How can we protect the insides of natural gas pipelines against corrosion ?
Here, coating compositions based on coal tar/epoxy resins, epoxy and phenolic resins have proved effective. The last named are only suitable for stoving finishes, i.e. they cannot be used on site. It is important to remove all traces of rust from surface, which can best be achieved by mechanical scrapers, rotating wire brushes and in special cases, by pickling in acids.
The number of coates to be applied will depend on the condition of the surface, but two or three coats are normally sufficient. The total film thickness is usually around 250 ym.
Solvent free paints should be given preference in order to avoid the possibility of evaporation problems. Powdered paint, based on epoxy and epoxy ester resins and applied mechanically are gaining increasing importance.