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Presenter name, location, date etc.

Planer for MEK 4450Marine operasjonerKvrner ASA, June 2011

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Safety moment

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Installation of flexibles and cables

Typical productsRigid pipesFlexible pipesCable and umbilicals

Configurations at platform

Installation aids

Installation and installation analyzesInstallation of end terminationsRegular laySpecial challenges: shallow water, deep water, slopes, turns etcWaiting on weather

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Typisk produktinndeling

PipeRigidFlexible

CableElectric

Umbilicals

Beam theory.Axial loadCompressionBedning moment

Courtesy: Bredero Shaw

Courtesy: NKT Flexibles

Courtesy: Nexans

Courtesy: Nexans

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Rigid pipe

Large diamterHeavyHigh laying tension

High bending radiusLarge deck space

Expensive equipment

Plastic deformations acceptableRightning before over boardingAvoid repeated plastic bending!

Thermal isolation (wax formation)

Concrete layers (gas pipes)

Courtesy: Bredero Shaw

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Flexible pipes

Low elastic bending radius

Less expensive laying vessels / equipmentMore competition

Separate layers forAxial loadOuter pressure

Inner pressure

Courtesy: NKT Flexibles

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CablesPower cables and umbilicals

Small radius, bending radius, unit weightLess expensive vessels / equipments

High densityHuge loads on a fully loaded vesselStructural capacity and vessel stability

Combined functionality

No plastic bending

Courtesy: Nexans

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Theory slide. Installation aidsFlexible products are installed with various types of vessels equipped with means / tools for storage and controlled

over boarding of the products. Typically, the installation of rigid steel pipes requires bigger and more expensivevessels due to the huge space and holding capacities required during deck handling and installation.

In the following slides some typical examples are given. The first example show a laying vessels for electrical cables,where the cable are stored on a horizontal turntable. A horizontal caterpillar is used, where a tensioner will carrythe weight of the product during overboarding. The vertical U- shaped unit at the side of the vessel is called achute and prevent damages to the product when it goes into the sea.

We notice that the vessel is equipped with huge crane and a large open deck space. This means that the vessel maybe used for other types of marine operations, like subsea lifting.

Separate slides display the installation equipment used by this vessel. We notice the belt with the orange pads formingthe tensioner. The pads are pushed toward the cable to ensure sufficient friction. By running the belt the cable

may be pulled in or out. The other slide shows the chute.The next slide shows an alternative configurations, where the product are routed via a vertical or almost vertical laying

tower during over boarding. The tensioner are mountd in the laying tower.

The third slide shows a vessels for pipe lay. Steel pipes are spooled on the enormous vertical drum in the centre ofthe vessel. The hold-back force is taken by the drum itself. In the stern part there are equipments forstraightening out the pipes if there have been plastic deformations and a laying ramp for smooth transition of theproduct to the sea.

The last two slides shows two other options, particularly useful for laying of rigid pipes. The first case shows a vesselwhere the new pipe sections are welded to the pipe continuously during over boarding and laying. The hugestinger in the stern of the vessel will prevent critical over bending of the product,- plastic deformation is no longeracceptable as the product are going into the sea and there are no means for straightening it out again.

The last slide displays another alternative, where huge cranes are lifting pipe segments into a vertical J-lay tower.Here the segments are welded to the pipe being laid, again continuously during laying. This solution isparticularily popular in deep water, while the previous solution may be more suited in shallow water.

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Typical installation vessels

Installation vessel with horizontal caterpillar og chuteInstallation vessel with lay tower

Pipe lay vessel with reel and lay ramp

Pipe lay vessel with stinger

Semi-submersibleAnchor vesselDP vessel

Pipe lay vessel with J-lay tower

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Installation vessel with horizontal caterpillar and chute

Aker Connector

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Tensioner / Caterpillar

Used to pay in / out product, and maintaintension

Belts with pads pushed toward the product.Friction

Sufficient force toPull in and overcome friction over chuteKeep cable in position in a storm

High tension + low radial load capacity =long tensioner / many pads

Internal friction may be lower than frictionagainst pads.

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ChuteCable installation

Smooth and even load distributionVessel heading restriction

At maximum design tensionChute structural capacityProduct integrity (bending + axial load)

Over bending at tip of chuteTop angle from analyses

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Installation vessel with lay tower

Scandi Neptune

Pertinacia

Seven Seas

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Pipe lay vessel with reel and lay ramp

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Pipe lay vessel with stinger

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Stinger

Stable support for pipes

Checking with analysis

Rollers to reduce frictionPoint loads

Stinger radius below elastic bending radius

Departure angle high enough to ensure smooth exitAvoid lift-up of pipe in whole stinger

May impact vessel motion characteristics

NOTE: picture shows stinger in elevated, not operational mode

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Pipe lay vessel with J-lay tower

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Typical laying situation

Picture displaying vessel, water depth, product, and keygeometric parameters

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A salesman's death

RwH

HDw

H1sin

)sin(1

DwT

)sin(

)cos(1ln

RX

Bunnstrekk:

Toppvinkel:

Toppstrekk:

Avstand til touchdown:

hvorH = Horisontalt strekk i produktet i touchdown [N]w = Neddykket produktvekt [N/m]R = Minste byeradius over touchdown (i sag bend) [m] = Produktvinkel med vertikalen [radianer]D = Vanndyp [m]T = Produktstrekk i verste ende [N]X = Avstand mellom toppunktet og touchdown

Oppgaven var: en selger vil skaffe firmaet ditt en jobb der en kabel med gitt en gitt kabel skal installeres av et farty som tler etgitt toppstrekk. Br du gripe inn?

D=1000mW=10 kg/mR=5m

H=500N

=0.29 deg!T=100500N

X=29.98m

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Installation analyses

Establish weather criteria and a plan for laying. (Layingtables)

Ensure robust and safe operations for personnel, equipmentand flexible product.

Low tension: over bending, axial compression, loop formation

High tension: rupture, tensioner capacity, free spans

Determine and verify survival conditions

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Survival conditionCutting of product.

More critical for power cables and umbilicals

Installation of buoyancy elementsEstablish flexible S- shaped configurationStep by step analysis to ensure product capacity while overboarding buoyancyAnalysis gives guidance in when to pay in / pay out after

installationAnalyses: can the vessel maintain heading and position?

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Steep slopes

Uncontrolled sliding of the productAxial compressionFree span formation

Anchor at top of slope?

Another anchor further down?

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Other special considerations

Deep waterHigh top tension, tensioner and chute capacityCombined tension and bending at vessel interface

Curve laySliding of productLow laying tensionLaying around preinstalled piles etc

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Power cable/umbilical from shore to offshoreFirst end to shore:

Shallow conditions:Attach buoyancy elementsFloating

Onshore winch pulls in through ditches or tunnelsFriction, uncertain factor

Actual bottom topography, strong currents etc may lead tochanges in vessel position. Robustness needed

Last end to shore:

More complicated floating

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Power cable/umbilical from shore to offshorePlatform end:

Installation through platform J- tubesPlatform winch and forerunner through J- tubes

Coupling of power cable / forerunner at vessel deck.

Pull-in through J- tubes by platform winch.

Challenges:Plans for vessel positions changed due to wind, platformmanagers and other unsteady phenomenon.

Floating platform offset

Clash with mooring lines, other risers etcOver bending at start of J tube

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Power cable/umbilical from shore to offshoreInstallation of buoyancy elements:

A S- shaped cable configurations at platform may berequired.

Buoyancy elements in final stages

Use of clump weights or sea bed abnchoring may also berequired

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Power cable/umbilical from shore to offshoreChallenges

Compression / overbending near termination of buoyancyelements, touch down etc

Clump weight tangles up

Analyses to determine vessel movements and clump weight

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Power cable/umbilical from shore to offshoreSubsea termination

Heavy end termination for subsea plug-inBending restrictor or similar at neck

Focus on bending moments at neck

Lowered by the cable: head fall over

Lowered by crane more controlled, but requires separation

Analysis

Reveal need for crane

Determine required separation between crane tip andtermination during lowering

Calculate design loads for product loading