Production Tubing - is a pipe that is inserted into a cased hole (wellbore), through which hydrocarbons are transported (produced) to the surface. Production tubing comes in various sizes and varies between ¾” to 4 ½”. Production tubing also serves as a protection of the well casing against corrosive fluids, sand, paraffin and wear & tear. Together with other completion components, it is also called Production String. If production tubing is damaged, it can easily be replaced, which is not the case with the well casing.