ARCTIC PIPELINE TRANSPORT OF HYDROCARBONS

Snamprogetti October 19th, 2005

THE UNIVERSITY CENTRE IN SVALBARD (UNIS)COURSE IN ARCTIC ENGINEERING

AT-327 ARCTIC OFFSHORE ENGINEERING

OCTOBER 19, 2005

ARCTIC PIPELINE TRANSPORTOF HYDROCARBONS

Luigino VITALISnamprogetti S.p.A.

Via Toniolo 1, 61032, Fano (PU), [email protected]

Snamprogetti 2October 19th, 2005

• PROJECT DEVELOPMENT SCENARIO – GAS TO MARKET

• OFFSHORE PIPELINE TECHNOLOGY

• PIPELINE SYSTEM DESIGN PHILOSOPHY

• DESIGN PROCESS

• PIPELINE INSPECTION AND MAINTENANCE

• LIMIT STATES BASED DESIGN

• EXERCISES

OUTLINEOUTLINE


NET GAS FLOW TRADE

Ugo Romano (EniTecnologie) NATURAL GAS: FROM RESERVES TO MARKET.Conference “Gas Naturale una Fonte Affidabile e Versatile” -EniTecnologie - San Donato Milanese 14 Dicembre 2004

Net Gas Flow (bcm): TODAY

Net Gas Flow (bcm): 2030


GAS-TO-MARKET: POTENTIAL GAS IMPORT TO EU15 (EU30)

Source: FUTURE NATURAL GAS SUPPLY OPTIONS AND SUPPLY COSTS FOR EUROPE”, OME 2001

ALGERIA LYBIA EGYPT

TRINIDAD

RUSSIA

NORWAY

1

55(60) 1

73 (130)

50

5

82(90) 11 12

113 (200)

(100)90

1

35 25

113 (200)

105(115)

10

1520

NIGERIA

(120)110

2000

2010

2020

ALGERIA LYBIA EGYPT

TRINIDAD

RUSSIA

NORWAY

1

55(60) 1

73 (130)

50

5

82(90) 11 12

113 (200)

(100)90

1

35 25

113 (200)

105(115)

10

1520

NIGERIA

(120)110

2000

2010

2020

0

150

300

450

600

1 2 31999 2010 2020

GS

m3

Gas Demand Forecast 2010–2020 - UE-15Source: OME 2001

Power

Industry

Residential & Commercial

0

150

300

450

600

1 2 31999 2010 2020

GS

m3


0

150

300

450

600

1 2 31999 2010 2020

GS

m3

0

150

300

450

600

1 2 31999 2010 2020

GS

m3


Power

Industry

Residential & Commercial


Distance, km0 500040001000 2000 3000 6000

AC/DC Wire

PIPELINE

GAS to LIQUIDS:Syndiesel, DME, Methanol

LD.HC.HP.HG Pipelines

Gas

Vo

lum

e, B

CM

/yea

r

25

15

10

5

0

20

30

LNG

GAS TO MARKET OPTIONSGAS TO MARKET OPTIONS


CROSS-COUNTRY PIPELINES:CURRENT AND NEAR-TO-COME R & D OUTCOME

(Transportation cost less than 1.5 $ / MBTU)

• Long Distances (LD.): 3000 – 7000 km

• High Capacities (HC.): 15 – 30 Gsm3/y

• High Pressures (HP.): 10.0 – 15.0 MPa

• High Grades (HG.): X80 – X120 API 5L

TECHNOLOGY INNOVATION:

A UNIQUE WAY TO COST REDUCTION AND

IMPROVED RELIABILITY


2.000DISTANCE, km

4.000 6.0000 8.000

$/M

BT

U

1

2

0

3

TRANSPORTATION

WELL HEAD

TRANSIT FEES

BORDER LINE COST IN EU (2nd HALF NINTIES)

LP Land Pipelines LD.HC.HP.HG Land Pipelines

BREAKEVEN DISTANCE

BREAKEVEN DISTANCE FOR GAS TRANSPORTATION VIA PIPELINE


GAS TO MARKET OPTIONSThe key solutions of gas transport as a function of Volumes and distancies

LNG PIPELINELNG PIPELINE

SUPPLY COST FOR GAS DELIVERY TO EU15 (2010-2020)Source: “Future natural gas supply options and supply costs for europe”, OME 2001


GAS TO MARKET OPTIONS

• LNG and Onshore/Offhore Pipeline Systems are the two possible alternatives from the economical and technical point of view

• Transportation cost of unit of energy increases due to harsh and remote environment to be crossed

• Advanced engineering and technology is required for construction and operation

AND EXPORT FROM ARCTIC REGIONS?


56” GAS PIPELINERUSSIA - CHINA - JAPANWestern Siberia - Shanghai

BOLSHEKHETSKAYA

SHANGHAI

Obs

kaya

Gub

a

Western Siberia

Russian section 2700 kmRussian section 2700 km

Chinese section 3900 kmChinese section 3900 km

56” GAS PIPELINERUSSIA - CHINA - JAPANWestern Siberia - Shanghai

BOLSHEKHETSKAYA

SHANGHAI

Obs

kaya

Gub

a

Western Siberia

Russian section 2700 kmRussian section 2700 km

Chinese section 3900 kmChinese section 3900 km

0

500

1000

1500

2000

2500

3000

0 1000 2000 3000 4000 5000 6000 7000

P_km

A relevant example:

STUDY ON LD.HC.HP.HG. GAS PIPELINE FROM NORTH-EAST

RUSSIA TO CHINA

• Permafrost• Bottom roughness• Seismic activity• Slope stability• Hydro-geo hazards

POTENTIAL PROJECT SCENARIO:LD.HC.HP.HG. GAS PIPELINES CROSSING HOSTILE ENVIRONMENT


Investment and operating costs for HP (advanced X100), 6600 km pipeline for 30⋅109

Sm3/y.

78,9

5,8

9,2 6,1

Invest.+ Oper. Costs 14152 106 €Operating Costs 1433 106 €ATCI 0,0600 €/m3

HP 56 inch Single Pipeline – X 100 (fuel 0,075 $/m3)

%

%%

%

Pipeline Investment

Station Investment

Fuel

Other Operating Costs

Pipeline Investment

Station Investment

Fuel

Other Operating Costs

LD.HC.HP.HG. GAS PIPELINE FROM NORTH-EAST RUSSIA TO CHINA:A COMPETITIVE OPTION FOR GAS-TO-MARKET


Location of proposed Mackenzie Valley Gas Pipeline

30” ND – 1200 km

NEW ARCTIC PIPELINES


Location of proposed Alaska Highway Pipeline

42” ND - 2810 km e 140 bar



Poronaysk

Nogliki

Piltun

Okha

Nikolayevsk -na-Amure

Aleksandrovsk -Sakhalinskiy

Yuzhno -Sakhalinsk

Sakhalin

Island

Russia

Katangli

DeKastri NyshDetail 2

Detail 1

Boatasyn

Gas Compression(BS#2)

172 km Piltunshoreline toOPF

636 km48” Gas Line

Oil Booster(BS#2)

636 km24” Oil Line

Detail 3

Sakhalin Phase II Development ProjectOnshore Pipelines Project

The development includes :

- 20” OD oil and 20” OD gas pipelines from PiltunShoreline-Tie in Point, through a route about 172 km long, to OPF. Booster Compression Station in proximity of the Landfall of Lunskoje pipelines;

- 24” OD oil and 48” OD pipelines from OPF, through a route about 636 km long, to LNG plant and Oil Export Terminal.

The scope of work includes:

- Development of fault crossing routing, alternative crossing concepts, and design assessment alternatives

- Basic design including strength capacity assessment, pipeline response analysis, selection and qualification of crossing concepts

- Detailed design of 24 fault crossing



Detail 1

20” Gas Line

20” Oil Line

41 km PA -B to shore

17.5 km PA -A to shore

41 kmshore to

Boatasyn

Boatas

PA-B

PA-A

14” Oil Line14” Gas Line

Onshore Tie -in pointwith pig traps for allpipelines

20” Oil

172 kmPiltun

shorelineto OPF

Detail 2

4.5” glycolreturn

LUN-A

Future pipelineOPF

Booster / Compression Station No.1 (BS#1)

30” multiphase30” multiphase

20” Gas line

24” Oil

48” Gas

13.5 km LUN -A to shore7.5 km shore to OPF

LNG Tanker Non ice strengthened

2 ice breaker support vessels

LNG Plant Oil Export

Terminal

36”Loading

Line

5.5 km

Tanker ofOpportunity

Domestic SupplyOff-Take

Detail 324” Oil & Condensate Line

48”Gas Line

636 km OPFto OET

Sakhalin Phase II Development ProjectOffshore Pipeline & Cables project

The SAKHALIN II Project is a development ofOffshore oil and gas field on the north-eastern shelf of Sakhalin Island, Russia. There are two production fields associated with the project. Piltun-Astokhshoye (PA) is an oil field with associated gas and Lunskoye(LUN) is a gas field with associated condensate.The offshore pipeline system includes:Piltun Location

14-inch ND x 17.5 km Gas Pipeline Expansion Spool, J-Tubepull-in from the existing PA-A platform to shore14-inch ND x 17.5 km Oil Pipeline, Expansion Spool, & J-Tube pull-in from the existing PA-A platform to shore14-inch ND x 41 km Gas Pipeline & Expansion Spool from PA-B to shore14-inch ND x 41 km Oil Pipeline & Expansion Spool from PA-B to shore

Lunskoye Location2 x 30-inch ND x 13.5 km Multiphase Pipelines & Expansion

Spools from LUN-A to shore1 x 4.5-inch x 13.5 km MEG from the OPF landfall to LUN-ATwo power / telecom cables x 13.5 km from the OPF landfallto LUN-A including J-tube pull-in

Aniva Bay Location1 x 30-inch x 5 km Oil Export Pipeline from the OET landfall to the TLU1 x 10-inch x 1 Outfall Pipeline from the OETOne power / telecom cable from the OET landfall to the TLU,including J-Tube pull-in






• DESIGN PROCESS



• EXERCISES

OUTLINEOUTLINE


( Shallow to Ultra-deep water trunklines for international gas network.

Trunklines (rigid steel), long (~ 102 km) and generally large diameter (> 16” OD), transporting hydrocarbons mostly sweet gas at high pressure (> 10 MPa).

( Inter-field (special) pipelines /flowlines for shallow to ultra-deep waters offshore production systems.

Interfield (rigid or flexible) pipelines (flowlines), short (~ 101 km) and in general small diameter (< 16” OD) pipelines transporting single or multiphase often untreated and sour hydrocarbons.

OFFSHORE PIPELINE TECHNOLOGY

PROJECT DEVELOPMENT SCENARIO


KEY ISSUES FOR DEEP WATERS TRUNKLINES

• Materials & Line Pipe Technology

• Installation Vessels & Equipment

OFFSHORE PIPELINES: THE NEW CHALLENGES


DEEP WATER FIELD DEVELOPMENTIncludingIncluding:

• Drilling and completion systems

• Surface and subsea structures

• Floating and subsea production systems

andand

• RISERS, FLOWLINES, AND EXPORT PIPELINES

(SPECIAL e. g. insulated, C.R.A., P.I.P., etc.)



Deep Waters vs. Shallow to Medium Waters

Technical Challenges

DESIGN - thick line pipe, high grade steel- reliability-based design criteria- survey

CONSTRUCTION - lay equipment- intervention work technology

OPERATION - inspection, maintenance- repair

Technical Feasibility

Bottom roughness, geo-hazards, lay-ability, pipeline integrity criteria



2) GREEN STREAM PIPELINEKP0 KP100 KP200 KP300 KP400 KP500 KP600 KP700 KP800 KP900 KP1000 KP1100 KP1200 KP1300

-3000-2500-2000-1500-1000

-5000

Dep

th (m

)

-3000-2500-2000-1500-1000-5000

200000 E 400000 E 600000 E 800000 E 1000000 E 1200000 E

2400

000

N26

0000

0 N

2800

000

N

2400

000

N26

0000

0 N

2800

000

N

-4000 m

-3500 m

-3000 m

-2500 m

-2000 m

-1500 m

-1000 m

-500 m

0 m

500 m

1000 m

4) IRAN to INDIA PIPELINE

3) ALGERIA to SPAIN PIPELINE

Tuapse

Izobilnoye

Tuapse

Izobilnoye

1) BLUE STREAM Pipeline


• traditional and challenging offshore pipeline projects; (ultra-deep, harsh environments, bottom roughness, geo hazards, severe service conditions etc…)

• frontier areas pipeline projects;(arctic and sub-arctic, severe seismic environments etc…)

CURRENT PIPELINE SYSTEMS PROJECTSCURRENT PIPELINE SYSTEMS PROJECTS


• Harsh Environments• Ice gouging in the shallow water areas ( < 25 - 30 m )• Severe seismic environment

• Rationalization of pipeline system design philosophy

• Limit state based design to optimise offshore pipeline system from the technical and economical point of view in relation to hazards

• Advanced technology for design, line pipe fabrication, construction and Inspection/Monitoring and Repair

DESIGN ISSUES FOR OFFSHORE PIPELINES IN ARCTIC ENVIRONMENTDESIGN ISSUES FOR OFFSHORE PIPELINES IN ARCTIC ENVIRONMENT


OUTLINEOUTLINE




• DESIGN PROCESS



• EXERCISES


Designer must guarantee the compliance of the whole system with the safety targets and standards, with design

responsibilities in charge to other functions

IDENTIFICATION OF CRITERIA AND PHILOSOPHIES(with reference to rules, standards, contractual requirements)

HSE PlanHSE Plan

DEVELOPMENT SAFETY ANALYSES AND REVIEWS

HAZARD IDENTIFICATIONHAZARD IDENTIFICATIONHSE REVIEWSHSE REVIEWS

ProceduresProcedures WHAT / IF ANALYSISWHAT / IF ANALYSIS

EVALUATION OF RESIDUAL RISK COMPARISON WITH ESTABLISHED CRITERIA

QUANTITATIVE RISK ANALYSISQUANTITATIVE RISK ANALYSIS

REQUIREMENTS FORREQUIREMENTS FORINSPECTION ANDINSPECTION AND

MAINTENANCEMAINTENANCE

Pipeline System Design Philosophy


92148Fittings

3139Flexible lines

65209Steel lines

No. of Incidents Resultingin a Loss of Containment

No. of Incidentsto Operating Pipelines

N/AN/A1SPM (single point mooring)

9,3x10-5289 52227Mid Line (outside Platformor Well Safety Zone)

2.3x10-32 5866Within Subsea Well Safety Zone

1.1x10-316 77618Within Platform Safety Zone

7.2x10-416 77612Riser

N/AN/A1Platform

Leak Frequency(km-year)

Operating Experience(km-years)

No. of Incidents Resultingin a Loss of Containment

20 %9 %14 %57 %

Rupture> 80 mm20 - 80 mm< 20 mm

Equivalent hole diameter (mm)

INCIDENTS TO OPERATING LINES

LEAK FREQUENCY FOR OPERATING STEEL LINES

EQUIVALENT HOLE SIZE DISTRIBUTIONS FOR OPERATING STEEL LINES

PARLOC

2001


ANALYSES OF 30 YEARS OF INCIDENT DATA

- European Gas Pipeline Data Group

- Western – European Cross-Country Pipeline

- US Department of Tranportation, Office of Pipeline Safety, Research and Special Program Administration

show US and European pipelines becoming safer.

• Gas pipeline annual failure rate from 0.8÷1.5 to 0.15÷0.21 x 10-3/ km-year

• Oil pipeline annual failure rate from 1.2÷1.8 to 0.30÷0.60 x 10-3/ km-year

SATISFACTORY PERFORMANCE


PIPELINE SAFETY DESIGN PHILOSOPHYin accordance with DNV OS-F101, 2000

• Fluid Classification

• Location Class Definition

• Serviceability vs. Ultimate Limit States

• Safety Class Approach

Safety Targets from Industry Standards,

Failure Statistics and Current Design Criteria vs. Performance.


FLUID CLASSIFICATION


Gases or liquids, not specifically identified in table, shall beclassified in the category containing substances most similar in hazard potential to those quoted. If the fluid category is not clear, the most hazardous category shall be assumed.

E


LOCATION CLASS DEFINITION

PIPELINE SAFETY DESIGN PHILOSOPHYin accordance WITH DNV OS-F101, 2000


SAFETY CLASS APPROACH


Safety Class LOW where failure implies low risks of human injury and minor environmental and economic consequences.

Safety Class NORMAL for conditions where failure implies riskof human injury, significantenvironmental pollution or very high economic consequences.

Safety Class HIGH for conditions where failure implies high risk of human injury, significantenvironmental pollution or very higheconomic consequences.



IDENTIFICATION OF SAFETY CLASSES


TARGET SAFETY LEVELS



IMR

The ideal safety path


PIPELINE SYSTEM DESIGN PHILOSOPHYfrom prescriptive to goal settings design

Hazard Identification

The HAZID Analysis shall be carried out by the Project design specialists in order to:

• identify novel or unforeseen sources of hazard;• verify that the hazards and causes are credible;• confirm controls already adopted by the Project;• comment on Occurrence and Severity ratings;• reply to recommendations put forward during the study.


PIPELINE SYSTEM DESIGN PHILOSOPHYfrom prescriptive to goal settings design

design loads identification

Design Standard Application

Hazard Identification

Residual Risks Evaluation

Residual Risks Comparison with Project Acceptance Criteria

Acceptable?

Project Design

Incorporate Risk Reduction Measures

Yes

No

Environmental Loads

Accidental Loads

Construction Loads

Other Loads

HSE Objective

Operational Loads

SafetyStudies

Design Standards

Accidental Loads

Anchoring

Fishing Activities

Environmental Loads (Freq <10-2)

Vessel Impact

Dropped Objects

Sinking

Grounding

Safety Studies


OFFHSORE PIPELINE SAFETY

• A worldwide attention to sustainable risk in a context of increasingly congestioned/interfering-with-human-activities pipeline system for gathering and transportation of hydrocarbons;

• The ageing of important offshore pipeline systems calling for increased inspection and, sometimes, rehabilitation with new operational strategies beyond those envisaged at the design stage;

• A general interest in developing International Standards and design guidelines reflecting current pipeline technology and complying with quantitative safety targets.

Show that the performance of modern pipeline systems, built during the last two decades and designed in compliance with design formats and criteria in force since the Sixties, over 30 years of operation is satisfactory: 10-3 ÷ 10-4 misfit / year-km.

Market growing, strategical services security of supply need high performances.

Can we do better or at least the same for Arctic and Sub-arctic Pipelines?

Performance studies based on both failure statistics and analytical approaches motivated by:





• DESIGN PROCESS



• EXERCISES

OUTLINEOUTLINE


from exploration through production to export

FIELDS OF APPLICATION


Pipeline Design: a multidisciplinary approach


ONON--SHORE PIPELINE DESIGNSHORE PIPELINE DESIGN

PIPELINE ROUTESELECTION AND STUDIES BASIC AND DETAILED

DESIGNENGINEERING DURING

CONSTRUCTION

• DATA COLLECTION, FIELDINVESTIGATIONS AND TESTS

• SIZING OF LINE PIPES• DESIGN OF PIPELINES AND

RELATED CIVIL AND MECHANICAL WORKS

• DOCUMENTS AND REPORTSFOR PERMITS ANDAUTHORIZATIONS

• DOCUMENTS FOR CONSTRUCTION CONTRACTS

• DESIGN OF SPECIAL SECTIONS• MATERIAL LIST AND

SPECIFICATIONS

• DESIGN FOR SPECIFICSITE CONDITIONS

• ASSISTANCE DURING CONSTRUCTION

• LAND RESTORATION WORKS

• AS-BUILT DRAWINGS

• PIPELINE CORRIDORDEFINITION

• ROUTE SURVEYS• ANALYSIS OF TECHNICAL

AND PHYSICAL CONSTRAINTS(CODES AND LAWS,HYDROGEOLOGY, SEISMICRISKS, MASTER PLANS,PROTECTED AREAS, ARCHAEOLOGICAL AREAS)

• ENVIRONMENTAL IMPACTEVALUATION

• LAND RESTORATION


ONON--SHORE PIPELINE DESIGN IN ARCTIC ENVIRONMENTSHORE PIPELINE DESIGN IN ARCTIC ENVIRONMENT

Pipeline design shall be assessed in relation to the permafrost related hazards, envisaged along the onshore pipeline routed, particularly:

• Permafrost condition and relevant phenomena (thermo-karsts etc.) site specific

• Seasonal variation at soil surface and impact on pipeline support and/or trench solution

• Pipeline response analysis under environmental conditions

• Strength and Deformation Capacity vs. Ordinary and Extreme Loads aiming to define steel grade and material requirements in relation to longitudinal deformability



Pipeline design of a gas pipeline in the Arctic and Sub-arctic Environment can be pursued by an aboveground or underground solution, particularly:

• The aboveground solution offers the following advantages: preserving the tundra upper cover, the possibility to create reliable construction design, the accessibility for inspection and control. Different types of aboveground pipeline solutions are utilized, at present the pile supported pipelines are typical.

• As regards the underground solution, the reliable operation of underground gas pipelines is limited to engineering solutions meeting real conditions and factors affecting the area.



Both solutions are generally adopted along the pipeline route depending on:

• Environmental data mainly air temperature and permafrost condition along the onshore pipeline route;

• Geotechnical data along the onshore pipeline route;• Transported fluid parameters, gas composition and gas supply and

demand requirements affecting gas hydraulics i.e. inner pressureand temperature distribution along the pipeline route;

• Selection of pipeline installation technique;• Availability of construction equipment.

Gas transportation criteria can meet low temperature requirements, while permafrost condition in relation to seismic and geotechnical morphological conditions will address whether aboveground or underground.


• PIPELINE ROUTE SELECTION

• ROUTE SURVEYS AND DATA EVALUATION

• LINE PIPE SIZING

• MATERIALS AND COATING SELECTION

• TECHNICAL DEVELOPMENTS

• ENVIRONMENTAL IMPACT EVALUATION

• STRESS ANALYSIS ON IRREGULAR SEABEDS

• FREE-SPAN DYNAMIC ANALYSIS

• LAYING ANALYSIS

• STABILITY & SCOURING ANALYSIS

• OVERWEIGHTING & TRENCHING

• INTERVENTION WORKS

• PIPELINE PROTECTION

• CROSSINGS & TIE-INS

• DOCUMENTATION FOR CONSTRUCTION CONTRACTS

• ASSISTANCE DURING CONSTRUCTION

• AS-BUILT VERIFICATIONS

• AS-BUILT DRAWINGS

• ASSISTANCE DURING IN-SERVICE INSPECTIONS

• IN-SERVICE CONDITION EVALUATIONS

• REPAIR ASSESSMENTS

• UPGRADING ANALYSES

OFFSHORE PIPELINE DESIGN

FEASIBILITY STUDY&

BASIC DESIGN

ENGINEERINGDURINGCONSTRUCTION

ENGINEERINGDURINGOPERATION

DETAILEDDESIGN


OFFSHORE PIPELINE DESIGN IN ARCTIC ENVIRONMENTSOFFSHORE PIPELINE DESIGN IN ARCTIC ENVIRONMENTS

Pipeline burial requirements shall be optimized in relation to the iceberg gouging hazards, envisaged along the offshore pipeline route, particularly:

• Strength Capacity vs. Ordinary and Extreme Loads

• Pipe Sectional Capacity under Increasing Bending Deformations• Resistance of Girth and Longitudinal Welds by Engineering

Criticality Assessment• Pipe Sectional Capacity to withstand Soil Vertical Pressure

• Pipeline-Ice Keel Protection Requirements• Ice-soil Interaction analysis aiming to define:

• Soil pressure against pipe wall as a function of depth in the soil;

• Soil deformation during ice keel-soil interaction;• Analysis of the pipeline response when subject to ice gouging.


PIPELINE SIZING AND FLOW

DATA GATHERING AND PROCESSING

MATERIAL AND STEEL GRADEOPERATIONAL DATA

ENVIRONMENTAL DATA

OTHER DESIGN DATA

SURVEY DATA

WALL THICKNESS DESIGN

DESIGN BUCKLE ARRESTORS BUCKLING CHECK

DESIGN WEIGHT COATING

SELECT PRELINARYCORROSION COATING

EVALUATE HAZARDS FISHING ETC.

PIPELINE STABILITY DESIGN

PIPELINE SPAN EVALUATION

FINALISE CORROSION COAT

THERMAL ANALYSIS

RISK ANALYSIS

PIPELINE LAYABILITYAND LOCAL BUCKLING

IS LINELAYABLE

EVALUATE OTHERPROTECTION NEEDS

IS LINESAFE

DESIGN ADDITIONALSTABILISATION

TRENCH LINEFOR 100 YEAR CASE

PREPARE ALL SPECS/DRGS

PROCUR./TENDER DOCSC.P. DESIGN/ANODES

EXPANSION LOOP DESIGN

VALVE STATION DESIGN

SHORE APPROACH DESIGN

STABILITY/PROTECTION BY WEIGHT

COATING IS SUITABLE

NO

YES

YES

NOT FOR100 YEAR CASE

1/5 YEARCASE

IS WALLSUITABLE

NO WALLINCREASE

YES

YES

NO

IS TRENCHINGACCEPTABLE

NO

NO

YES

YES

PIPELINE DESIGN

NO

Pipeline Design Process: A Multi-Disciplinary Approach


• Horizontal and vertical stability are key points for the offshore pipeline systems;

• Different procedures in accordance with internationally reconnaised code of practice are available (AGA, DnV RP E 305);

• Analysis capabilities include: • Quasi static; i.e. simplified approach that simulates the effects of external dynamic actions with static equilibrium equations;

• Full dynamic; i.e. complete simulation of the effects of a external action including dynamic effects due to the wave cinematic, pipeline mass, etc.

• Bi-dimensional models i.e. detailed investigations for “special section” of the pipeline with specific lateral constraints ( e.g. crossings, subseastructures, trench slope).

Hazard due to Surface Waves: Pipeline On-bottom Stability

Shallow water scenarios in arctic environments i.e. Sakhalin Island, North Canada etc.


Geo-morpho Hazardeous EnvironmentsTroll Oil Pipeline: The deep depression in Troll Oil Pipeline: The deep depression in FensfjordenFensfjorden

Pipeline crossing uneven seabottom in the arctic environment such as, for example, the Barents Sea.


Geo-hazard due to Impact of the Turbidity Currenton the Pipeline

Troll Oil Pipeline: Pipeline route approaching the steep Troll Oil Pipeline: Pipeline route approaching the steep wall and the bore hole exitwall and the bore hole exit

Deflected shape of a pipeline Deflected shape of a pipeline impacted by turbidity currentsimpacted by turbidity currents

Pipeline laid on an unstable area in the arctic environment such as, for example, the Barents Sea.


When the pipeline in operation presents a sequence of suspended lengths alternating between contacts with the seabed or artificial features, the assessment of the structural integrity of the pipeline under severe ground motions due to earthquakes, should account for cyclic bending stresses which might exceed environmental design criteria.

0.00

10.00

20.00

30.00

40.00

50.00

60.00

223600 223700 223800 223900 224000 224100

Seis

mic

Str

ess

Res

pons

e (M

Pa)

-190

-180

-170

-160

-150

-140

-130

223600. 223700. 223800. 223900. 224000. 224100.K. P.

Dep

th [

m ]

Hazard due to Seismic Excitationon Free Spanning Pipelines

Shallow water scenarios in arctic environments i.e. Sakhalin Island,

North Canada etc..


Sandwaves are mobile bedforms found in strong tidal current regimes and moderate wave environments.

Prediction of the sandwaves mobility during the pipeline lifetime is required to prevent and avoid unacceptable pipeline-seabed configurations.

ACTIVITIES• Hydrodynamic modelling• Sediment transport modelling• Sandwave mobility modelling• Simulation of pipeline response

to a migrating wave pattern

Hazards due to Sand Wave Mobility

Pipeline Behaviour during Sand Wave Migration



Pipe burial depth in the shore approach is strongly dependent on the expected coastal evolution. Specific studies are carried out, based on historical data (topographic surveys, satellite data

etc.) and numerical models, to forecast the potential seabed and coastline

evolution. Short term and long term modifications induced by normal and extreme wave and current conditions

are simulated and the burial depth needed to avoid possible exposure of

the pipe during its life is assessed.

Hazards due to Sea Bed Mobility in the Near Shore Areas



Soil-pipe interaction is analysed simulating the following basic phenomena:

• onset of scouring

• free-span development

• natural backfilling

• pipe self-lowering and their implications on pipe structural integrity are evaluated.

A probabilistic approach is applied for the risk assessment of free span generation, free span lengths over critical values, pipe self-burial Typical outputs of the analysis are:

• expected pipeline embedment as a function of time

• maximum expected free span length

• free span exposure as a function of length

Hazards due to Sea Bed Mobility …..



Through the analysis of soil-pipe interaction on erodible sea bed the SELF-BURIAL attitude of the system is verified and pipe weight can be optimised against this phenomenon.

In the ZEEPIPE and EUROPIPE projects, in the North Sea, this approach allowed a save of about 100 Km of post-trenching operations.

…. Self-burial Evaluation



-1050

-1025

-1000

-975

-950

16700 16750 16800 16850 16900 16950 17000 17050 17100 17150 17200

KP DISTANCE

WA

TE

R D

EP

TH

(m)

AS-LAID

OPERATING

Combined effects of pressure and temperature may lead to instability

of the pipeline with consequent lateral or vertical displacement.

Advanced analysis procedures are necessary to analyze the

possibility of occurrence of the phenomenon and to design the required mitigation measures.

Analysis aims to characterize as follows:• definition of pipeline propensity to in-service buckling• definition of propensity to develop the buckle in the lateral or vertical

direction• definition of post-buckle configuration in terms of displacements and

stresses• 3D Finite element non linear analysis

Hazard due to Severe Operating Condition


Sea Bottom/Temperature Profile

-1780.0

-1680.0

-1580.0

-1480.0

-1380.0

-1280.0

-1180.0

-1080.0

-980.0

-880.0

-780.0

-680.0

-580.0

-480.0

-380.0

-280.0

-180.0

-80.0

9000 11000 13000 15000 17000 19000 21000 23000 25000 27000 29000

Pipeline X Coordinate (m)

Wat

er D

epth

(m

)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

26.0

28.0

30.0

32.0

34.0

Dif

f. T

emp

erat

ure

(°C

)

Pipe OD 610.0 mm Pipe Wall Thickness 31.8mm (D/t 19.2)

Pipe Submerged Weight (empty) 1.5 kN/m Pipe Submerged Weight (operating) 1.95 kN/m Axial - Lateral Friction 0.5 - 0.7 Residual Lay Pull 400 kN Operating Pressure 25.0 MPa at 0.0 m Max/Min Diff. Temperature 30.1/7.9 °C

Pipe Temperature Profile during Operation:Thermal Expansion vs. Bottom Roughness

Tuapse

Izobilnoye

Tuapse

Izobilnoye

BLUE STREAM PIPELINES Hazard due to Severe Operating Condition


-1234

-1229

-1224

-1219

-1214

-1209

-1204

18100 18150 18200 18250 18300

Buckle 3

-1318

-1313

-1308

-1303

-1298

-1293

19100 19150 19200 19250 19300 19350

Buckle 4

-864

-859

-854

-849

-844

-839

-834

-829

13900 13950 14000 14050 14100

Buckle 2

-170

-160

-150

-140

-130

-120

-110

-100

9700 9750 9800 9850 9900 9950

-1727

-1726

-1725

-1724

-1723

-1722

-1721

28300 28350 28400 28450 28500 28550

Buckle 6

-1382

-1380

-1378

-1376

-1374

-1372

-1370

19950 20000 20050 20100 20150 20200

Buckle 5

Buckle 1

Pipeline X Coordinate (m)2D Analysis - Pipeline Vertical Configuration Axial friction 0.5 - Lateral friction 0.7

Pip

elin

e Z

Co

ord

inat

e (m

)

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 21000 22000 23000 24000 25000 26000 27000 28000 29000

Rel

ativ

e V

erti

cal D

isp

lace

men

t [m

]

2D Analysis - Pressure

2D Analysis - Temperature

Pipeline X Coordinate (m)2D Analysis - Pipeline Vertical Configuration Axial friction 0.5 - Lateral friction 0.7

-3.0E+6

-2.0E+6

-1.0E+6

0.0E+0

1.0E+6

2.0E+6

3.0E+6

4.0E+6

9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 21000 22000 23000 24000 25000 26000 27000 28000 29000

Ver

tica

ll B

end

ing

SM

2 (N

*m)

Temperature - 2D Response

2D FE Analysisto define how safely the pipeline copes with bottom roughness


-1425.0

-1400.0

-1375.0

-1350.0

-1325.0

-1300.0

-1275.0

-1250.0

-1225.0

-1200.0

-1175.0

-1150.0

17650 17900 18150 18400 18650 18900 19150 19400 19650 19900 20150 20400 20650

Pipeline X Co-ordinate (m)

Wat

er D

epth

(m)

-10.0

-5.0

0.0

5.0

10.0Y

Co

-ord

inat

e (m

)

Fully 3-dimensional FE Analysis to define where and how the pipeline might develop upheaval buckling at the most pronounced undulations

Advanced engineering analyses have to be carried to minimize mitigation measures against severe operating conditions in arctic environment


Buried Pipelines subject to Seismic Travelling Waves

BODY WAVES SURFACE WAVES

(A) P-waves or Compression Waves (B) S-waves or Shear Waves

(C) Rayleigh Waves (D) Love Waves

• Waves Types• Pipe Configuration• Seismic Excitation• Pipeline Response


Strike-slipReverse-slip

Surface earthquake fault

Permanent Ground Deformation – Active Faults


Fault Displacements

Permanent Ground Deformation – Active Faults

-0.5

0.0

0.5

1.0

1.5

-5 0 5 10 15

Perpendicular Distance from Fault Scarp (meters x V)

Ver

tica

l Fau

lt D

isp

lace

men

t (m

eter

s x

V)

V

0.2 V

3 V 4 V 1.5 V

V is the vertical displacement reported from field measurement.

-0.5

0.0

0.5

1.0

1.5

-5 0 5 10 15


Fau

lt N

orm

al D

isp

lace

men

t (m

eter

s x

V)

V

3 V The fault normal displacement, FN, is defined as a function of the vertical displacement, V, reported from field measurement.

Folding and/or distributed shear

Fault slip on main fault

-0.5

0.0

0.5

1.0

1.5

-10 -5 0 5 10


Fau

lt P

aral

lel D

isp

lace

men

t (m

eter

s x

FP

)

2 meters, regardless of displacement

FP is the displacement parallel to the fault strike and is independent of the observed vertical displacement.

FP


Pipeline Responsethrough FE Models

Pipeline crossing Active Faults

Differential Displacement (m)

Axi

al S

trai

n (

-)High risk seismic area, see for

example, Sakhalin Island


Hazard due to Ice Gouging

( ) H

DHn

soil eDHDu−−

⋅⋅=== 0.1Depth Burial Pipe,Depth Gouge Ice

Ice gouging morphology and pipeline threats from ice Ice gouging morphology and pipeline threats from ice keel gouging soilkeel gouging soil


Iceberg grounding the Iceberg grounding the seabottomseabottom

Hazard due to Ice Gouging

The effect of the gouging ice on a pipeline depends on the level of the pipeline with respect to the gouge, and on the deformation of the soil as the ice cuts the gouge. Within that field, one can distinguish three zones:

• An uppermost zone 1, within which the soil is first carried up into the mound in front of the ice, and then sideways into the berm;

• An intermediate zone 2, in which the soil is deformed plastically under the mound, but ultimately continues under the ice; and

• A lowest zone 3, in which the soil passes under the ice, but is subject to stresses transmitted from zone 2.


Max bending strain vs. soil cover, ice keel gouge depth and soilMax bending strain vs. soil cover, ice keel gouge depth and soil lateral resistancelateral resistance

Hazard due to Ice Gouging - Development of bending deformation

Pipeline and soil displacements Pipeline and soil displacements due to ice keel gouging in zone 2due to ice keel gouging in zone 2

2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.51

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

Gouge Depth = 2.1 m - Qu = 250 kN/mGouge Depth = 2.1 m - Qu = 450 kN/mGouge Depth = 2.5 m - Qu = 250 kN/mGouge Depth = 2.5 m - Qu = 450 kN/m

H (m)

Stra

in (

%)


•• Bending and deformation Bending and deformation capacity of pipes subject to capacity of pipes subject to axial force, inner pressure axial force, inner pressure and bending,and bending,

•• Results implemented in Results implemented in DNV OSDNV OS--F101 local F101 local buckling criterionbuckling criterion

0.500

HOTPIPE 2 - EXPERIMENTAL TESTS - PIPE SPECIMEN NO. 3BENDING MOMENT VS. CURVATURE RELATIONSHIP

0.00E+00

1.00E+05

2.00E+05

3.00E+05

4.00E+05

5.00E+05

6.00E+05

7.00E+05

8.00E+05

9.00E+05

1.00E+06

1.10E+06

1.20E+06

1.30E+06

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450AVERAGE CURVATURE (1/m)

BE

ND

ING

MO

ME

NT

(N

m)

T3 Pipe specimen t = 16.2 mm, , fo =0.0%, SMYS = 480 MPa, Mean D FE Mesh, Mid Section,

T3 Pipe specimen t = 16.2 mm, , fo =0.0%, SMYS = 480 MPa, Mean D FE Mesh, Mid Section, Triggering Force

Specimen 3 - Experimental Test

Hazard due to Ice GougingStrength capacity assessment using advanced FEM analyses and Tests


Pipeline Design in Tundra Areas

Frost Heave


Thermal Analysis

Jun

jul

sep

oct

nov

dec

jan

febmar

apr

may

Jun

aug

4

5

6

7

8

9

10

11

12

13

14

15

Month

Mon

thly

Mea

n T

empe

ratu

re fo

r S

leip

ner

Eas

ing

ton

(°C

)

Pipeline Sector from KP 444 to KP 500 Pipeline Sector from KP 500 to KP 524 Pipeline Sector from KP 524 to KP 544 Assumed Temperature Profile

WINTER SEASON

MONTHLY MEAN TEMPERATURE

TEMPERATURE PROFILES FOR DIFFERENT OPERATING

CONDITIONS

Pipeline Design in Tundra Areas


The heave is not only caused by freezing of the in-situ pore water but also by water flow to a freezing front (segregational heave). This water flow is induced by a suction gradient that develops in the frozen soil.

The frost heave after the development of ice bulb is dependent on the value of the segregation potential SPo.

The segregation potential is in general obtained from

laboratory tests.

0 1 2 3 4 5 6 7 8 9 10 11 1256789

101112131415

Time (month)

Gro

und

Tem

pera

ture

(°C

)

0 1 2 3 4 5 6 7 8 9 10 11 120

0.1

0.2

0.3

0.4

Pipe Internal Temperature -4°CPipe Internal Temperature -7°CPipe Internal Temperature -11°C

Time (month)

Seg

rega

tiona

l Hea

ve

(m)

Frost Heave Analysis

)()( TgradeSPv tPao

e ⋅⋅= ⋅


Differential Settlement due Frost Heave

Pipeline Design in Arctic Environment





• DESIGN PROCESS



• EXERCISES

OUTLINEOUTLINE


At the end of the design phase:

• Diameter, Thickness and material

• Pipeline route

• Construction technology

• Intervention works-Before construction-After construction

• Operating philosophy-Inspection and monitoring plan-Damage evaluation-Pipeline repair

Safety objective met for all relevant limit states

Pipeline Inspection and Maintenance Philosophy


Inspection/Monitoring RequirementsThe objective is to define:

•• HowHow to inspect

•• WhatWhat (and WhereWhere) to inspect

Emergency proceduresEmergency procedures&&

InterventionIntervention measuresmeasures

•• WhenWhen to inspect

Based on Based on HAZID, Risk HAZID, Risk

AnalysisAnalysisand inputs from and inputs from

designdesignGeneral CriteriaGeneral Criteria

Based on inspection results and damage

evaluation



WhatWhat (and WhereWhere) to inspect

Earthquakes vs.Earthquakes vs.

GeoGeo--hazardshazards

Possible occurring earthquakes may trigger geo-hazards events that may threaten the pipeline structural integrity. The following geo-hazards are of major concern:

– mass flows- fault displacements- soil slides and slumps- turbidity currents- Travelling waves are usually less severe that

geo-hazards

Pipeline geometry & configuration

Internal InspectionInternal Inspection

(IMU, (IMU, CaliperCaliper pig)pig)

Condition of area around PL:

Visual InspectionVisual Inspection

Leak detection:

LDS/SCADA systemLDS/SCADA system



WhatWhat (and WhereWhere) to inspect

Arctic Hazards:Arctic Hazards:

The following geo-hazards are of major concern:

– Ice gouging– Differential settlement– Erosion at landfall

Pipeline geometry & configuration

Internal InspectionInternal Inspection

(IMU, (IMU, CaliperCaliper pig)pig)

Condition of area around PL:

Visual InspectionVisual Inspection

Leak detection:

LDS/SCADA systemLDS/SCADA system



Design Philosophy

DFI

As-laid Configuration

Pre-Commissioning

Misfit? Leak?

Safety & Availability

Accidental Scenarios &Extreme EnvironmentalLoads

RFO

As-Built Configuration

Ordinary Inspection(External)

Continuous LeakDetection (SCADA)

Inspect?

Misfit?Leak?

STOP

Maintenance & Repair

NO

YES

NO

YES

YES

NO

NO

YES

Survey Data

Survey Data

ExtraordinaryInspection (External&/or Internal)

Pipeline System Inspection Procedures

vs.Emergency Response


Pipeline System Maintenance and

Repair Procedures

LeakMisfit w/out Leak

Dent Anodes etc.AntiCorrosionCoating

Repair (sectionreplacement)

Pipeline Repair

Repair?

Evaluation Criteria(Safety,Availability)

OrdinaryInspection,Leak detection(SCADA)

Shutdown?

Trenching,Graveldumping,Reinforcement

SectionReplacement

Pre-commissioning&Commissioning

YES

NO

YES

NO

Medium/largeLeak or rupture

Small Leak

Shutdown

DamageLocation

DamageLocation


External ROV Survey

Shape of pipe anomaly as predicted by FE Analysis

Shape of pipe anomaly as measured by Internal Inspection

Pipeline Monitoring and Maintenance ….Structural Integrity Diagnosis before …. Repair





• DESIGN PROCESS



• EXERCISES

OUTLINEOUTLINE


LIMIT STATE BASED DESIGN

•• Design criteria currently in use are based on Design criteria currently in use are based on allowable stressesallowable stresses and weakly related to actual and weakly related to actual failure modes.failure modes.

•• Limit state designLimit state design adopts functional relations adopts functional relations describing actual failure modes in a format describing actual failure modes in a format explicitingexpliciting load and resistance factors and refers to a load and resistance factors and refers to a rationally based safety philosophy weighting each rationally based safety philosophy weighting each design issue in relation to type of failure and nature design issue in relation to type of failure and nature of consequences and reflecting quantified safety of consequences and reflecting quantified safety targets in relevant partial safety factors.targets in relevant partial safety factors.


LSD in the Offshore/Onshore Pipeline TechnologyDeterministic vs. Reliability Approach

Reliability Methods

Deterministic Approach

Limit State Based Design (LSBD)

Working Stress Design (WSD)

Load and Resistance Factored Design (LRFD)

Probabilistic Based Design


LSD in the Offshore/Onshore Pipeline TechnologyReliability Based Limit States Design Pursuing given Safety Target

LIMIT STATES DESIGN FORMAT

Ld(γΕ ,γF, γC ,γS) < Rd (γSC ,γm)where:

Ld design load effect functionRd design resistance functionγC condition load factorγΕ environmental load factorγF functional load factorγS system safety factorη resistance usage factor

β σ

Reliability Index

Standard Deviation

Probability Distributionof Safety Margin

(R-L)

1.E-07

1,.E-06

1.,E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Reliability Index, β

Pro

bab

ility

of

Fai

lure

Pro

bab

ility

Dis

trib

uti

on Resistance

Distribution, R

Load Distribution, L

Nominal Load

Nominal Resistance

Nominal Safety

Domain

fL>1 fR<1


LSD in the Offshore/Onshore Pipeline TechnologyCalibration of Limit State Based Design Criteria

through Reliability Analysis

Limit State g(x) = R - L

Criteria, Decision

Loads, L

Long term Distr., Risk

Uncertainty fx (x)

Failure Probability

Target Safety

Capacity, R

FEM, Test

Tools

Consequences

( )[ ] ( )( )∫

≤

=≤=0xg

f dxxf0xgPP


•• ULTIMATE LIMIT STATES (ULS): ULTIMATE LIMIT STATES (ULS): BurstingBurstingCollapseCollapsePropagating BucklingPropagating BucklingLocal Buckling due to Combined LoadingLocal Buckling due to Combined LoadingFracture/Plastic CollapseFracture/Plastic CollapseRatchetingRatcheting (Accumulation of plastic deformation)(Accumulation of plastic deformation)

•• SERVICEABILITY LIMIT STATES (SLS): SERVICEABILITY LIMIT STATES (SLS): OvalizationOvalization Limit due to BendingLimit due to Bending

•• FATIGUE LIMIT STATES (FLS)FATIGUE LIMIT STATES (FLS)•• ACCIDENTAL LIMIT STATES (ALS)ACCIDENTAL LIMIT STATES (ALS)

Limit States/Failure Modes as per DNV OS-F101


LSD in the Offshore/Onshore Pipeline TechnologyRelevant Limit States (Loads vs. Failure Mechanisms)

• Internal pressure Bursting

Fracture/Plastic collapse of defected long. welds

• External pressure Collapse

Buckle propagation and/or arrest

• Combined loads Local buckling

Fracture/Plastic collapse of defected girth welds

• Variable loads Fatigue

• Operating loads Global buckling


Ultimate Limit States …

•• Failure Failure occurs when internal actions are no longer able to equilibrate occurs when internal actions are no longer able to equilibrate external loads and consequently external loads and consequently deformations are uncontrolled by any deformations are uncontrolled by any boundaryboundary

•• Deformation due to external loads are controlled or imposed by Deformation due to external loads are controlled or imposed by external boundariesexternal boundaries and and failurefailure occurs at deformation level which activate occurs at deformation level which activate material (ductile tearing, cracking etc.) or shape instabilitiesmaterial (ductile tearing, cracking etc.) or shape instabilities ((ovalizationovalization, , wrinkling and/or bulging/kinking etc.)wrinkling and/or bulging/kinking etc.)

•• Ultimate Limit States (ULS)Ultimate Limit States (ULS) for a pipeline entail structural damages which for a pipeline entail structural damages which will give rise to the release of the transported fluid into the will give rise to the release of the transported fluid into the external external environment or the flooding of the line, both in the short and lenvironment or the flooding of the line, both in the short and long termong term


Ultimate Limit States …

•• Longitudinal failureLongitudinal failure modesmodes may develop in the presence of longitudinal may develop in the presence of longitudinal defects which cause the reduction of strength capacity for the cdefects which cause the reduction of strength capacity for the containment ontainment of internal pressureof internal pressure

•• Circumferential failure modesCircumferential failure modes are associated with excessive longitudinal are associated with excessive longitudinal stresses and strains caused by external loadsstresses and strains caused by external loads

•• In relation to geoIn relation to geo--morphomorpho hazard, hazard, circumferential failure modescircumferential failure modes due to due to bending effects are of major concern.bending effects are of major concern.

The most critical condition for the The most critical condition for the localisationlocalisation of deformation is associated of deformation is associated with the development of with the development of bending strainsbending strains which may be either unbounded or which may be either unbounded or limited by external boundaries.limited by external boundaries.

Sometimes circumferential (and longitudinal) failure modes are aSometimes circumferential (and longitudinal) failure modes are activated by ctivated by the the localization of deformation in fully restrained conditionslocalization of deformation in fully restrained conditions due to high due to high temperature in combination with high pressuretemperature in combination with high pressure


LSD in the Offshore/Onshore Pipeline TechnologyTarget safety level (Pf

T) According to DNV OS-F101


LSD in the Offshore/Onshore Pipeline TechnologyRelevant Limit States (Failure Statistics)

Corros ion OutsideForces

Materialdefects

Constructiondefects

Other

47.1%

0.0%

23.5%

0.0%

29.4%

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

Corros ion OutsideForces

Materialdefects

Constructiondefects

Other

Corrosion OutsideForces

Materialdefects

Constructiondefects

Other

0.4%

99.2%

0.2% 0.0% 0.2%0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%

Corrosion OutsideForces

Materialdefects

Constructiondefects

Other

Total incident by cause in the midline zone (Offshore gas pipelines - Gulf of Mexico experience before 1980 - OD>20”), Ref./VERITAS, 1980/

Total incident by cause in the safety zone (Offshore gas pipelines - Gulf of Mexico experience before 1980 - OD>20”), Ref./VERITAS, 1980/


LSD in the Offshore/Onshore Pipeline TechnologyReliability Based Load and Resistance Factored Design (LRFD)

DESIGN CHECK (PfT=10-3)

0

0.5

1

1.5

2

2.5

3

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Stress: σL, σR

Den

sity

Fu

nct

ion

s: f

L( σ

L),

fR( σ

R)

Load

Resistance

γm; αC,

αA, αUMean ValueLoad

Characteristic Load/load effect γF; γE; γC Mean Value

Resistance

Characteristic Resistance

γSC

Design ValueLoad and Resistance

SCm

Cd

CAAAEECFFLCd

dd

RR

LLLLL

RL

γγ

γγγγγγ

⋅=

⋅⋅+⋅+⋅⋅=⋅=≤


TENSILE MODE LIMIT STATES (fracture or plastic collapse of girth welds, circumferential flaw up to through thickness thenopening mode)

COMPRESSIVE MODE LIMIT STATES (wrinkling, out-bulging and formation of a longitudinal flaw, through thickness, due to circumferential tearing instability of line pipe material)

LSD in the Offshore Pipeline TechnologyRelevant Limit States for Offshore Pipelines In Arctic Environments

under Extreme Events (Ice Keel Gouging)


OVALIZATION BUCKLING-

NO PRESSURE

WRINKLING-

INNER PRESSURE

PLASTIC STRAIN

PLOT

DEFORMED PLOT

LSD in the Offshore/Onshore Pipeline TechnologyLocal Buckling (Combined Loading)


•• Bending and deformation Bending and deformation capacity of pipes subject to capacity of pipes subject to axial force, inner pressure axial force, inner pressure and bending,and bending,

•• Results implemented in Results implemented in DNV OSDNV OS--F101 local F101 local buckling criterionbuckling criterion

0.500

HOTPIPE 2 - EXPERIMENTAL TESTS - PIPE SPECIMEN NO. 3BENDING MOMENT VS. CURVATURE RELATIONSHIP

0.00E+00

1.00E+05

2.00E+05

3.00E+05

4.00E+05

5.00E+05

6.00E+05

7.00E+05

8.00E+05

9.00E+05

1.00E+06

1.10E+06

1.20E+06

1.30E+06

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450AVERAGE CURVATURE (1/m)

BE

ND

ING

MO

ME

NT

(N

m)

T3 Pipe specimen t = 16.2 mm, , fo =0.0%, SMYS = 480 MPa, Mean D FE Mesh, Mid Section,

T3 Pipe specimen t = 16.2 mm, , fo =0.0%, SMYS = 480 MPa, Mean D FE Mesh, Mid Section, Triggering Force

Specimen 3 - Experimental Test

LSD in the Offshore/Onshore Pipeline TechnologyLocal Buckling (Combined Loading)


LSD in the Offshore/Onshore Pipeline TechnologyLCC Local Buckling (Combined Loading)

1)

12

bc

d

2

bc

d

pc

dmsc

2

pc

dmsc ≤

⋅

∆+

⋅

∆−⋅

⋅+

⋅⋅

p

p

p

p

M

M

S

S

αααγγ

αγγ

( )( )

≤

>−=

><<−+

<+=

+−=

ei

eib

ei

h

h

y

uc

03

2)(

60/0

60/1545//604.0

15/)4.0(

)1(

ppfor

ppforp

ppq

tDfor

tDfortDq

tDforq

f

f

h

β

ββα

( ) ( ) UTempYYAUTempUUb fSMYSffSMTSff

tD

tf

tD

tP ααα ,,

uy ;;

3

2

15.1

2,

3

22min −=⋅−=

⋅⋅

−⋅⋅⋅

−⋅=

1.000

1.050

1.100

1.150

1.200

1.250

0 10 20 30 40 50 60 70

Outer diameter to thickness ratio (D/t)

flo

w s

tres

s pa

ram

eter

, αc

qh = 0

qh = 0.2

qh = 0.4

qh = 0.6

qh = 0.8

fu/fy = 1.18

Effective axial force Strain hardening factor Differential Internal Pressure

Design FormatDNV OS-F101

wherewhere


LSD in the Offshore/Onshore Pipeline TechnologyDCC Local Buckling (Combined Loading)

dAAdEEdFCFD

dC,D

,,, εγεγεγγεγεε

ε

⋅+⋅+⋅⋅=

≤ ( )

( )

>

≤<

−

−

≤

=

=

⋅−⋅∆=

⋅−+⋅

⋅

60

6020100

200.1

200.1

2

5178.0

0

0

0

0

max,

23

,,

tDifunknown

tDif

tD

tDif

TY

t

tDp

fSMYS 0.01 -

D

t =

gw

dh

dh

dh

gw

uTempy

hC

α

α

σ

α

αα

σε

wherewhere

Design FormatDNV OS-F101


OD = 24”, API 5L X65, WT = 13.7mm - BENDING MOMENT VS. CURVATURE

Local Buckling Assessment by Advanced FEM Analysis


OD = 24”, API 5L X65, WT = 13.7mmBENDING MOMENT VS. MINIMUM COMPRESSIVE AXIAL STRAIN



OD = 24”, API 5L X65, WT = 13.7mmBENDING MOMENT VS. MAXIMUM COMPRESSIVE AXIAL STRAIN



OD = 24”, API 5L X52, WT = 22.2mm - BENDING MOMENT VS. CURVATURE



OD = 24”, API 5L X52, WT = 22.2mmBENDING MOMENT VS. MINIMUM COMPRESSIVE AXIAL STRAIN



OD = 24”, API 5L X52, WT = 22.2mmBENDING MOMENT VS. MAXIMUM COMPRESSIVE AXIAL STRAIN



LSD in the Offshore/Onshore Pipeline TechnologyFracture and Plastic Collapse Limit State of Defected Welds

• Fitness-For-Purpose approaches (FFP)- Fabrication Codes/Standards are based on good workmanship principles- They are somewhat arbitrary, and do not consider effect of weld flaw on

service performance- Repairing welds could introduce more severe defects, material properties

degradation

- Weld flaw is acceptable, provided that the critical conditions are not reached in service life

- Unnecessary and costly weld repairs may be avoided- FFP assessments rely on NDT input

• Engineering Criticality Assessment approaches (ECA)- Usually based on the Failure Assessment Diagram (FAD)- Explicitly include material properties (toughness, yield and tensile strength),

flaws and structure geometry, loads and load effects- Suitable for a limit state based Design- BS7910 (1999), R6 rev.4 (2001)


Girth Weld

Flaw

Calculation of acceptable and detectable flaw Calculation of acceptable and detectable flaw dimensions based on fracture/plastic collapse dimensions based on fracture/plastic collapse capacity and on the allowable applied capacity and on the allowable applied stress/strainstress/strain

√δr = √(δI / δmat ) + ρ

Lr = σn / σ Y

2c

a

2at

BS 7910FAILURE ASSESSMENT DIAGRAM (FAD)

0.00

0.20

0.40

0.60

0.80

1.00

0.00 0.20 0.40 0.60 0.80 1.00 1.20

(Plastic Collapse) Lr (F

ract

ure

) δ r

SAFE AREA

FAILURE


• The design issue: ECA, AUT/NDT, allowable load effectsfor defected girth welds



ECA - Failure Assessment Diagram - Application

Typical Stress-Strain Relationships:mean, upper bound and lower bound

0

100

200

300

400

500

600

0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0%

Strain

Stre

ss (M

Pa)

Minimum

Mean

Maximum

MISMATCHING of MaterialMISMATCHING of MaterialMechanical CharacteristicsMechanical Characteristics

Applied longitudinal stressApplied longitudinal stressdepends on the actualdepends on the actualmechanical characteristicsmechanical characteristicsof the weld material relativelyof the weld material relativelyto the base material ofto the base material ofthe nominal pipe joints.the nominal pipe joints.


FAD CONSTRAINT MODIFIED

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

0.00 0.20 0.40 0.60 0.80 1.00 1.20

Plastic Collapse, Lr

Fra

ctu

re, δ

r

SAFE AREA

FAILURE AREA

R6 (rev.4) Lev.1 MODIFIED

R6 (rev.4) Lev.1


Constraint Based ECA

FRACTURETOUGHNESS

[J, K, CTOD]

GEOMETRY / CONSTRAINT [T,Q,M]

SENB (a/W = 0.3)

CT (a/W = 0.5)

SENB (a/W = 0.5)

SENTPIPE

Defected welds in tubular are usually

«low constraint structures»FEM (ABAQUS)

Modified FADApproach, R6


Load instability curve

680

685

690

695

700

705

710

715

720

0.0 1.0 2.0 3.0 4.0

Tearing ∆a [mm]

Cri

tical

Str

ess

[Mp

a]

0.00%

0.50%

1.00%

1.50%

2.00%

2.50%

Str

ain

Stress

Strain

Maximum

X65 Maximum - Matching

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.00 0.20 0.40 0.60 0.80 1.00 1.20

Lr

√δr

FAD 2B

FAD 2B Constraint modified-R6

Increasing crack height

Increasing applied stress/strain

0.0

0.1

0.1

0.2

0.2

0.3

0.3

0.4

0.4

1.15 1.20 1.25 1.30

Resistance Curve

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Tearing - ∆a [mm]

CT

OD

[m

m]

0

100

200

300

400

500

600

700

800

900

1000

J [N

/mm

]

DESIGN CURVE

CTOD (mm)

J (N/mm)

LSD in the Offshore/Onshore Pipeline TechnologyFracture and Plastic Collapse Limit State of Defected Girth Welds

Ductile Tearing ECA


LSBD vs. Harsh Environment(Deep waters, Arctic and Sub-arctic environment, high seismic area etc.)

• LSBD and reliability methods have been developed in the last ten years through a joint effort of pipeline operators, construction Companies and design consulting Companies

• LSBD allows to optimise pipeline design as it accounts for actual failure modes including in a rational way the effects of uncertainties related to offshore pipeline construction and operation

• LSBD will be increasingly important while exploiting harsh environments and also in the rational integrity management of the huge pipeline network, both on-land and offshore, currently in service





• DESIGN PROCESS

• INSPECTION AND MAINTENANCE


• EXERCISES

OUTLINEOUTLINE


INPUT DATAPipe outer diameter, Do = 914.4 mmPipe steel wall thickness, t = 26.04 mmOuter diameter to thickness ratio, Do/t = 35.12Steel Grade = API 5L X60Minimum Specified Yield Stress, SMYS = 415 MPaMinimum Specified Tensile Strength, SMTS = 520 MPaSMYS derated factor, fy, Temp = 0 MPaSMTS derated factor, fu, Temp = 0 MPaMax yield to tensile strength factor, αh,d=(Y/T)max = 0.90Inner pressure, pi = 0 to 10 MPa

Exercise No. 1Calculate the Local buckling deformation capacity

using DCC DNV OS-F101 Design Equationi.e. limit value, functional, accidental and environmental value


dAAdEEdFCFD

dC,D

,,, εγεγεγγεγεε

ε

⋅+⋅+⋅⋅=

≤

( )

( )=

⋅−⋅∆=

⋅−+⋅

⋅

2

5178.0

max,

23

,,

TY

t

tDp

fSMYS 0.01 -

D

t =

dh

dh

dh

gw

uTempy

hC

α

σ

α

αα

σε

Displacement Controlled Condition (DCC) DNV Design Equation



εC: limit strainεF,d: applied functional strainεE,d: applied environmental strainεA,d: applied accidental strain


SYMBOL DEFINITION

εD: design strainγF: functional load factor (=1.1)γE: environmental load factor (=1.3)γA: accidental load factor (=1.0)γP: pressure load factor (=1.05)γC: functional load condition factor (=1.0)αgw: reduction factor due to girth welds (= 1.0 assumed)αh,d: maximum yield stress to ultimate tensile strength (=0.92)αu: material strength factor (=1.00 assumed)γε: pressure load factor (=2.6)∆pd = γP pi: differential design pressure with respect to water pressurepi: inner pressure ranging from 0 to 10 MPa




RESULTS: εLimit > εAccidental > εFunctional > εEnvironmental



-5.00%

-4.50%

-4.00%

-3.50%

-3.00%

-2.50%

-2.00%

-1.50%

-1.00%

-0.50%

0.00%0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00

Inner Pressure (MPa)

Min

imu

m C

om

pre

ssiv

e S

trai

n (

%)

Limit

Functional

Environmental

Accidental


INPUT DATAIce keel gouging depth, D = 2.1 and 2.5 mPipe outer diameter, Do = 914.4 mmPipe steel wall thickness, t = 26.04 mmOuter diameter to thickness ratio, Do/t = 35.12Steel Grade = API 5L X60Minimum Specified Yield Stress, SMYS = 415 MPaSMTS derated factor, fu, Temp = 0 MPaInner pressure = 0 MPaMax soil lateral resistance, q = 250 and 450 kN/mPipeline burial depth, H (top of pipe) = 2.5 to 3.5 m

Exercise No. 2Calculate maximum bending strain on a pipeline

induced by ice keel gouging


Maximum and minimum axial strains Maximum and minimum axial strains along the pipeline axis in zone 2along the pipeline axis in zone 2

Pipeline global horizontal Pipeline global horizontal displacements in zone 2displacements in zone 2

FEM Analysis Results




Simplified analytical modelSimplified analytical modelFEM global analysisFEM global analysis

Simplified Analytical Model




BASIC ASSUMPTIONSCoulomb-friction soil behaviourElasto-plastic steel material behaviourShear and steel axial force equal to zeroTwo plastic hinge form: the plastic moment, Mp, is equal to

Soil movements underneath ice keel gouging depth assumed constant across the ice keel width and given by the following equation

( ) H

DH

eDHu−⋅−

⋅⋅=7.1

0.1,D

( ) ttDSMYSM op ⋅−⋅= 2




Rotational equilibrium gives:

The rotation at each hinge, φ, is equal to

The bending strain at each hinge is distributed on a 2.5 Do pipe length

z

u=φ

q

MzMzq p

p

⋅=⇒⋅=⋅⋅

82

4

1 2

( ) ( )z

HDuD

D

D

RadiusM

qHDu o

o

o

bendbendbend

p

,

5

1

525.22

1

8,2.0 ⋅==⋅

⋅=⋅=⇐=

⋅⋅⋅ φφεε




RESULTS: Applied bending strain vs. soil cover, ice keel gouge depth and soil lateral resistance



0.00%

0.50%

1.00%

1.50%

2.00%

2.50%

3.00%

3.50%

4.00%

4.50%

2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5

Pipeline burial depth (m)

Max

imu

m b

end

ing

str

ain

(%

)

q = 250 kN/m; D = 2.1 m.

q = 450 kN/m; D = 2.1 m.

q = 250 kN/m; D = 2.5 m.

q = 450 kN/m; D = 2.5 m.

Documents

ARCTIC PIPELINE TRANSPORT OF HYDROCARBONS