DNV-RP-F101 isolated metal-loss pressure screening

DnvRpF101CorrodedPipelineScreeningKernel provides a narrow deterministic calculation for the current DNV-RP-F101 2019-09+AMD:2025-09 basis: one isolated longitudinal metal-loss defect under internal pressure. The result is always a SCREENING result requiring engineering review. It is not a fitness-for-service decision and does not reproduce licensed safety-factor tables.

DNV identifies the current edition and a broader scope covering internal pressure, internal pressure combined with longitudinal compressive stress, and multiple assessment approaches on its DNV-RP-F101 publisher page. Use the purchased standard and project assessment procedure to establish defect classification, input values, factors, interactions, load cases, and acceptance.

Implemented equation

For steel outside diameter $D$, externally established assessment wall thickness $t$, axial defect length $l$, assessment defect depth $d$, and characteristic ultimate tensile strength $UTS$, the kernel evaluates the public isolated-defect equation:

\[Q=\sqrt{1+0.31\left(\frac{l}{\sqrt{Dt}}\right)^2}\] \[P_f=\frac{2t\,UTS}{D-t}\left(\frac{1-d/t}{1-(d/t)/Q}\right).\]

The assessment depth is measured maximum defect depth plus a caller-controlled depth allowance. The assessed pressure is internal absolute pressure minus external absolute pressure. NeqSim also reports a caller-controlled pressure limit $P_{limit}=f_pP_f$, utilization $U=(P_i-P_e)/P_{limit}$, and margin $P_{limit}-(P_i-P_e)$.

The multiplier $f_p$ is deliberately an input. NeqSim does not infer DNV safety class, inspection accuracy, partial factors, assessment approach, or project acceptance from open-source defaults.

Runnable Java example

StandardEdition edition = StandardEdition.defaultEdition(StandardType.DNV_RP_F101);
DnvRpF101CorrodedPipelineScreeningKernel.Input input =
    DnvRpF101CorrodedPipelineScreeningKernel.Input
        .builder(edition, "Pipeline")
        .steelOuterDiameterM(0.508)
        .assessmentWallThicknessM(0.0127)
        .measuredDefectDepthM(0.004)
        .defectDepthAllowanceM(0.0005)
        .defectAxialLengthM(0.2)
        .characteristicUltimateTensileStrengthPa(535.0e6)
        .internalPressurePaAbsolute(10.1e6)
        .externalPressurePaAbsolute(0.1e6)
        .callerControlledPressureFactor(0.72)
        .geometryVerified(true)
        .inspectionSizingVerified(true)
        .materialStrengthVerified(true)
        .pressureBasisVerified(true)
        .projectFactorVerified(true)
        .isolatedLongitudinalMetalLossApplicabilityVerified(true)
        .build();

EngineeringCalculationResult<DnvRpF101CorrodedPipelineAssessment> result =
    new DnvRpF101CorrodedPipelineScreeningKernel().calculate(input, null);
DnvRpF101CorrodedPipelineAssessment assessment = result.getValue();
Map<String, Object> report = assessment.toMap();

For these demonstration inputs, assessment depth is 4.5 mm, calculated failure pressure is about 22.3466 MPa, the caller-controlled limit is about 16.0896 MPa, and pressure utilization is about 0.62152. These values are deterministic regression data, not an independent DNV benchmark or an acceptance recommendation.

The executed notebook uses the same API, shows defect-depth and length sensitivity, and demonstrates a blocked input when inspection evidence is not verified.

Fail-closed evidence boundary

Calculation is blocked unless all of the following are explicit and internally valid:

• exact unamended 2019-09+AMD:2025-09 edition and catalogued pipeline/riser applicability;
• positive outside diameter, assessment wall thickness, axial defect length, and characteristic ultimate tensile strength;
• positive measured defect depth, non-negative caller-controlled allowance, and positive remaining wall thickness;
• positive internal and external absolute pressures with internal pressure above external pressure;
• a caller-controlled pressure factor above zero and no greater than one; and
• external verification of geometry, inspection sizing and allowance, material strength, pressure basis, project factor, and isolated longitudinal metal-loss/internal-pressure applicability.

The verification flags are attestations. The inspection reports, uncertainty/growth basis, material records, pressure cases, licensed factor source, and accountable approvals remain external evidence.

Not implemented

The kernel does not calculate or approve:

• multiple, interacting, or complex-profile defects;
• combined internal pressure and longitudinal compression or other combined loads;
• probabilistic assessment, inspection-accuracy models, or partial-factor selection;
• corrosion-growth prediction or conversion of a corrosion rate into defect dimensions;
• crack-like flaws, gouges, dents, blisters, weld flaws, laminations, or material degradation;
• repair selection, inspection interval, fitness-for-service acceptance, or certification; or
• detailed finite-element or fracture-mechanics assessment.

NorsokM506CorrosionDesignKernel predicts a simplified CO2 corrosion rate and projected uniform wall loss. That rate/allowance workflow is not an RP-F101 defect assessment and must not be silently converted into measured defect geometry.

Separation from DNV-ST-F101

DNV-RP-F101 assessment of existing metal loss is separate from original pipeline-system design. This kernel does not replace DNV-ST-F101 pressure containment, collapse, propagation buckling, local buckling, load interaction, fatigue, incidental/test pressure, de-rating, safety class, ovality, fabrication route, or installation-strain checks. Those design checks and their load-case evidence remain independently required.