Installation

PVE-Truong Dinh Hieu

THE PROPOSE OF THIS SLIDE

Give methods of installation for offshore pipeline. Offpipe User’s Guide General Model Start-up Model Abandonment Model Davit Lift Check DNV F101.

http://www.youtube.com/watch?v=ZH4FysZ55us


S lay J Lay Reel Lay Tow-in

Surface Tow

Off-Bottom Tow

1. METHODS OF INSTALLATION

PVE-Truong Dinh Hieu2.CHARACTER METHODS OF

INSTALLATION•S Lay: The S-lay is applicable in shallower water, depend on the installation vessel’s

capacity and pipe sizes, recommended to use less than 305 m (1,000 ft) of water.

In the upper part (the overbend) the curvature is controlled by the laybarge stinger ( a steel structure protruding from the stern of the vessel, that supports the pipeline on rollers). The curvature in the lower part (the sagbend) is controlled by lay tension transferred to the pipeline by tension machines gripping the pipe string on the laybarge.

• J Lay: (http://www.youtube.com/watch?v=Phqum0y1nhs) The J-Lay may be installed in water depths exceeding 2000 m . The pipeline from the surface to the seabed is one large radius bend

resulting in lower stresses than an S-lay system in the same water depth. There is no over-bend and large stinger as required in S-lay method. The horizontal forces required to maintain this configuration are much smaller than required for an S-lay system.

• Reel Lay: Reel Lay is a method of installing pipelines in the ocean from a giant reel

mounted on an offshore vessel. Pipelines are assembled at an onshore spool-base facility and spooled onto a reel which is mounted on the deck of a pipelay barge

PVE-Truong Dinh Hieu2.CHARACTER METHODS OF

INSTALLATION Reel pipelay can be used on pipelines up to 18 inches in diameter. Reeled pipelines can be installed up to 10 times faster than conventional

pipelay. The reel method reduces labor costs by permitting much of the welding, x-

raying, corrosion coating, and testing to be accomplished onshore, where labor costs are generally lower than comparable labor costs offshore.

The reeled pipeline can be installed in an S-lay method or J-lay method depending on the design of the reel vessel and the depth of water. Reel vessels can have vertical reels or horizontal reels.

• Tow Lay: In the tow methods, the pipeline is normally constructed at an onshore site

with access to the water. These methods can be used for installing pipelines across inland lakes, across wide rivers, and offshore.

This method is applied to short line, usually less than 4 km, (7 km has been laid).

The buoyancy of the line is selected and designed to verify that a controlled depth tow can be performed.

This method of installation is usually used when several flowlines are fabricated together (i.e. a bundle).


•Other Method Laying: O-lay• http://www.youtube.com/watch?v=JhyAQuUtzdg• http://www.youtube.com/watch?v=g3CtixUcWJo.• http://www.youtube.com/watch?v=ksm4QuF7dys&feature=autoplay&list

=PLD6A6A859CBC2C296&playnext=1

2.CHARACTER METHODS OF INSTALLATION

http://www.youtube.com/watch?v=JhyAQuUtzdg

http://www.youtube.com/watch?v=g3CtixUcWJo

http://www.youtube.com/watch?v=ksm4QuF7dys&feature=autoplay&list=PLD6A6A859CBC2C296&playnext=1

http://www.youtube.com/watch?v=ksm4QuF7dys&feature=autoplay&list=PLD6A6A859CBC2C296&playnext=1


Input data

Pipe data

Offpipe ModelLocal Bulking

Check

3.Pipeline Installation Analysis


1) Pipeline radius of curvature The minimum radius of curvature in the overbend region can be

calculated using the following equation (Question 1: this calculation just applied for steel , what happen for concrete coating ?):

The curvature at sag bend should be controlled and maintained so that its stress level does not exceed the limits outlined as required in API RP 111:

ovality is assumed 0.5%

A. Offpipe Model

PVE-Truong Dinh HieuA. Offpipe Model

Bending strains ε1 is not simply nominal (global) bending strains and shall include an allowance for possible strain concentrations. For example, if a pipe is reeled, the nominal bending strain in the pipe on the reel or aligner is given by:

Question 2: How could be controlled curvature of sag bend ? Increasing the tension can control the sagbend stress (decreases the

bending stresses). In shallow water barges, the increase in tension must be taken up by the

anchors. This may lead to slippage depending on the soil conditions on the seabed. Also, the increase in tension leads to a longer suspended span, which may not be desirable. This also leads to higher residual tension of the pipeline on the seabed. On the seabed, spanning of the pipeline over undulation increases with increased tension. Therefore most barges want to use the optimum amount of tension.

Question 3: How optimum amount of tension ?

PVE-Truong Dinh HieuA. Offpipe Model

The simplest model for the calculation of the relationship between tension and sagbend curvature is the catenary model (as figure side).The catenary model ignores the flexural rigidity of the pipeline.


Pipelay Initiation

Start LFP

Start CPP

I. Pipelay Start-up

a. Start LFP The laybarge is anchor about 10m water depth (near if can),

the pipeline will be pulled to shoreline by winch and cable.

The laybarge will be moved to CPP (platform) when pullhead is fixed at LFP The pipeline will be abandonment nearest CPP possible (200m form CPP to

Laybarge), because the length of laybarge and stinger is approach is 200m , they can be hit platform if continuous laying pipeline.

Question 4: What the method to connect pipeline with riser? The laybarge turn back installation riser section first, after that connect with

pipeline by Middle-spool. All the pipeline routes have a TIE-IN(WYE) point, the laybarge will be

abandonment at there (not near CPP place) after that laybarge moved the CPP and connected the pipeline with riser/spool , continuous laying to WYE point, and connected together.

B. Analysis of Installation


b. Start Platform(CPP) The laybarge will be performed using deadman anchor (DMA) start-up

method at CPP (i.e. a anchor will be laying down first, the anchor is connected with cable and pullhead, the length of cable is controlled touchdown point).

The laybarge moved to shoreline until can’t laying, pipeline will dropped/ abandonment to seabed .

The laybarge turn back, pipeline will be pulled to shoreline by winchand cable. The pipeline will be abandonment after pullhead fixed atLFP.

Question 5: What the method to connect together.

Davit lift (The laybarge lift two pullhead and welding on laybarge) http://www.youtube.com/watch?v=6oUSV3ci5m4 Diver connected togetherhttp://www.youtube.com/watch?v=cX-Zz2byQpc



II. Abandonment and Recover Due to weather condition(or other) the laybarge may be abandonment. Abandonment process is modeled by increasing the length of the laydown cable in a series of steps until pipeline is reset on seabed. • http://www.youtube.com/watch?v=XythKAClIeQ&feature=relatedIII. Normal Pipelay The profile pipe will be modeledon the support.



C. Offpipe User’s Guide



Select the output printed.

F4 or F1 for information

Enter user’s plot hardware

Print diagnostic output

The drawing’s number to plot

The graph’s number to plot in a drawing


C. Offpipe User’s GuidePipe property

Properties of pipe coating

Properties of cable, used for initiation , abandonment and recovery

Define two or more separate pipeline bound together

Define fluid contents in pipe span analyses



Enter number of pipe

The length of pipe just defined when Table index number is different 1 .(i.e. The cable is include)

Redefined Modulus of Elasticity

Unit.

SMYS

PVE-Truong Dinh HieuC. Offpipe User’s Guide

Coating property of number of pipe

The length of pipe

The length of field joint

PVE-Truong Dinh HieuC. Offpipe User’s Guide

Enter pipe tension on laybargeNote 1Defined pipe support, static position and other data on laybarge

Defined the length and tension of davit cable

Defined properties of davit cable element into support property table

Defined properties of pipe support (in support table).

Note 1: The value entered in the TENS field is the total static pipe tension applied to the pipeline on the laybarge. When multiple pipe tensioners are used, the total tension is assumed to be evenly distributed between the tensioner.

Ex. The tension 1 =100kN and the tension 2=120kN…How many tension force is required in the TENS field ?



Enter tension force.

The number of stations (pipe support, tensioners and davits) includes unsupported pipe or cable nodes

The method used to defined the elevation at each station on the laybarge.(more detail see next page)

The angle and elevation of point on laybarge can be referenced to the water surface by setting deck height.

The coordinates (X,Y) of tangent point and angle between straight pipe ramp and tangent point

The laybarge offset from initial position(only davit lift)

The coordinates (X,Y) of Stern Shoe point(final support on the laybarge)

Property of pipe support (more detail see next Page)

Noted: The minimum radius enter in this filed will be consider in Section A.1


C. Offpipe User’s GuideUsed for davit lift analysis. Or the elevation each pipe support is calculated and given explicitly.

The Radius of curvature combined with straight ramp forward of the tangent point and coordinate of tangent point (X.Y) is specified.

The Radius of curvature combined with straight ramp forward of the tangent point and coordinate of stern shoe point (X.Y) is specified.

Stern Shoe: The pipe support closest to the stern on the laybarge

Used to model small. The elevation of pipe support is defined by the coordinated and angle of the tangent point.

Used to model “J-Lay”. The coordinate of point on the pipe ramp is assuming parallel to the deck. After the ramp is rotated about upward the angle specified in APIV field (here) and the center of rotated are given in the XPIV and YPIV fields.

GEOM Option


C. Offpipe User’s GuideProperty of pipe support

X coordinate of pipe support used for all GEOM option

Y coordinate of pipe support (entered when GEOM =1 and davit lift analysis)

Type of support

Just required in davit lift analysis. The length of pipe between present davit sling and preceding davit sling.

1. Simple pipeline support: The support resist downward displacement . The pipe are free to lift off the support.

2. Pipe Tensioner or A/R winch: The support resist both upward and downward.

3. Inverted pipe support: the support resist upward displacement.

4. Full encirclement support: The support resist both upward and downward.

5. Simple axial force davit: The davit cable is modeled by simple and straight , axial force element.

5. True catenary davit :The davit cable is modeled by a curved , that is determined by weight and tension of davit cable

1oo. Un-support pipe node: Can used both pipelaying a davit lift. This point is description place additional between support point.


C. Offpipe User’s GuideDefined the stinger, geometry and structural configuration.

Defined the weights and displacements of stinger elements.

Specify the ballast contents of stinger elements.Specify the net buoyancies of stinger elements.

Defined properties of pipe support (in support table).

Defined properties of stinger (in stinger element table).


C. Offpipe User’s GuideThe number of stations (pipe support, hinges) includes unsupported pipe or cable or stinger nodesDefined the stinger geometry (more detail see next page)

Type of stinger model to be used (more detail see next page)

The coordinated of Hitch (X,Y)

The coordinated of reference point or temporary origin. Used for GEOM =1 & 2The coordinated of tangent point (X,Y).

Property of pipe support on stinger (more detail see next Page)

Noted: The minimum radius enter in this filed will be consider in Section A.1


C. Offpipe User’s Guide1. The coordinated of support on stinger will be entered (X,Y). When this option is used, the pipe radius , coordinates and angel of the tangent point must entered.

GEOM Option

2. The coordinated of support on stinger will be entered (X,Y). When this option is used, the pipe radius , X coordinates tangent must entered. Y coordinated and angled are calculated.3. The stinger element lengths and radius will be entered. When this option is used, the pipe radius , coordinates and angel of the tangent point must entered.

4. The stinger element lengths and radius will be entered. When this option is used, X coordinates tangent must entered. Y coordinated and angled are calculated.

5. The X coordinated of support on stinger will be entered. When this option is used, the pipe radius, coordinates and angel of the tangent point must entered.

6. The X coordinated of support on stinger will be entered. When this option is used, the pipe radius, X coordinates tangent must entered. Y coordinated and angled are calculated.


C. Offpipe User’s Guide1. The stinger is modeled as a rigid extension of the laybarge. No structural.

2. The stinger is modeled structurally. Except first element, the stinger is assumed straight when undeformed.

3.The stinger is modeled structurally. Undeformed shape of the stinger is assumed to be initial geometry.

4. For future use.

5. Stinger is model as a rigid extension of the laybarge. No structural, using special features provide by OFFPIPE.

6. The stinger is modeled structurally, using special features provide by OFFPIPE.

TYPE Option

Question 6: Do you understand “Structurally” and “Modeled”?



X coordinated of pipe support on stinger. Required in GEOM 1,2,5,6. The coordinate system can determined following to laybarge coordinate system or other convenient reference point on the stinger

The coordinated of reference point or temporary origin. Used for GEOM =1 & 2

Y Coordinate of pipe support on stinger, just required with GEOM 1,2

Property of pipe support on stinger

Type of supports are defined as support on laybarg .

1. Simple pipe Support

1. Tensioner not used on stinger.

3. Inverted pipe Support

4. Full Encirclement Support.

5,6. Davit not used on Stinger. 100. Un-support node

pair: a pair of pipe and stinger nodes. This nodes are not as support.

200. Un-support Pipe node : only pipe node( may be insert a force on the pipe).

300. Un-support Stinger node : only stinger node (may be description to associate elements stinger together).


C. Offpipe User’s GuideProperty of pipe support on stinger

2.Hinged 2.Hinged1.Fixed

1.Fixed

The length of stinger segment, required with GEOM =3,4


C. Offpipe User’s GuideDefined the geometry of the pipe/cable in the sagbend.

Vary the length of pipe element in the sagbend.

Enter the soil properties of seabed

Defined the velocity profile for steady current.

Model simple buoys and point floatation devices attached to pipe.Defined the seabed elevation for pipe span analysis.


C. Offpipe User’s GuideConstant pipe length to be used in the sagbend and seabed.( pipe joint length )

Insert water depth

X coordinate of free end of the pipeline on the seabed before the lift, just use in davit lift

Slope or angle of the seabed relative to the water surface. Just analysis when the seabed not parallel water surface

X coordinate of the end at point of fixity at the lower end the sagbend. Just required in the fixed span length.

Direction and heading in which the bottom slope is measured.

Estimated the length between the touchdown point and the point fixed at the end of the pipe stinger.

Estimated the length of sagbend

Specify the end condition at the lower end in the sagbend.

Specify the length of pipe span in the sagbend is to be calculated for the given pipe tension .

X coordinated of the point on the point right-of- way. This value must specified when the value of slope of seabed is entered is nonzero

Depth and vertical angle of the pipe stinger in the sagbend..only used when the free end is defined as pinned connection.

NOTE: The profile of sagbend will be calculated by OFFPIPE. This field just is required to entered water depth (other condition is relative seabed) and sagbend element length.



Stiffness of soil with pipeline displacement in the vertical direction. Static vertical deflection of the soil under. Approximated equal submerge weight of pipe.Stiffness of soil with pipeline displacement in the horizontal direction. Soil coefficient of friction used for pipeline displacement in the horizontal direction. The number of numerical integration point (default).

The number of water depth for the current velocity and direction. The water depth for the current velocity and direction are specified. Current velocity is specified.

Direction of current flow (assumed 90 degree).

Question 7: How about the wave is included in static analysis ?


D. Summary In above section, the basis parameter must used for modeled pipeline

installation by OFFPIPE software. The input data is summarized as:

How did you controlled Y coordinated of support on laybarge? (if no data)

Step 1: Calculated the curve of the pipe on the laybarge.

Step 2: The pipeline will be modeled with GEOM =4 , the coordinates of tangent point will be entered .

Step 3: Run and check allowable stress at overbend. If violate , increase the curve of the pipe as a method.


D. SummaryY coordinates of supports is defined as sum deck height and the height of support on deck.

Percent Yield of pipe on the Overbend Max 72% SMYS .and Maximum allowable strain at sag bend is 85% SMYS.(reference Appendix 1).

The method reduce percent yield of pipe on the stinger as increase tension force or reduce the curve on the singer in the *STIN field. Noted when increase tension force, or reduce the curve on the singer the percent yield of pipe on laybarge will be increased. (Be careful)

Question 8: What method to controlled percent yield of pipe on the Over bend?

Increase the curve of the pipe in *Barg field or reduce Tensioner force as a method to reduce percent yield on the laybarge.

The percent yield of the pipe in the sag bend is always smaller in the over bend (if don’t have specifically ). If user controlled percent yield on the overbend, no need to check percent yield on the sagbend.


E. Application for analysis installationI. Start Up Initial installation is start from Platform, the pipe line will be modeled

include cable as example below:

Initial installation is start near shoreline

END=1 is modeled the cable which pinned by dead man anchor.

YEND, AEND are modeled the Y coordinates and vertical angle of end cable which pinned by dead man anchor.

*LENG field is modeled as distance from first support to pullhead. This field is description as pipe segment laydown slowly to seabed .

The cable will be consider as pipe segment. In this case, the purpose of cable is fixed end of pipe or pull. Due to CABL field is defined as ROW=2


E. Application for analysis installationII. Abandonment/Recovery Abandonment and recovery : In abandonment case, the pipe will modeled as increase

the length of the cable. Recovery case will modeled as reduce the length of cable.

The cable will be consider as pipe segment. In this case, the purpose of cable is abandonment pipe. Due to CABL field is defined as ROW=1

III. Davit Lift Davit lift: Modeled pick up the free end of a pipeline

laying on the seabed Davit lift are performed in the installation of pipeline

riser (how), on fixed offshore platforms. May be also be used to reposition a pipeline laying on the seabed, to facilitate to making of a underwater connection.

Davit lift may be used to connect two section pipeline on the laybarge(Ex at shore approach).

In Davit lift analysis need controlled cable length and tensioner force to ensure percent yield not exceed.

Support used to davit lift analysis.(X,Y) coordinates

XENDDavit length


E. Application for analysis installation

Un-support node is modeled for free end (pullhead) or between two support.. X coordinate =100m and Y coordinate =2m of support 1, Type of support =6 or 5(see section C ), distance form free end to support 1=20m (spacing between slings)

GEOM=1 only used for davit lift analysis.

XEND or XTOP =120m is total length of pipe from free end (pullhead) to global coordinate system .

When the length of a davit line is specified, whether davit line is slack OFFPIPE will determined line tension. IF the tension in davit line is specified, OFFPIPE calculated the corresponding length of the davit line. The length and tension cannot both be specified for the same davit. The length of at least of one cable (nearest the free end) must always be given.Davit line tension is specified approximately equal to the weight of the pipe span between davits.



Y coordinate of the free end = 3.97m above seawater surface.

The initial length of davit line number 1 = 10m .

Support reaction of support

Maximum Percent Yield of pipe 72% SMYS.

Question 9: How do you controlled percent yield ? Increase the length of davit line or modeling lift barge displacement as addition XOFF forward X direction(+). Be careful when the method above to used will be increase support reaction of support and reduced Y coordinates of the free end. A other method is increased the tension line all the remain support as below example.



II. J Lay

Installation

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