Wax or paraffin deposition refers to the accumulation of

paraffin wax Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and begins to m ...

on the surface of a substance, typically a liquid or gas. This can occur in a variety of contexts, including the production and transport of oil and natural gas, the refining of petroleum products, and the storage and transport of chemicals. For the transportation of crude oil in a pipeline, wax can deposit on to the inner surface of the pipeline, reducing the area for fluid to flow and increasing the pressure requirement for fluid to flow. To prevent wax deposition, various techniques can be used, including heating the fluid to dissolve wax back into the oil phase, adding chemicals to prevent wax formation, and using specialized equipment or a

pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus s ...

to remove the wax deposit from the pipe wall surface. The term "wax deposition" should not be confused with the term "wax precipitation". The precipitation of wax refers to the phase change of the dissolved wax in liquid phase into solid wax particles. This phenomenon is governed by the

thermodynamic equilibrium Thermodynamic equilibrium is an axiomatic concept of thermodynamics. It is an internal state of a single thermodynamic system, or a relation between several thermodynamic systems connected by more or less permeable or impermeable walls. In thermod ...

of wax in oil. The wax precipitation is the

necessary condition In logic and mathematics, necessity and sufficiency are terms used to describe a conditional or implicational relationship between two statements. For example, in the conditional statement: "If then ", is necessary for , because the truth of ...

, but it is not the sufficient condition for wax deposition to occur. For wax deposition to occur, the solid surface temperature for wax to be deposited on must be lower than the temperature of waxy oil solution.

References

Precipitation Deposition (geology) {{Petroleum-stub