However, an inspection system is only as reliable as its validation. This is where comes into play. Titled Pipe girth weld automated ultrasonic testing system qualification and project specific procedure validation , this Recommended Practice (RP) published by Det Norske Veritas (DNV) provides the definitive global framework for verifying that an AUT system can accurately detect and size weld defects. Why DNV-RP-F118 Matters
| Standard | Focus | Key difference | |----------|-------|------------------| | | Integrated riser system on floating units | Most rigorous for fatigue and accidental loads; explicit treatment of FLS and ALS; preferred by European and Asian operators. | | API RP 2RD | Design of risers for floating productions | More prescriptive, less probabilistic; widely used in US Gulf of Mexico but recognizes F118 for fatigue. | | ISO 13628-7 | Completion/workover risers | Narrower scope (intervention risers, not production risers). | | DNVGL-ST-F201 | Dynamic risers (general) | A standard (higher safety level) than RP; F118 is often the companion guide to ST-F201 for floating unit interfaces. |
A core component of the qualification process involves rigorous statistical analysis. During qualification, the AUT system is used to scan welds that contain real, known flaws. The system's estimates of flaw size and location are then compared to actual measurements obtained by sectioning the weld and examining it under a microscope. dnv-rp-f118
The official standard can be purchased in secure PDF or printed format from authorized distributors like Accuris (formerly Techstreet), with a standard price of around . It is also available through other commercial standards platforms.
DNV-RP-F118 is known for its strict statistical thresholds to ensure high confidence in the data: PoD Criterion: However, an inspection system is only as reliable
: Analysis of existing detection and sizing accuracy data.
The qualification framework outlined in DNV-RP-F118 is rigorous and split into systematically structured stages: 1. Document and System Review Why DNV-RP-F118 Matters | Standard | Focus |
Because physical qualification is time-consuming and expensive, industry professionals often use simulation tools like CIVA NDT Software to augment the process. Simulation can: Predict probe coverage and beam behavior. Help design calibration blocks.
It also recommends (strain gauges, accelerometers) for risers in regions with high current or iceberg risk.
The standard operating classification for production pipelines.