DNV-RP-F109

Covers — on-bottom stability design of submarine pipelines: hydrodynamic wave/current loads, soil resistance, and required submerged weight (including concrete weight coating) to resist lateral displacement.

Does NOT cover (exclusions) — pipeline design basis → DNV-ST-F101; free-span VIV → DNV-RP-F105; global buckling → DNV-RP-F110.

F109 keeps the pipe in place on the seabed; the other RPs handle spanning and buckling.

F109 provides stability design methods:

• Hydrodynamic Loads — wave and current lift, drag, and inertia on the pipe.
• Soil Resistance — lateral resistance from the seabed soil.
• Stability Check — required submerged weight/weight coating for the design storm.

DNV-RP-F109 governs the on-bottom stability of submarine pipelines — ensuring a line resting on the seabed is not displaced by wave and current forces. It balances hydrodynamic lift, drag, and inertia against the pipe's submerged weight (commonly boosted by a concrete weight coating) and the lateral resistance of the seabed soil, for the design storm condition.

Inadequate stability leads to lateral sweeping, new free spans, and fatigue. F109 works alongside DNV-ST-F101 and the free-span (F105) and buckling (F110) RPs.

Engineering Note: Stability, spanning, and buckling are coupled — a pipe that moves laterally (F109) can create new free spans (F105); design them together rather than in isolation, especially in shallow, high-current environments.