What is the recommended interval for a close interval survey of buried pipe with poor CP?

What is the recommended interval for a close interval survey of buried pipe with poor CP?

• A. 5 years
• B. 3 years
• C. 7 years
• D. 10 years

Answer: (A)

Close-interval surveys check the polarization potential along a buried pipeline to verify that cathodic protection is giving adequate protection. When CP is poor, the risk of under-protection and corrosion is higher, so regular monitoring is essential. The typical practice is to perform a close-interval survey every five years. This interval strikes a practical balance between catching changes in CP or coating condition and the costs of surveying. If a survey shows under-protection or significant coating damage, or if CP conditions change, the interval should be shortened (often to about three years or less) until the CP system is corrected. Longer intervals (seven or ten years) would risk missing deterioration in a system with poor CP.

Close-interval surveys check the polarization potential along a buried pipeline to verify that cathodic protection is giving adequate protection. When CP is poor, the risk of under-protection and corrosion is higher, so regular monitoring is essential. The typical practice is to perform a close-interval survey every five years. This interval strikes a practical balance between catching changes in CP or coating condition and the costs of surveying. If a survey shows under-protection or significant coating damage, or if CP conditions change, the interval should be shortened (often to about three years or less) until the CP system is corrected. Longer intervals (seven or ten years) would risk missing deterioration in a system with poor CP.