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DNV Freespan / VIV Screening Analysis

~680 parametric cases across 3 pipe sizes and rigid jumpers
680 parametric cases analysed overnight
Generated 2026-04-15 04:03 UTC · demo_01
Live walkthrough of DNV-RP-F105 freespan VIV screening across 680 parametric cases — pipe sizes, span lengths, currents, gap ratios
Live walkthrough — DNV-RP-F105 freespan VIV screening across 680 parametric cases (3 pipe sizes × 8 spans × 5 currents × 4 gap ratios + jumper variants).

Download Capability Summary (PDF, 1 page)

Methodology

This analysis implements DNV-RP-F105 simplified VIV screening for pipeline and jumper freespans. The methodology evaluates whether vortex-induced vibrations will develop under steady current loading, using the reduced velocity parameter VR = V / (fn × D).

Screening Steps

  1. Natural frequency — beam-on-elastic-foundation model with pinned-pinned boundary conditions (conservative). fn = Cn/(2π) × √(EI / meffL4)
  2. Reduced velocity — VR = Vcurrent / (fn × D)
  3. VIV onset check — in-line onset at VR = 1.0, cross-flow onset at VR = 3.0, lock-in range 4.0–8.0
  4. Gap ratio correction — seabed proximity (e/D < 1) delays VIV onset
  5. Response amplitude — simplified A/D estimation for screening

Parameter Matrix

  • Pipelines: 8", 12", 16" × 8 spans (10–80 m) × 5 currents (0.2–1.0 m/s) × 4 gap ratios = 480 cases
  • Jumpers: 8" rigid × 8 spans (5–40 m) × 5 currents × 5 gap ratios (incl. mid-water) = 200 cases

Screening Criteria

  • PASS — no VIV expected (VR < 1.0)
  • INLINE_ONLY — in-line VIV only (1.0 ≤ VR < 3.0), typically acceptable
  • FAIL_CF — cross-flow VIV onset (VR ≥ 3.0), detailed analysis needed
  • FAIL_LOCKIN — lock-in regime (4.0 ≤ VR ≤ 8.0), critical condition

Applicable Codes & Standards

  • DNV-RP-F105 (2017) — Free Spanning Pipelines
  • DNV-RP-C205 (2010) — Environmental Conditions and Loads
  • DNV-OS-F101 (2013) — Submarine Pipeline Systems

Screening Results Summary

Pass rate includes PASS + INLINE_ONLY (acceptable for most applications).

Type Size Cases PASS INLINE_ONLY FAIL_CF FAIL_LOCKIN Acceptable %
Pipeline 8in 160 4 17 131 8 13%
Pipeline 12in 160 12 20 112 16 20%
Pipeline 16in 160 21 17 102 20 24%
Jumper 8in-jumper 200 31 35 99 35 33%

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Assumptions & Limitations

  • Pinned-pinned boundary conditions (conservative — actual supports provide partial fixity)
  • Steady uniform current perpendicular to pipe axis (worst case orientation)
  • No wave-induced loading considered (current-only screening)
  • Effective axial force = 0 (no temperature/pressure-induced axial load data)
  • Added mass coefficient Ca = 1.0 (potential flow theory)
  • Content density = 800 kg/m3 (oil-filled, conservative for empty pipe)
  • Coating thickness from pipe catalog (3LPP or FBE)
  • Thinnest available wall thickness used per pipe size (worst case for VIV)
  • No soil-pipe interaction stiffness modelled (free span only)
  • Single-mode response only (higher modes may be excited at very high V_R)
Chart 1: Natural Frequency vs Span Length
Log-scale frequency showing how longer spans reduce f_n. Jumper's thicker wall gives higher frequency at same OD.
Chart 2: VIV Onset Screening Map
Span-current screening at e/D = 1.0. Green = safe, yellow = inline only, orange/red = VIV concern.
Chart 3: Max Allowable Span Heatmap
Maximum freespan before cross-flow VIV onset at e/D = 1.0.
Chart 4: Pass/Fail Screening Matrix
Full parametric screening results for all pipeline sizes at e/D = 1.0.
Chart 5: Jumper vs Pipeline Comparison
Allowable current envelope: 8in pipeline (Sch 40) vs 8in jumper (Sch 120). Thicker jumper wall extends safe operating envelope.

These results are preliminary engineering estimates generated by automated parametric analysis. All outputs require review by a qualified engineer before use in design or operational decisions.

References: DNV-RP-F105 (2017) — Free Spanning Pipelines · DNV-RP-C205 (2010) — Environmental Conditions and Loads · DNV-OS-F101 (2013) — Submarine Pipeline Systems

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