[1] Drag reducing agents can be broadly classified [2] under the following four categories – Polymers, Solid-particle suspensions, Biological additives, and Surfactants.
Because of this, the drag reducing agent is re-injected after points like pumps and turns, where the pressure and temperature can be extra high.
This problem can be solved easier than degradation though, by adding another chemical, such as aluminum to help lower the drag reducing agent's inter-molecular attraction.
The earliest works that recorded a decrease in pressure drop during turbulent flow were undertaken in the thirties[6][7][8] and concerned the transportation of paper pulp.
A. Toms[9] was the first to recognize the tremendous reduction in wall shear stress caused by the addition of small amount of linear macromolecules to a turbulent flowing fluid.
[10] Drag reducers were introduced into the market in the early 1970s by Conoco Inc.[11] (now known as LiquidPower Specialty Products Inc. (LSPI), a Berkshire Hathaway company).
The higher flow rates possible on long pipelines have also increased the potential for surge on older systems not previously designed for high velocities.
Both proprietary (such as Conoco T-83) and non-proprietary (such as poly-isobutylene) drag reduction additives have been evaluated by the U.S. Army Mobility Equipment Research and Development Center for enhancement of military petroleum pipeline systems.