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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