DNV RP-C203 (2016)

DNV RP-C203 (2016) provides a comprehensive fatigue assessment framework for offshore steel structures, relying on hot spot stress calculations and directional SN curve classification. SDC Verifier implements the standard per the 2016 revision, using Method B (Chapter 4.3.4) for stress extraction and applying environment-specific corrections from Chapters 2.4.4 (air) and 2.4.5 (seawater with cathodic protection).

Fatigue Check Setup:

• Environment Type: Set globally or by selection (air or seawater with CP)
• Stress Method: Method B — 0.5t offset from weld toe or intersection line
• SN Curve Assignment:
  • Non-welded: single curve per direction
  • Welded: directional classification (X = parallel, Y = perpendicular)
  • Weld Intersections: use lowest curve class between X and Y

Stress Recalculation Principal stress angles and Table F-1 are used to automatically interpolate fatigue class ranges between SN curves (e.g., F to D) based on weld orientation.

Thickness Factor Applied for welded elements using a reference thickness (typically 25 mm), and exponent values from Tables 2-1 to 2-4. Can be overridden per element.

Other Features:

• Hot spot stress factor (1.12) applied by default unless disabled
• Optional use of user-defined SN curves (C2*)
• Supports fatigue assessment of C-Mn steels with yield strength < 960 MPa

This standard is essential for fatigue-sensitive offshore equipment including jacket structures, subsea components, and topside support frames.