ASME B31.3 vs API 570
ASME B31.3 and API 570 are two critical piping inspection codes used in the oil and gas industry. ASME B31.3 governs the design and construction of process piping, while API 570 covers the in-service inspection, repair, and alteration of existing piping systems. Understanding the difference is essential for QC inspectors and piping engineers.
| Criterion | ASME B31.3 | API 570 |
|---|---|---|
| Scope | Design & construction of new process piping | In-service inspection, repair & alteration |
| Phase | Construction phase (new builds) | Operational phase (existing piping) |
| Key Topics | Pipe wall thickness, stress, hydrotest pressure | Corrosion rates, inspection intervals, RBI |
| Who Uses It | Design engineers, fabrication QC inspectors | In-service inspectors, maintenance engineers |
| Inspection Focus | Welding, NDE, hydrostatic testing | Corrosion monitoring, fitness-for-service |
| Certification | ASME Section IX welder qualification | API 570 Certified Inspector |
The Verdict
If you work on new piping construction and fabrication, ASME B31.3 is your primary code. If you inspect existing piping systems in operating plants, API 570 is essential. Most senior piping inspectors hold both certifications to cover the full lifecycle.