chapter 5 pipelines, risers and subsea systems og... · pipelines, risers and subsea systems. 2...

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CHAPTER 5CHAPTER 5Pipelines, risers and subsea systemsPipelines, risers and subsea systems

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REVIEWED DOCUMENTSREVIEWED DOCUMENTSPipelinesPipelines

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For pipelinesFor pipelinesISO (25.03.2008ISO (25.03.2008

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STEP 0 Define system level to

be analyzed

STEP 1 Collection of information

STEP 2 Today status evaluation

Accepted?

STEP 3

1. Information collection for future operation

2. RISK assessment

STEP 4 Mitigation plan

STEP 5 Implementation

Yes

Yes

No

No

STOP

Yes Repair/

upgrade?

No

Accepted?

Repair/ upgrade?

No

Yes

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DNV PROPOSED PIMDNV PROPOSED PIMPipelinesPipelines

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REVIEWED DOCUMENTSREVIEWED DOCUMENTSFlexible pipesFlexible pipes

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REVIEWED DOCUMENTSREVIEWED DOCUMENTSSubsea Production SystemsSubsea Production Systems

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IMPORTANT INFORMATIONIMPORTANT INFORMATIONSubsea SystemsSubsea Systems

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IMPORTANT INFORMATIONIMPORTANT INFORMATIONSubsea SystemsSubsea Systems, cont., cont.

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LIFE EXTENSION ASSESSMENTLIFE EXTENSION ASSESSMENTStep 1 Step 1 –– Collection of informationCollection of information

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IMPORTANT INFORMATIONIMPORTANT INFORMATIONStep 1 Step 1 -- ExamplesExamples

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POSSIBLE DEGRADATION MECHANISMSPOSSIBLE DEGRADATION MECHANISMSSubsea systemsSubsea systems

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STEP 2STEP 2Possible degradation mechanismsPossible degradation mechanisms

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STEP 2STEP 2Today statusToday status

STEP 3STEP 3Risk AssessmentRisk Assessment

STEP 0 Define system level to

be analyzed

STEP 1 Collection of information

STEP 2 Today status evaluation

Accepted?

STEP 3

1. Information collection for future operation

2. RISK assessment

STEP 4 Mitigation plan

STEP 5 Implementation

Yes

Yes

No

No

STOP

Yes Repair/

upgrade?

No

Accepted?

Repair/ upgrade?

No

Yes

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STEP 4STEP 4Mitigation Mitigation –– Actual methodsActual methods

Upgraden Repair and/or replacement of components or complete piping

Monitoringn Monitoring process and operation parameters is an important

mitigation action for the pipeline, riser and subsea system. ­ Pressure­ Temperature­ Content of solids (sand)­ Fluid composition (inclusive water content)­ Stress, strain, movement

n For rotating equipment: vibration analysis n Corrosion monitoring n Sand detection and/or erosion monitoring

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STEP 4STEP 4Mitigation Mitigation –– Actual methodsActual methods, cont., cont.

Inspectionn The inspection program for subsea pipelines and flowlines is often

based on a RBI analysis. For internal inspection intelligent pig is most frequently used.

n Visual inspection with diver or video/camera is often used for external inspection.

Maintenancen The output from the LE analysis can also be an update of the

maintenance program.Testingn Pressure testing can be used to verify that the systems fulfill the

defined pressure requirement. Pressure testing is frequently used to control the integrity of the flexible pipes. Testing is also used to control the functionality of valves (e.g. safety valves).

New barriersn Most likely not applicable

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LACK OF KNOWLEDGELACK OF KNOWLEDGESubsea systems Subsea systems –– selected areasselected areas

n Subsea production systems­ Structural integrity monitoring system­ Sand disposal system

n Methods for subsea inspection ­ Structures­ Pipelines­ Flexible pipes

n Reliable corrosion monitoring system for installed pipelinesn Hydrogen Induced Stress Cracking­ Bolting material ­ Flowlines/pipelines­ High strength materials

n Modeling of material degradation and remaining life