iafmi – technical sharing session presented by andi palkar

IAFMI – Technical Sharing SessionPresented by Andi Palkar – August 2016

Linepipe Manufacturing Process – Spiral/Helical


International Standard and Specification used for linepipe manufacturing references:

• API Spec 5L 44th edition, Specification for Linepipe• ISO 3138, Specification for Linepipe• DNV OS F101, Submarine Pipeline System

The above standards regulate aspects of linepipe manufacturing such as prosesmanufacturing and material, material requirements, inspection, and testing for seamless,HFI-ERW LSAW (UOE), and also Helical/Spiral Pipe.

INDUSTRY CODE & STANDARD



Fabrication factor for spiral/helicalpipe is not specifically defined,however, in term of forming and heattreatment condition 0.85 used incalculation hence the required wallthickness resulted from propagatingassessment will be similar withSAWL/UOE pipe.


MANUFACTURER – Spiral Pipe in Indonesia

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KHI BKSI SPINDO INDAL BPI SEAPI

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Spiral Pipe Manufacturing Capacity in Indonesia

Non Spiral PipeSpiral pipe


Engineering Design:

Similar method for wall thickness calculation between Spiral andLSAW.

Linepipe Manufacturing:

Poor dimensional control in the mill leads to fit up problems on site

absence of mechanical expansion after forming, lead to pipe withovality and poor dimensional characteristics

Due to coils lack cold expansion consequently effect of higherunrelieved residual stress : affect the fracture propagation

Linepipe Coating Contractor:

Poor weld bead profile cause 'tenting' and early coating breakdownfrom entrapped or diffused moisture under the coating; worst withtape coatings or coatings applied as film such as polyethylene

Pipelay Contractor:

disturb field welding process on the pipelay barge especially forapplication of Automatic Welding Machine.

Impact of dynamic loading and fatigue has not been researched:Local strength within sagbend/overbend, and on the roller support

Operation – Intelligent Pigging:

excessive weld beads may cause lift-off of the probe, resulting inan error reading or masking of the defect signal.

Technical Aspect – Concerns from Industry


Spiral Pipe DNV JIP – Phase1The scope of DNV JIP Phase-1 is the state-of-the-art review :- literature research,- international codes& standards,- DNV & MSCKenny In house experience,- partner’s experience and contributions.

DNV Phase-1 Result:

Although it has been applied in some cases and Materialand weld properties seem to meet recognized offshorestandards, Offshore use of spiral welded pipe is not commonpractice, due to the following basis:

No design code fully covers the use of spiral weldedpipe for offshore applications without project-specificstudies.

Different design and installation issues should be furtherclarified in order to conclude the use of spiral for offshoreapplication.


Spiral Pipe DNV JIP Phase2 A technology assessment is the basis for Phase 2

- FE analysis to establish the behavior of spiral weldedpipe in critical situations during installation andoperation

- Full scale bend test of spiral welded pipe to calibratethe FE analysis. This also included quite extensivecharacterization of the linepipe used for the full scaletests.

- Review of the DNV-OS-F101 design criteria to assesswhether they can be applied for spiral welded pipe.

- Development of a guideline for use of spiral weldedpipe for offshore applications

Project Guideline


Spiral Pipe DNV JIP Phase2


FE Modeling Configurations:

The finite element models are controlled thedisplacement at the load application points isspecified

For the 4-pt bending, the distance between the loadpoints is 3 m.

For 3pt and 4 pt configuration, the distance betweenthe supports is 15 m

Mo del of 3-pt Bending Test o f UOE Pipe

Shell elements (mainly for the pipe coil) and solid elements(mainly the spiral weld and a limited width of attachedplate).

Post Processing FE analysis result:

compared with results of full-scale tests, in order tovalidate FEA as a reliable method for predicting theresponse of spiral pipes

Compare with existing prediction in DNV OS F101code

DNV JIP Phase 2– FE ANALYSIS

3pt model the pipeline within overbend on stinger

4pt model the pipeline within sagbend


DNV JIP Phase 2– FEA FE ANALYSIS 3 Points IAFMI – Technical Sharing Session

Presented by Andi Palkar – August 2016

DNV JIP Phase 2– FEA FE ANALYSIS 4 PointsIAFMI – Technical Sharing Session


DNV JIP Phase 2– FULL SCALE TEST- 3 Points


DNV JIP Phase 2– FEA & FULL SCALE TEST Comparison - 3 Points


DNV JIP Phase 2– FULL SCALE TEST- 4 Points


DNV JIP Phase 2– FEA & FULL SCALE TEST Comparison - 4 Points


Spiral Pipe DNV JIP Phase 2 Result – Engineering Design

Local Buckling (External Overpressure system collapse) during installation (as laid pipeline):• assessment depending on maximum Project water depth as the data use in DNV JIP is not relevant with each specific project.• The absence of the assessment will be a risk of pipeline buckle and collapse during operation life.

Running Fracture Assessment is required for High Pressure Gas Pipeline• The absence of the assessment will be a risk of pipeline leak during operation life

Sour Service effect of residual stress as SAWH is not mechanically expanded• The absence of the assessment will be a risk of pipeline leak and rupture during operation life

Fatigue due to cyclic load at spiral weld as well as girth weld related to pipeline free span (VIV), riser (VIV), Pipeline withlarge/frequent variation in pressure and temperature• Pipeline oscillation and reaching fatigue cycle will be a risk of pipeline collapse during operation life

• However there are some limitations that very important subjects have not been covered in DNV OS F101 for SpiralPipe (SAWH) and project specific assessment is required. The limitations are as follows:

• Testing and FE analysis result the structural behavior of the spiral welded linepipe and UOE pipe are comparablefor typical loading condition following DNV OS F101.

• The project specific assessment (FE Analysis and full scale test) is required for each pipe property. The mandatory Project Specific Assessment will lead to a long process and additional cost

• FE Analysis approx 3 months & cost about USD 120000• Full scale Testapprox 4-5 months (including material test delivery & cost about USD 140000• Testing Material cost about USD 2900/ton

The associated risks:• Uncertainty due to the change of some design variable such as pressure & temperature profile, corrosion allowance, wall

thickness, pipeline routing that affect free span and on-bottom roughness even global buckling• Availability and Quality (coil, manufacturing, testing) of test linepipe specimen• Test linepipe late delivery• Failure during test• Resizing due change of production profile• The test loading (axial force & bending moment shall be similar with proposed lay barge characteristic. If the barge change

then the test and FE shall be re-performed !IAFMI – Technical Sharing Session


Spiral Pipe DNV JIP Phase 2 Result – Fabrication Aspect

• If DNV-OS-F101 use manufacturing, fabrication, testing, and inspection of Coil and Line pipe shall follow therequirement

• Based on track record, the manufacturer that have supplied coil and pipe manufactured to DNV-OS-F101 foroffshore application is very limited.

• Proper audits and qualifications of coil and pipe mill manufacturer shall be carried out in order to ensure that theselected ones are able to supply according to the requirements of DNV-OS-F101.

• For guidance on qualification of pipe mills reference is made to DNV-OSS-313 Pipe Mill and Coating Yard-Qualification.

• Due to difference in material strength characteristics of the plate between the inner and outer cores of the hot rolledcoils, the pipe material should be tested for various positions on the coil as part of the MPQT in order to documentconsistent properties at different location along the coil.

• Additional tensile test shall be carried out on manufactured pipe in the direction parallel and perpendicular to the coilrolling direction.

• As part of MPQT, pipe mill is required to carry out full scale weldability trials to ensure that the material producedcan be welded on the lay barge without significant or excessive precaution. The intention is that during pipeinstallation, the welding execution can meet the expectations of the installation Contractor in terms of welding speedand pipe material mechanical properties on HAZ.


Spiral Pipe DNV JIP Result – Construction Aspect DNV OS F101 allow the application of load

control (plastic strain base) within overbendregion for pipeline installation acceptancecriteria, however not for SAWH linepipe Itwas confirmed during FEA and 3-bend FullScale Test that SAWH already buckle prior toentering plastic strain region.

Due constraints of load control criteria withinoverbend region will reduce the acceptancecapability range of the proposed barge project specific assessment is required toinvestigate local buckling and fatigue duringpipelay in accordance to chosen barge

Bigger Laybarge with higher tensioner capacitywill be required availability issues and moreexpensive cost for construction


Spiral Pipe DNV JIP Result – Major Highlights


Spiral Pipe for Offshore Application– DNV Summary

There are no design code that fully cover important aspects (as addressed in DNV JIP Phase 2) ofSAWH pipeline design even in DNV OS F101.

Project Specific Assessment (FE Analysis and Full Scale Test) SHALL be performed to assesslocal buckling, running fracture, sour service, and fatigue due to cyclic loading. It is not compatiblewith fast track project type i.e Basic Engineering Stage is required only 4-5 months duration.

Due to the restriction of using displacement control acceptance criteria, Bigger pipelay barge withhigh capacity tensioner can be required to lay SAWH pipeline in certain water depth.

SAWH pipe manufacturing, fabrication, testing, and inspection of Coil and Line pipe SHALL bein accordance to DNV OS F101.

The uncertainty are reflected in the Spiral Pipe Project Guideline by requirement to projectspecific assessment (full scale test & FEA) which will necessary be a frustration for designer wholook for clear guidance

DNV JIP Phase 2 improved the knowledge of spiral welded pipe and its behavior for offshoreapplication however reveal some remaining issues (running fracture, sour service, andfatigue due to cyclic loading) to be further assessed through project specific assessment .

The guidance on qualification of pipe mills reference SHALL refer to DNV-OSS-313

SAWH pipe material SHALL be tested for varying positions on the coil as part of theMPQT

The next DNV JIP Phase 3 is required to clarify the collapse and fatigue behavior. The FEA andfull scale test will be performed. The phase – 3 result will update the content of the projectguideline. IAFMI – Technical Sharing Session


iafmi – technical sharing session presented by andi palkar

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