Corrosion protection is not only limited to the external surface of the pipes. In cases that the fluid inside the pipeline is corrosive or contains suspended materials, it can cause corrosion inside the pipe. Hence, protection of the internal surface of the pipes is of great importance.
Importance of the Internal Coatings of Pipes
Experience has shown that the no. of pigging for the pipes with internal coating is much less than the required times for the pipelines without coating. Movement of PIG on the inside surface of the pipes with internal coating is much easier than the steel pipes without the coating, and hence, the pigging action is done faster inside the pipelines. This factor can make for the costs for applying the internal coating. Experience has shown that using internal coating can reduce the maintenance costs of the valves, considerably. Excavation, changing, and innovating the surface asphalt of streets are indicating the costs for erosion and wearing out of underground pipelines. These costs are much more than the costs for applying the internal coating. The safety/protection factor that is provided is not simply quantifiable, and it would be better to observe the internal coating as an insurance deciding policy.