Seamless pipe type

SMLS pipe type is as follows:

1. According to different production methods, seamless steel pipes can be divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, and extruded pipes.

a) Hot rolled steel refers to all kinds of hot rolled steel produced by the method of hot rolling. Most steel products are made by hot rolling. Hot rolling is commonly used to produce large steel products such as section steel, seamless steel tubes, steel plates, etc., and is also used to roll wire rods.

b) Cold rolled steel refers to all kinds of cold rolled steel produced by cold drawing method. Compared with hot-rolled steel, too much cold-rolled steel has a smooth surface and precise dimensions. The mechanical properties are good. Cold rolling is commonly used to roll thin plates, steel strips and seamless steel pipes.

c) Cold drawn steel refers to all kinds of cold drawn steel produced by the cold drawing method. The characteristics of cold drawn steel are: high precision and good surface quality. Cold drawing is mainly used to produce steel wire, but also used to produce round steel alloy hexagonal steel with a diameter of less than 50mm, and steel pipes with a diameter of less than 76mm.

d) Extruded pipes are pipes produced by cold extrusion, hot extrusion, and warm extrusion processes.

2. According to the shape, there are round pipes and special-shaped pipes. In addition to square tubes and rectangular tubes, special-shaped tubes include oval tubes, semicircular tubes, triangular tubes, hexagonal tubes, convex-shaped tubes, plum-shaped tubes, etc.
3. According to different materials, it can be divided into ordinary carbon structure tube, low alloy structure pipe, high quality carbon structure pipe, alloy structure pipe, stainless steel pipe, etc.
4. According to the special purpose, there are seamless boiler tubes, geological tubes, oil tubes, etc.

The various standards implemented by seamless steel pipes stipulate the requirements for the "surface finish" of seamless steel pipes. What are the common defects on the surface of seamless steel pipes?

Common defects are: cracks, hair lines, internal folds, external folds, crushing, internal straights, external straights, separation, scars, pits, convex hulls, pits (pits), scratches (abrasions) , inner spiral, outer spiral, blue line, concave correction, roll printing, etc. Among them, cracks, internal folds, external folds, rolling, separation, scars, pits, convex hulls, etc. are dangerous defects; seamless steel pipe pitted surface, blue line, scratches, slight internal and external straight, slight internal and external Spiral, concave correction, and roll printing are general defects.