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7/16/2019 D05 Leif_DNV_Changes in DNV-OS-F101 2012.pdf
DNV Pipeline Codes / Offshore Standard DNV-OS-F101
GLOBAL PIPELINE AWARD
2009 WINNER
DNV Rules for Submarine Pipeline Systems, 1976- The first complete pipeline code for offshore pipelines
- Based on allowable stress format.
DNV Rules for Submarine Pipeline Systems, 1981- Update of 1976 version and became a wide spread code
DNV Rules for Submarine Pipeline Systems, 1996- A completely new version, incorporating the limit state format with calibrated safetyfactors based on the SUPERB J IP work
DNV-OS-F101:2000- Converted to pure technical standard
DNV-OS-F101:2007- General Improvement
- Aligned with ISO3183 Linepipe standard
Global Pipeline Award 2009
DNV-OS-F101:2012- General Improvement
- Aligned with ISO 3183
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Proposed text sent sent to parties commenting on subject in the hearing for review:
- Assemblies, in-line: Components such as valves, flanges, tee’s, wye’s, PLEM, or PLETwhich are integrated part of the pipeline and installed welded to the pipeline.
- Assemblies, pipeline: Risers, pipe strings (for reeling or towing), spools which are weldedonshore.
First party proposed the following modifications:- Assemblies, in-line: Pipeline components such as valves, flanges, tee’s, wye’s, PLEM, or
PLET which are integrated part of the pipeline and connected to the pipeline during pipelineinstallation.
Second party proposed further that collars, reducers, transition pieces etc should beadded to in-line assemblies definition
Third party then proposed the following
- Assemblies, in-line: Assemblies of linepipe sections and pipeline components (see Table 1-1and Sec.1 C288) which are integrated part of the pipeline, and installed simultaneously withthe pipeline during pipeline installation.
- Sec.1 C288: Pipeline Components: Any items which are integral parts of the pipeline systemsuch as flanges, tees, bends, reducers and valves.
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- 301 A systematic review shall be carried out at all phases to identify and evaluate threats,the consequences of single failures and series of failures in the pipeline system, such that
necessary remedial measures can be taken. The extent of the review or analysis shall reflectthe criticality of the pipeline system, the criticality of a planned operation, and previousexperience with similar systems or operations. The uncertainty in the applied risk reviewmodel itself shall also be qualified.
301 The overall requirement to systematic reviewin Sec.2 shall be reflected in the offshoreconstruction of the pipeline.
302 Systematic analyses of equipment andoffshore construction shall be performed inorder to identify possible critical items or
activities which could cause or aggravate ahazardous condition, and to ensure thateffective remedial measures are taken.
303 The extent of systematic review shall dependon criticality of operations and experience fromprevious similar operations.
304 The systematic analyses should be carried outas a failure mode effect analysis (FMEA) forequipment and hazard and operability studies(HAZOP) for critical operations. Recommendedpractice for FMEA and HAZOP is given in DNV-RP-H101. For HAZOP, reference is also madeto API RP 17N.
Guidance note:
- Typical items to be covered for HAZOP include:
- simultaneous operations
- lifting operations including pipe jointtransportation and storage
- dry and wet buckles including flooding of pipe
- initiation and lay down including shore pull- operations inside safety zones
- critical operations (laying in short radii curves,areas with steep slopes etc.)
- failure of equipment and measuring andmonitoring devices
- tie-in operation
- pre-commissioning activities
- environmental conditions and weather criteria
- emergency abandonment
- loss of station keeping capabilities
- survey.
- It is desired to mitigate potential hazards byengineering measures.
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The incidental pressure is defined as having a probability less than 10-2 of beingexceeded during a year
If the pressure probability density function does not have a monotonic decay beyond10-2 the pressure exceeding the incidental pressure shall be checked as accidentalloads in compliance with Sec.5 D1000
The submarine pipeline system shall have a specified incidental pressure or be splitinto different sections with different specified incidental pressures. These should all
be defined at a defined reference elevation
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The purpose of the Pipeline Safety System is to protect the submarine pipelinesystem by limiting the operating parameters within the parameter safety envelopeduring incidental operation
- E.g. to ensure that the local incidental pressure is not exceeded at any point in the pipelinesystem in the event of failure of the pipeline control system.
The Pipeline Safety Systemshall operate automatically.
Due account shall be given to the tolerances of the pipeline safety system
The Pipeline Safety shall comply with the requirements of IEC 61511.
Pipeline Safety Systems required with a probability of failure on demand of less than10-3 shall consist of two independent systems.
The pressure containment capacity of the pipeline system is ensured by:
- Design criteria and safety factors
- Pressure testing all pressure containing parts by
- Strength pressure test; Mill pressure test for pipe joints and hydrostatic test for components (Sec.8G100), and
- Gross error leak test; System pressure test and hydrostatic test for pipeline assemblies
Unless waived by B204 or Sec.7 E107.
- Section 5 B201
Components specification
- A specification reflecting the results of the materials selection according to thissection and the pressure test philosophy in Sec.5 B200 and referring to Sec.8,shall be prepared by the Purchaser
- Section 6 C301
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- Rephrasing and clarifications to make requirements more clear, e.g. for dimensionalmeasurements and tolerances
Changes (highlights) to MPS/MPQT:
- Each MPQT shall include one pipe from two different test units of different heats
- For C-Mn steels with SMYS > 450 MPa, the qualification of the MPS should be completedprior to start of production
- Included essential variables to the longitudinal weld seam with regard to MPS (changes towelding wire type/thickness/configuration, flux, shielding gas, welding equipment). In caseissues only related to the welding process have been changed, the re-qualification of theMPS may be limited to the weld only (e.g. not base material testing).
- In case issues only related to the welding process have been changed, the re-qualification of the MPS may be limited to the weld only (e.g. not base material testing).
- In the specific case of failed fusion line CVN tests, retesting of further 2 sets removed fromthe failed MPQ pipe (at the same position relative to the wall thickness) is permitted prior todeclaring the MPQT as having failed.
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Sect. 8 – Construction-Components and Pipeline Assemblies
In general, the update includes:
- Rephrasing and clarifications to make requirements more clear, e.g. acceptance criteria totesting requirements
- Update to reflect new revision of ISO 15590-1 (bends)
- Requirements to bolting materials included in Section 8
Changes (highlights):- Maximum hot forming temperature increased to 1100°C with opening to increase to 1150°C
if microalloying elements to prevent grain growth are added.
- Pressure testing with covered welds accepted. Modified requirements to pressure testingwith and without coating, e.g. hold time when acceptance is based on pressure observation.
- Sub.sec. F partly re-written and re-structured, e.g. requirements to storage andtransportation added
An invitation to a J IP with focus on Section 8 is under development. Some of thecomments to Section 8 will be handled during this J IP, e.g. a possible re-
construction of the subsections and major changes to materials and testing.
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Section completely revised on hearing version compared to 2007
Highlighted that production testing is also relevant for pipe strings for reeling.Production testing requirement moved to App. C (applicable to both Sec. 10 andSec. 8).
Various comments (as normally) to buckle detection requirement. Requirement toHAZOPD/HAZID which should found basis for buckle detection. Requirement tobuckle detection changed from ‘shall’ to ‘should’.
Requirement to sorting of pipes in the pipe string removed. GN included in Sec.5that if assumed by design.
Several comments to related to change from 95% to 97% ID for gauge plates.Changed back to 95% as in 2007-version.
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Reference stress shall be calculated in accordance with the plate solution specifiedin BS 7910 (not the Kastner solution)
- This will increase the crack driving force for surface flaws (more critical)
- More correct based on comparison with 3D FE fracture mechanics analyses
Plastic collapse limit (Lr cut-off)c hanged, true UTS divided by true YS for strain-based loading
- The Lr cut-off will increase, failure point will not be plastic collapse, but tearing instability orfracture toughness controlled
- Weld residual stress may be somewhat more relaxed
- For high strain situations, this will typically give larger allowable flaw sizes
How to define “upper-bound” and “lower-bound” stress-strain curves clarified (basedon statistics and amount of testing)
How to define weld over-match clarified (based on statistics and amount of testing)
Not necessary to combine installation load with all possible fatigue and operationalload cases (less conservative). Simple probabilistic-based rules introduced
New Subsection giving some guidance on FE fracture mechanics analyses
Subsection C deleted “Generic ECA for strain below 0.4%” (replaced by new AUTworkmanship criteria in Appendix D)
No safety factor on fatigue life required for fatigue crack growth analyses
Number of comments received: approx. 100 (several are the same)
- Accepted/implemented: 6
- Partially accepted/implemented:41
- Not accepted/no changes:32*
- Printing errors (implemented/corrected): 18
*Quite many comments are not directly a proposal for change, butclarification/question to Appendix A. Hence, these are in general not implemented butsome more clarifications are added.
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- Rephrasing and clarifications to make requirements more clear, e.g. for dimensionalmeasurements and tolerances
Changes (highlights) to Welder Qualification and Welding Consumables:
- Repair welders will be qualified for all types of repair after successfully being tested on fullpenetration repair providing the welding processes are the same for the particular section
- For weld filler metal the following has been included (requirements to the weld metal strengthwas contradictory and not clear in 2007-edition):
- For welds exposed to strainİl, nom 0.4%: the weld metal yield strength measured during weldingqualification shall not be more than 20 MPa below the specified maximum yield strength of the basematerial
- For welds exposed to strainİl, nom <0.4%: the yield stress (Rt0.5) of the weld metal should be minimum80 MPa above SMYS of the base material
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- The maximum heat input variation for a pWPS is increased from 30% to 40% and must bebased on two qualified procedures with a 20% difference in heat input allowing a ±10%
tolerance for each procedure.- The change of steel supplier is not an essential variable for components.
- More clarifications with regards to how to carry out qualification welding is given, e.g. how torecord heat input
Changes (highlights) to Examination and Testing for WPQ:
- Delayed NDT of test pieces reduced from 48 hours to 24 hours
- For longitudinal and girth welds exposed to strain İl, nom 0.4%, the fracture shall not belocated in the weld metal, while for longitudinal and girth welds exposed to strainİl, nom < 0.4%, the fracture should not be located in the weld metal.
Changes (highlights) to Material and Process Specific Requirements:
- Maximum interpass temperature for welding on CRA’s is increased from 100°C to 150°C
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Main issues commented on and adjustments due to external hearing:
- The updated requirements of minimum 1000 lx viewing conditions for visual and liquidpenetrant inspections will be kept. DNV-OS-F101 will then comply with all standards
regarding viewing conditions.- The proposed Table D7, acceptance criteria for AUT, has been rewritten to improve clarity
and moved to Appendix E.
- H410: The paragraph has been rewritten due to comments on the new requirement of detection of a reference indicator on pipe ends by all probes. The revised text specifiesreflector and opens up for agreement on alternative reflectors if the specified reflector isfound unsuitable.
- A500/A504: Change in this paragraph was interpreted as it will become unacceptable to uselevel 1 operators. The paragraph will be rewritten to better specify the intention, that criticaltasks for the inspection as calibration, data acquisition and interpretation of the results shallinclude personnel qualified to at least level 2.
Main issues commented on and adjustments due to external hearing:
- The scope of a full qualification will remain as according to DNV-RP-F118.
- Added clear guideline on AUT validation in a new subsection, as requested by severalcompanies. AUT validation requirements will be based on DNV-RP-F118, with opening for alimited scope (min. 12 defects) for applications involving <0.4% accumulated strain.
- Subsection E: Workmanship style acceptance criteria for AUT, applicable when the
accumulated strain is <0.4%, is added. This table has been moved from Appendix D, andwas commented on by several companies.
- B502: The requirement of having a weld in the calibration block for inspection of CRAmaterials has been abandoned.
- B413: A wider range of over trace in adjacent fill channels will be allowed, in order to betterreflect the actual inspection situation. The range has been adjusted from between 6 dB -10dB to between 5%-40% FSH when reference is set at 80% FSH.
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