What is the maximum thickness inspection interval for Class 2 & 3 piping?

What is the maximum thickness inspection interval for Class 2 & 3 piping?

• A. The lesser of 10 years or half life of the pipe.
• B. The greater of 5 years or the pipe's full life.
• C. Exactly 10 years for all pipes.
• D. The lesser of 15 years or full pipe life.

Answer: (A)

In this topic, the time between thickness checks is limited to keep thinning from slipping past allowable limits. For Class 2 and 3 piping, the maximum inspection interval is the smaller of 10 years or half the remaining service life of the pipe, based on the predicted corrosion rate. This means you first estimate how long the pipe can continue thinning before it reaches its minimum required thickness, using current thickness, minimum thickness, and the corrosion rate. Call that remaining life. Then you take half of that remaining life and compare it to 10 years; the smaller value is the interval you should use. Why this works well: it ensures inspections are frequent enough to detect significant thinning before a failure risk grows, but it also avoids unnecessary frequent checks when thinning is slow. If the remaining life is short, you’ll inspect more often; if thinning is slow, you cap the interval at 10 years. Not fitting options would rely on fixed, longer intervals or ignore the corrosion rate. For example, choosing a fixed 10-year interval for all cases is too arbitrary, and phrases like the complete pipe life or a larger, fixed number don’t reflect how actual thinning progresses.

In this topic, the time between thickness checks is limited to keep thinning from slipping past allowable limits. For Class 2 and 3 piping, the maximum inspection interval is the smaller of 10 years or half the remaining service life of the pipe, based on the predicted corrosion rate. This means you first estimate how long the pipe can continue thinning before it reaches its minimum required thickness, using current thickness, minimum thickness, and the corrosion rate. Call that remaining life. Then you take half of that remaining life and compare it to 10 years; the smaller value is the interval you should use.

Why this works well: it ensures inspections are frequent enough to detect significant thinning before a failure risk grows, but it also avoids unnecessary frequent checks when thinning is slow. If the remaining life is short, you’ll inspect more often; if thinning is slow, you cap the interval at 10 years.

Not fitting options would rely on fixed, longer intervals or ignore the corrosion rate. For example, choosing a fixed 10-year interval for all cases is too arbitrary, and phrases like the complete pipe life or a larger, fixed number don’t reflect how actual thinning progresses.