What are examples of coating defects in pipelines?

Coating defects in pipelines specifically refer to irregularities or flaws in the protective layer that shields the pipe from environmental damage, corrosion, and other forms of degradation. The presence of holidays and blisters directly indicates issues with the coating application or integrity.

Holidays are areas where the coating is missing or has failed, exposing the underlying metal to potential corrosion, while blisters are formed when moisture or gases get trapped between the coating and the surface of the pipe, creating bubbles. Both of these defects can compromise the performance and lifespan of the pipeline system.

The other options describe issues related to the structural integrity or visibility of the pipe rather than specific defects of the coating itself. Leaks and ruptures pertain to failures in the actual pipe material, while fading and discoloration are more about the aesthetics of the coating rather than its protective capability. Cracks and fractures similarly refer to physical breaks in the pipe material rather than the coating. Therefore, holidays and blisters represent clear examples of coating defects that can lead to serious operational and maintenance concerns in pipeline systems.