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Edit this text for your title. Planer for MEK 4450 Marine operasjoner. Edit this text for your sub-title Presenter name, location, date etc. Kværner ASA, June 2011. Safety moment. Installation of flexibles and cables. Typical products Rigid pipes Flexible pipes Cable and umbilicals

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edit this text for your title

Edit this text for your title

Planer for MEK 4450

Marine operasjoner

Edit this text for your sub-title

Presenter name, location, date etc.

Kværner ASA, June 2011

installation of flexibles and cables
Installation of flexibles and cables

Typical products

Rigid pipes

Flexible pipes

Cable and umbilicals

Configurations at platform

Installation aids

Installation and installation analyzes

Installation of end terminations

Regular lay

Special challenges: shallow water, deep water, slopes, turns etc

Waiting on weather

typisk produktinndeling
Typisk produktinndeling

Pipe

Rigid

Flexible

Cable

Electric

Umbilicals

Beam theory.

Axial load

Compression

Bedning moment

Courtesy: Bredero Shaw

Courtesy: NKT Flexibles

Courtesy: Nexans

Courtesy: Nexans

rigid pipe
Rigid pipe

Large diamter

Heavy

High laying tension

High bending radius

Large deck space

Expensive equipment

Plastic deformations acceptable

Rightning before over boarding

Avoid repeated plastic bending!

Thermal isolation (wax formation)

Concrete layers (gas pipes)

Courtesy: Bredero Shaw

flexible pipes
Flexible pipes

Low elastic bending radius

Less expensive laying vessels / equipment

More competition

Separate layers for

Axial load

Outer pressure

Inner pressure

Courtesy: NKT Flexibles

cables
Cables

Power cables and umbilicals

Small radius, bending radius, unit weight

Less expensive vessels / equipments

High density

Huge loads on a fully loaded vessel

Structural capacity and vessel stability

Combined functionality

No plastic bending

Courtesy: Nexans

theory slide installation aids
Theory slide. Installation aids

Flexible 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 expensive vessels 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 carry the weight of the product during overboarding. The vertical U- shaped unit at the side of the vessel is called a chute 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 may be 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 forming the 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 of the vessel. The hold-back force is taken by the drum itself. In the stern part there are equipments for straightening out the pipes if there have been plastic deformations and a laying ramp for smooth transition of the product to the sea.

The last two slides shows two other options, particularly useful for laying of rigid pipes. The first case shows a vessel where the new pipe sections are welded to the pipe continuously during over boarding and laying. The huge stinger in the stern of the vessel will prevent critical over bending of the product,- plastic deformation is no longer acceptable 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 is particularily popular in deep water, while the previous solution may be more suited in shallow water.

typical installation vessels
Typical installation vessels

Installation vessel with horizontal caterpillar og chute

Installation vessel with lay tower

Pipe lay vessel with reel and lay ramp

Pipe lay vessel with stinger

Semi-submersible

Anchor vessel

DP vessel

Pipe lay vessel with J-lay tower

tensioner caterpillar
Tensioner / Caterpillar

Used to pay in / out product, and maintain tension

Belts with pads pushed toward the product. Friction

Sufficient force to

Pull in and overcome friction over chute

Keep cable in position in a storm

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

Internal friction may be lower than friction against pads.

chute
Chute

Cable installation

Smooth and even load distribution

Vessel heading restriction

At maximum design tension

Chute structural capacity

Product integrity (bending + axial load)

Over bending at tip of chute

Top angle from analyses

installation vessel with lay tower
Installation vessel with lay tower

Seven Seas

Scandi Neptune

Pertinacia

stinger
Stinger

Stable support for pipes

Checking with analysis

Rollers to reduce friction

Point loads

Stinger radius below elastic bending radius

Departure angle high enough to ensure smooth exit

Avoid lift-up of pipe in whole stinger

May impact vessel motion characteristics

NOTE: picture shows stinger in elevated, not operational mode

typical laying situation
Typical laying situation

Picture displaying vessel, water depth, product, and key geometric parameters

a salesman s death
A salesman's death

Oppgaven var: en selger vil skaffe firmaet ditt en jobb der en kabel med gitt en gitt kabel skal installeres av et fartøy som tåler et

gitt toppstrekk. Bør du gripe inn?

D=1000m

W=10 kg/m

R=5m

H=500N

Bunnstrekk:

=0.29 deg!

Toppvinkel:

T=100500N

Toppstrekk:

Avstand til touchdown:

X=29.98m

hvor

H = Horisontalt strekk i produktet i touchdown [N]

w = Neddykket produktvekt [N/m]

R = Minste bøyeradius over touchdown (i ”sag bend”) [m]

a = Produktvinkel med vertikalen [radianer]

D = Vanndyp [m]

T = Produktstrekk i øverste ende [N]

X = Avstand mellom toppunktet og touchdown

installation analyses
Installation analyses

Establish weather criteria and a plan for laying. (Laying tables)

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

Low tension: over bending, axial compression, loop formation

High tension: rupture, tensioner capacity, free spans

Determine and verify survival conditions

survival condition
Survival condition

Cutting of product.

More critical for power cables and umbilicals

Installation of buoyancy elements

Establish flexible ”S”- shaped configuration

Step by step analysis to ensure product capacity while over boarding buoyancy

Analysis gives guidance in when to pay in / pay out after installation

Analyses: can the vessel maintain heading and position?

steep slopes
Steep slopes

Uncontrolled sliding of the product

Axial compression

Free span formation

Anchor at top of slope?

Another anchor further down?

other special considerations
Other special considerations

Deep water

High top tension, tensioner and chute capacity

Combined tension and bending at vessel interface

Curve lay

Sliding of product

Low laying tension

Laying around preinstalled piles etc

power cable umbilical from shore to offshore
Power cable/umbilical from shore to offshore

First end to shore:

Shallow conditions:

Attach buoyancy elements

Floating

Onshore winch pulls in through ditches or tunnels

Friction, uncertain factor

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

Last end to shore:

More complicated floating

power cable umbilical from shore to offshore1
Power cable/umbilical from shore to offshore

Platform end:

Installation through platform J- tubes

Platform 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, platform managers and other unsteady phenomenon.

Floating platform offset

Clash with mooring lines, other risers etc

Over bending at start of J tube

power cable umbilical from shore to offshore2
Power cable/umbilical from shore to offshore

Installation of buoyancy elements:

A “S”- shaped cable configurations at platform may be required.

Buoyancy elements in final stages

Use of clump weights or sea bed abnchoring may also be required

power cable umbilical from shore to offshore3
Power cable/umbilical from shore to offshore

Challenges

Compression / overbending near termination of buoyancy elements, touch down etc

Clump weight tangles up

Analyses to determine vessel movements and clump weight

power cable umbilical from shore to offshore4
Power cable/umbilical from shore to offshore

Subsea termination

Heavy end termination for subsea plug-in

Bending 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 and termination during lowering

Calculate design loads for product loading