boiler tube billet, you can add “pot” or “G” after the steel number. Such as 20 pots or 20G.

(3) Oil drilling and geological drilling pipe blanks. Such steel for tube blanks includes medium carbon steel, low alloy steel and alloy steel. This type of tube blank is delivered in steel grade according to mechanical properties, and "DZ" is added before the steel number, such as DZ55, DZ80.

(4) Fertilizer and fertilizer pipe blanks. Chemical equipment and pipe transportation pipe billet steels are carbon steel, heat-resistant and acid-resistant stainless steel, such as 20#, 1Cr18Ni9Ti; petroleum cracking pipes are made of carbon steel and alloy steel, such as 10#, 20#, 12Mn2, Cr5Mo, 12CrMoV; fertilizer Pipe steel has carbon steel and alloy steel, etc.

(5) Other special tube blanks.

Qualified tube blanks are a prerequisite for the production of cold drawn seamless steel tubes. Due to the deformation characteristics of the cross-rolling perforation, strict technical requirements are imposed on the quality of the tube blank (especially the surface quality).

（In this hot summer, our workers are still working very hard in the workshop, and all the orders are coming over!）

According to the ministerial standards, there are certain technical requirements for the size, surface quality and organization of the blanks made of high-quality round steel.

(1) Geometric dimensions and allowable deviation of cold drawn seamless steel tube blanks:

Tube blank diameter and tolerance:

When the diameter of the blank is 75 mm, the allowable deviation is +1.0 -0.5 mm;

When the diameter of the tube blank is 80~90 mm, the allowable deviation is +0.8-1.3 mm;

The allowable deviation is from +1.0 to 1.7 mm when the tube blank is 95 to 120 mm in diameter.

Tube length: generally 2.3~6 meters (according to mutual agreement).

Bending: The local bending is not more than 10 mm per meter without straightening equipment, and the total bending is not more than 1.0% of the total length.

Tube blank head chamfer:

When the diameter of the pipe is not more than 96 mm, the inclination is less than 6 mm;

When the tube blank is 95 to 120 mm in diameter, the cutting slope is less than 8 mm.