What visual defect might indicate a problem with a coating on a gas pipe?

Blisters on a gas pipe coating are a significant visual defect that can indicate an issue with the integrity of the coating. When the protective coating is compromised, moisture or other contaminants can become trapped beneath the surface. As the underlying substrate (usually metal) begins to corrode or oxidize, gases are generated that can cause the coating to lift. This lifting results in blistering, which not only impacts the aesthetics but also exposes the pipe to further corrosion, potentially leading to dangerous leaks in a gas piping system.

Identifying blisters is crucial during routine inspections because they signal the need for immediate attention to prevent further deterioration of the pipework. Addressing blistering early can help maintain the safety and reliability of the gas distribution system.