The Difference Between Cold Drawn and Hot Rolled Seamless Steel

  • Seamless steel tubes are popularly used in various industries including – oil, petrochemical, energy plants, water supply, and much more. However, not all seamless pipes are made the same. There are two different types of seamless pipes based on the way they are made. These are:

    • Cold Drawn Seamless Tubes
    • Hot Rolled Seamless Tubes

    Let us take a deeper look into the two types to understand their differences.

    Cold drawn seamless tube

    Cold rolled seamless steel tubesare seamless steel tubeswith high dimensional accuracy and good surface finish. General seamless steeltubes like low and medium pressure boiler tube, high-pressure boiler tubes, alloy steel pipes, stainless steel pipes and oil cracking tubes are of cold drawn variety. Apart from these cold drawn seamless tubes also include cold drawl carbon thin wall steel pipes, thin-walled stainless steel pipes,alloy thin wall steel tube, and special-shaped steel tubes. The dimensional accuracy of cold drawn seamless steel tub is higher than that of hot rolled.

    Hot rolled seamless tube

    While cold drawn seamless pipecontinues rolling below the temperature of recrystallization, the hot rolled ones roll above the recrystallization temperature. Some examples of hot rolled seamless steel pipes are - low, medium, andhigh-pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, oil cracking pipes, geological steel pipes and other steel pipes.

    Now let us look at their differences:

    • The cold drawn seamless tube allows local buckling, making full use of bending bearing capacity. On the other hand, hot rolled steel does not allow local buckling.
    • As the causes of residual stress are different in these two types of seamless pipes, the distribution of the cross section is also very different from each other. The distribution of the residual stress on cold drawn thin wall steel is bending, whereas, the distribution of the residual stress on hot rolled steel is film type.
    • The torsion resistance of hot rolled steel pipe is higher than that of cold drawn steel pipes. In other words, the free torsional rigidity of hot rolled steel is better than that of cold drawn steel pipes.

    Despite the differences both types of seamless steel tubes are widely used in various industries. However, the industries that require dimensional accuracy in their pipes must opt for the cold drawn variety.