sut - subsea awareness course - ew feb 2012 rev 1
TRANSCRIPT
Subsea Awareness CourseSociety for Underwater Technology
Vish Krishnamurthy – Senior Flexible Design Engineer - FDT
February 2012
Introduction
The aim of the presentation is:
To introduce rigid pipeline design and installation.
The course is high level and aims to present an overview of pipelines.
Please ask questions as we go!!!
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Contents
1. Pipeline Overview
Typical Pipeline Types
2. Pipeline Design
Design Process
3. Pipeline Installation
Methods of installation
2
Three main topics
Comparison of Rigid Pipe Vs. Flexible
Advantages of Rigid Pipe:
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Can sustain higher temperatures and pressures
Greater size range - up to 72” and higher pressure retaining
Generally cheaper to buy
For most applications cheaper (Maybe not the case for higher grade materials)
Generally used for longer lengths
Less susceptible to material degradation
1. Pipeline Overview - Rigid Pipeline Types
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Pipeline Types
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Basic Pipeline
Steel pipe (Generally carbon steel)
Corrosion coating on the outside
Corrosion allowance on the inside (additional wall thickness)
Most common type of pipeline in use subsea
May be coated with concrete to increase stability and impact protection
(Generally only 16” and upwards)
Pipeline Types
Insulated pipeline
Steel pipeline with corrosion protection and insulation coatings
Used when the product must be kept warm (e.g. wax or hydrate formation)
Called „wet insulation‟ as insulation is exposed to seawater
Minimum possible OHTC is approximately 1.5 - 4.0 W/m2.°K
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Pipeline Types
Lined pipes
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Used to protect the internal surface from corrosion.
Carbon steel pipeline.
Liner made of thermoplastic or CRA material (corrosion resistant alloy).
Plastic liners have successfully been used for water injection lines.
CRA steel alloys may be welded into the inside of the pipeline.
Pipeline Types
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Flowline (pressure retaining pipe) held and centralised in outer carrier pipe.
Gap filled with insulation.
More efficient than traditional „wet insulated‟ pipelines for high insulation
applications, high temperature or deep water.
Expensive, but possible OHTC of less than 1W/m2.°K.
Pipe-in-pipe
2. Pipeline Design
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Pipeline Design Overview
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Pipeline Design
Design Codes
Functional loads
Internal pressure
External pressure
Pressure and temperature-induced expansion
External (environmental) loads
On-bottom stability
On-bottom roughness
Spans
Protection
Installation loads
Pipeline Design Codes
Pipelines are designed using recognised standards or „design codes‟.
These design codes detail the requirements pipelines must meet.
Cover all areas of pipeline design (Corrosion, burst, installation etc…..)
Commonly used design codes are
ISO 13623 = BS EN 14161 ► PD 8010 (UK standard)
DNV Series, principally DNV OS-F101
API Series, principally API 1111
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Design Codes
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Pipeline Design
Flow Assurance
Pipeline Type
Linepipe Material & Coatings
Wall Thickness Selection
Pipeline Stability
Pipeline Expansion
Pipe Thermal Buckling
Pipeline Protection
Pipeline Design Flowchart
Flow Assurance
Flow Assurance
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Hydraulic flow calculations using preliminary production / test data.
To ensure that flow arrives at required.
Pressure
Temperature
Pipeline size ensures arrival pressure.
Pipeline insulation ensures arrival temperature.
Flow Assurance
Defines
Operating pressure
Operating temperature
Required pipeline diameter
Identifies need for any pipeline insulation
Pipeline Design utilises this Data
Flow assurance needs to consider practical aspects
Installation contractor capabilities
Available materials such as insulation materials
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Flow Assurance
Pipeline Design Flowchart
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Pipeline Design
Flow Assurance
Pipeline Types
Linepipe Material & Coatings
Wall Thickness Selection
Pipeline Stability
Pipeline Expansion
Pipe Thermal Buckling
Pipeline Protection
Linepipe
Most Common Types of Steel Pipeline
Seamless Pipe – drawn out of steel ingots
Best overall properties, but most expensive
Seam Welded Pipe – made from flat plate rolled and welded
Can be cheaper.
Limited range of diameters and wall thicknesses
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Seamless Linepipe
Piercer
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Linepipe
Seamless Linepipe
Rolling
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Linepipe
UOE (Seamwelded) Linepipe
U-Press
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Linepipe
UOE (Seamwelded) Linepipe
O-Press
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Linepipe
Pipeline Design Flowchart
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Pipeline Design
Flow Assurance
Pipeline Type
Linepipe Material & Coatings
Wall Thickness Selection
Pipeline Stability
Pipeline Expansion
Pipe Thermal Buckling
Pipeline Protection
Linepipe Material Selection
Base case = carbon steel
High strength, low cost, readily available - But is it adequate?
Typical grades are X42, X52, X60, X65, X70 (Number refers to yield in ksi).
Requires injection of corrosion inhibitors.
Corrosion resistant alloys - For corrosive fluids
13 chromium martensitic stainless steel
316L austenitic stainless steel
Duplex or Super Duplex Stainless Steel
Clad Steel – same corrosion resistance on inside, but only part of the pipe wall is
corrosion resistant
Selection depends on levels of CO2, H2S, chlorides and oxygen
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Material Selection
Corrosion Protection
Internal Corrosion
Increasing of wall thickness (Corrosion
Allowance)
Lined Pipe
External Corrosion
Cathodic protection (anodes)
“Half-shell” form
Attached to pipeline via electrical continuity lead
External corrosion coatings
Fusion bonded epoxy (FBE)
Asphalt enamel
3-layer polypropylene (PP) or polyethylene (PE)
systems
Neoprene/EPDM
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Corrosion Protection
Insulation Coatings
Transient conditions: Insulation required to maintain the minimum arrival
temperature (U Value)
Cool-down: Maintain enough heat in system during shutdown (function of density
and Cp of insulation material)
Coatings may be wet (external to steel) or dry (Pipe in pipe)
Insulation coatings
Foam or syntactic based polymers
Must withstand external pressure and operating temperature for full field life
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Wet Insulation
Material Capabilty Chart
0
20
40
60
80
100
120
140
160
180
0 1000 2000 3000 4000
Water Depth/m
Te
mp
era
ture
C
Typ
ic
al G
SP
U
De
ep
W
ate
r
Typ
ic
al G
SP
U
Mid
w
ate
r
de
pth
Typ
ic
al G
SP
U
Low
e
nd
w
ate
r
de
pth
Typ
ic
al S
PU
Typ
ic
al S
olid
P
U
Typical Deepwater PP
K value
>0.1 W/m.K
Insulation Coatings
Typical 0.15 - 0.18 W/m.K
>0
.2
W
/m
K
0.165 - 0.185 W/m.K
NB Wet temperature
capability
Pipeline Design Flowchart
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Pipeline Design
Flow Assurance
Pipeline Type
Linepipe Material & Coatings
Wall Thickness Selection
Pipeline Stability
Pipeline Expansion
Pipe Thermal Buckling
Pipeline Protection
Pressure Containment
Collapse Strength
Propagation Buckling
Installation Loads
Pressure Containment
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Pipeline Failure Mechanisms
Collapse
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Pipeline Failure Mechanisms
Local Buckling
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Pipeline Failure Mechanisms
Buckle Propagation
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Pipeline Design – Propagation Buckling
Deepwater Phenomenon
Local Collapse Runs Along Pipeline
Buckle Propagates at High Speed
Pipeline Design Flowchart
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Pipeline Design
Flow Assurance
Pipeline Type
Linepipe Material & Coatings
Wall Thickness Selection
Pipeline Stability
Pipeline Expansion
Pipe Thermal Buckling
Pipeline Protection
On-bottom Stability
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Lift Force
Drag and Inertia ForcePipe Weight
Seabed Friction and
Passive Resistance
Pipeline Design – Stability
Pipelines are subject to wave/current action
Must be stable on the seabed
To Improve On-bottom Stability
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Pipeline Design – Stability
Add weight. Thicker steel wall thickness or concrete coating
Trench below the seabed to shelter the pipe
Rock dump
Add concrete mattresses
Pipeline Design Flowchart
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Pipeline Design
Flow Assurance
Pipeline Type
Linepipe Material & Coatings
Wall Thickness Selection
Pipeline Stability
Pipeline Expansion
Pipe Thermal Buckling
Pipeline Protection
Operating Pressure and Temperature
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Pipeline Design – Thermal Loads
The effective axial force is composed of
Thermal effect
Pressure (“hoop stress”) effect
Pressure (“effective axial force”)
Residual lay tension
Typical Expansion Spools
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Pipeline Design – Expansion Spools
Pipeline Design Flowchart
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Pipeline Design
Flow Assurance
Pipeline Type
Linepipe Material & Coatings
Wall Thickness Selection
Pipeline Stability
Pipeline Expansion
Pipe Thermal Buckling
Pipeline Protection
P
P
Buckling Force
• Imperfection required to initiate buckle.
Pipeline Buckling
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Upheaval Buckling
Buried pipeline breaks through backfill.
Lateral Buckling
Pipe on seabed deflects laterally.
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Lateral
Buckling
Upheaval
Buckling
Pipeline Buckling
Buckling
Add backfill soil cover and / or rock cover
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Mitigating Upheaval Buckling Design
Mitigating Lateral Buckling Design
• Add rock cover to prevent buckling
• Allow buckling to occur at initiated points
• Lay S-Shape on Seabed
Typically 1-2 km pitch
Typically 1 km
Pipeline Buckling
Buckling mitigation
Pipeline Design Flowchart
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Pipeline Design
Flow Assurance
Pipeline Type
Linepipe Material & Coatings
Wall Thickness Selection
Pipeline Stability
Pipeline Expansion
Pipe Thermal Buckling
Pipeline Protection
Protection
Pipelines can be hit by
Dropped objects
Fishing gear
Anchors
Pipelines can withstand impact … up to a point
Denting damage is evaluated from impact energy
Protection determined on risk assessment
Pipelines – trench or rockdump
Spools – rockdump, mattresses, concrete tunnels etc.
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Pipeline Design – Protection
Pipeline Protection
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Rockdumping and Matressing
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Pipeline Protection
Ploughing and Jetting
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Pipeline Protection
Trenching and Protection
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Pipeline Protection
Pipeline Design Flowchart
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Flow Assurance
Pipeline Diameter
Linepipe Material & Coatings
Wall Thickness Selection
Pipeline Stability
Pipeline Expansion
Pipe Thermal Buckling
Pipeline Protection
Pipeline Protection
3. Pipe Installation
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Installation
Pipeline Installation
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4 main pipeline installation techniques
Reel-lay
S-lay
Bundle
J-lay
Reel-Lay
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Deep
< 3000m
Spoolbase
Stalks Fabricated from single pipes
12.2m pipes are welded
Quality checked (NDT)
Field joints are applied
Typically 1Km stalk lengths
Completed Stalk Racks
Stalks on racks awaiting vessel
for spooling
Vessel spools stalks onto reel
Reel lay
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Equipment and Function
Reel-Lay
Technip’s Pipelay Vessel Apache (2”-16” Pipe)
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Reel lay
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Seven NavicaPipe to 16” Capacity 2200Te
CSO ApachePipe to 16” Capacity 2000Te
Vessel examples
Piggyback Installation
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Installing more than one line together
Reeling Summary
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Advantages
Small offshore spread
Lay Vessel
Survey Support Vessel
Onshore fabrication of pipeline
High lay rate
Disadvantages
Smaller pipe diameter limits
More plastic bending and straightening of the pipeline
Limitation in coatings
Concrete weight coated pipe cannot be installed by reeling
Pros and cons
S-Lay
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Depth
<3000m
S-lay Operations
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Global 1201
• 162m Long
• 38m Wide
• DP Class 2
• 105m Long Stinger (Deep water)
• 39m Long Stinger (shallow water)
• 6400te Pipe Tension Capacity
• 4” – 60” Pipe
• 10 Work stations
S-Lay
Advantages
Large Pipe Diameter Range: 6 – 60” Dia
Concrete Weight Coated Pipe
Cost Effective for Long Pipelines or Campaigns and remote operations
Disadvantages
Operational Costs
„Deep‟ Water Depth Limits
Slow Transit & Operational Speeds
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S-Lay
Pros and cons
Bundles
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Bundle components
Bundles
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Bottom-Tow Bundle (GoM)
Controlled Depth Tow Method (North Sea)
Bundle Summary
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Advantages
Multiple Pipelines in Single Operation
Onshore Fabrication
Disadvantages
Repairs are Difficult
Suitable Fabrication Site Locations
Extensive Route Surveys
Pipeline Crossing Agreement
Pros and cons
J-Lay
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Very Deep
>2000m
J-lay – Vessels
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CSO Deep Blue Saipem 7000
J-lay Summary
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Advantages
Deepwater Capability
Large Pipe Dia. Range
Disadvantages
Reduced Layrate – Single Work Station
Requires Continuous Re-Supply of Pipe
Pros and cons
The end…..
Any Questions?
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