Abstract: A new coating-spraying technique, high-pressure air-free spraying technique, has been developed and tested in the light of the serious corrosion and scale deposit existed in the sour natural gas and brine pipeline. The result shows that the polyurethane modified epoxy primer (finish painting)has perfect performence in water resistance, strong acid and/or base resistance, sulphide resistance and atmospheric corrosion resistance. The painting process, principle of high-pressure air-free spraying and field coating repair are introduced, and the technical-economic evaluation has been made between the new method and typical method, some suggestions have been proposed.