Cold drawn carbon steel pipe

Cold rolling involves processing steel plates or strips into various types of steel products through cold working methods such as cold drawing and cold bending at room temperature.

Categories of Carbon Steel Pipes

Carbon steel pipes are divided into two main categories: hot-rolled and cold-rolled (or cold-drawn) steel pipes. These pipes are produced by perforating steel ingots or solid billets into capillary tubes, which are then further processed through hot rolling, cold rolling, or cold drawing. Carbon steel pipes play a significant role in the steel pipe industry.

Cold Rolled Carbon Steel Pipes

Cold rolled carbon steel pipes are precision seamless steel pipes created through cold drawing or cold rolling. These pipes are used in mechanical structures and hydraulic equipment, requiring high dimensional accuracy and a good surface finish. Apart from general steel pipes, cold-rolled (or cold-drawn) seamless pipes include:

Low and medium pressure boiler steel pipes

High pressure boiler steel pipes

Alloy steel pipes

Stainless steel pipes

Petroleum cracking pipes

Carbon thin-walled steel pipes

Alloy thin-walled steel pipes

Stainless thin-walled steel pipes

Special-shaped steel pipes

The outer diameter of hot-rolled seamless pipes generally exceeds 32 mm with wall thicknesses between 2.5 to 75 mm. In contrast, cold-rolled seamless pipes can have diameters as small as 6 mm and wall thicknesses as thin as 0.25 mm, offering higher dimensional accuracy than hot-rolled pipes.

Hot Rolled Steel Pipes

Hot rolled steel pipes are categorized into various types, including:

General steel pipes

Low and medium pressure boiler steel pipes

High pressure boiler steel pipes

Alloy steel pipes

Stainless steel pipes

Petroleum cracking pipes

Geological steel pipes

General Carbon Steel Pipes

These pipes are manufactured from high-quality carbon steels such as 10, 20, 30, 35, 45, low-alloy structural steels like 16Mn, 5MnV, and alloy steels including 40Cr, 30CrMnSi, 45Mn2, 40MnB. Seamless pipes made from low carbon steels such as 10 and 20 are primarily used for fluid transportation pipelines. Medium carbon steel seamless pipes, such as those made from 45 and 40Cr, are used for manufacturing mechanical parts like stressed components in automobiles and tractors. These carbon steel pipes undergo strength and flattening tests to ensure quality. Hot-rolled pipes are delivered in a hot-rolled or heat-treated state, while cold-rolled pipes are delivered in a heat-treated state.

Differences Between Cold Rolling and Hot Rolling

Local Buckling:

Cold-rolled section steel allows local buckling of the section, enabling full utilization of the member's bearing capacity after buckling.

Hot-rolled section steel does not allow local buckling of the section.

Residual Stress:

The reasons for residual stress in hot-rolled and cold-rolled steel differ, leading to different distribution patterns across the cross-section.

In cold-formed thin-walled steel, residual stress distribution is curved, while in hot-rolled or welded steel, it is thin-film.

Torsional Stiffness:

Hot-rolled steel has higher free torsional stiffness compared to cold-rolled steel, resulting in better torsion resistance in hot-rolled steel.