Coating mills apply pipe coatings to protect the line pipe from corrosion. Often, the coating mill is located adjacent to the pipe mill, so line pipe moves directly from the pipe manufacturer to the coating facility.Coatings are a key pipe safety step.
The natural gas industry uses several different types of pipe coatings. Today a fusion bond epoxy (FBE) coating is used most widely. FBE coating can be recognized by its light blue color, often seen on pipe being transported by rail or truck. Regardless of the type of coating used, the purpose is the same: Prevent external corrosion by prohibiting moisture from coming into direct contact with the metal.
To prepare for fusion bond epoxy coating, the external surface of the pipe is thoroughly cleaned. The pipe is heated to a prescribed temperature and an epoxy powder is applied. The powder "melts" onto the heated pipe and forms a water tight barrier. Prior to transporting the pipe to the job site, the mill tests the coated pipe with high voltage electricity to evaluate the coating's insulating effectiveness.