Hot rolled steel is the most basic form of carbon steel. However, the scale that is left behind on hot rolled steel after it is formed is undesirable in many manufacturing applications and processes. In order to combat the scale issue, mills started to pickle and oil their steel to create a more desirable product for end users.

Thus, hot rolled pickled and oiled (from here on referred to as HRPO) flat rolled steel coils were born. HRPO steel is still considered hot rolled steel even though it does not have any scale. The final product of HRPO steel is created when steel mills use acid baths to remove the scale that usually forms on the surface of carbon steel coil, as the coil is cooling.

Once the coil is bathed in acid, it is "pickled". The pickling process consist of applying dried oil to the steel's surface in order to prevent rusting. HRPO flat rolled steel is ideal for plate burning and plasma cutting processes in order to manufacture and machine smaller, more precise steel components and parts out of HRPO sheet and plate.