Iran Penetration Grade Bitumen made by chosen crude oils via fractional distillation process. It heated to 300-350 C. Through vaporization, fed to distillation column allowing separate lightest fractions of crude, from heavier fractions, which remain liquid.
Higher boiling point bits are drawn ? off via heat exchanger and enter vacuum distillation column. This produces also used to manufacture some grades of Iran bitumen.
Furthermore, pressure and temperature conditions within vacuum process will determine short residue hardness. It can also modified by air blowing. Air is passed throe residue at 250 ? 300 degrees C.
the grades are: 10/20, 30/40, 35/50, 40/50, 40/60, 60/70, 80/100, 100/150, 160/220