What is the maximum external inspection interval for Class 3 piping?

What is the maximum external inspection interval for Class 3 piping?

• A. 8 years
• B. 12 years
• C. 15 years
• D. 10 years

Answer: (D)

The main idea here is how often you should schedule external inspections based on the pipe class. API 570 uses a risk-based framework that assigns longer intervals to lower-risk classes. For Class 3 piping, the upper limit for external inspections is 10 years. This reflects that Class 3 piping is considered less critical than Class 1 or 2, so the external inspection interval can be longer, provided there are no other factors driving a shorter schedule (like prior corrosion, coating damage, harsh service, or elevated corrosion rates). In practice, if everything is in normal condition, you would not exceed a 10-year external inspection interval for Class 3. If any adverse conditions are present, the interval should be shortened accordingly.

The main idea here is how often you should schedule external inspections based on the pipe class. API 570 uses a risk-based framework that assigns longer intervals to lower-risk classes. For Class 3 piping, the upper limit for external inspections is 10 years. This reflects that Class 3 piping is considered less critical than Class 1 or 2, so the external inspection interval can be longer, provided there are no other factors driving a shorter schedule (like prior corrosion, coating damage, harsh service, or elevated corrosion rates). In practice, if everything is in normal condition, you would not exceed a 10-year external inspection interval for Class 3. If any adverse conditions are present, the interval should be shortened accordingly.