static analysis report Rev-A.pdf

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LEIGHTON INDIA – ENGINEERING & CONSTRUCTION

BINA REFINERY PROJECT

PIPELAY ANALYSISSTATIC CONDITION

Document Ref. No.: IO185-ENG-REP-004

AAugust 11,

2008

Issued forClient

CommentsRK GL GP

Revision Date Description Originator Reviewed Approved Client


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Leighton India – Engineering & Construction Bina Refinery ProjectPipelay analysis - Static


PIPELAY ANALYSIS

STATIC CONDITION

August-2008 Page 2 of 16 IO185-ENG-REP-004 (Rev A)

TABLE OF CONTENTS

Sections Description Page

1.0 INTRODUCTION 3

1.1 Project Description 3

1.2 Scope of Procedure 3

1.3 System Of units 41.4 Nomenclature 4

2.0 SAFETY 5

3.0 RESPONSIBILITIES 6

4.0 REFERENCES 74.1 Project Specification 7

4.2 Project Drawings 7

4.3 Codes and Standards 7

5.0 DESIGN DATA 8

5.1 Pipeline Data 8

5.2 Lay barge Data 8

5.3 Roller Position on Lay-barge and Stinger 9

6.0 METHODOLOGY 106.1 Pipelay Static analyses 10

6.2 Description of “OFFPIPE” 11

7.0 RESULTS 12

7.1 Static analyses 12

8.0 CONCLUSION 13

Appendices

Appendix 1.0 Leighton “STEALTH” Pipe-Laybarge Configuration 14

Appendix 2.0 Static Analyses – OFFPIPE output 15

Appendix 3.0 Local Buckling Checks 16


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1.0 INTRODUCTION

1.1 Project Description

M/s Bharat Oman Refineries Ltd. (BORL) is setting up a 6.00 MMTPAgrass root refinery at Bina in India. As part of Bina Refinery Project, M/sBharat Oman Refineries Limited (BORL) intend to install a Single PointMooring (SPM) system and approximately 17.0 km long 1219mm (48”)diameter offshore/onshore crude oil pipeline from SPM to Crude OilTerminal (COT) at Vadinar for unloading/ transportation of crude oilreceived through ocean tankers.

Leighton scope of work includes the following:

Installation of SPM & PLEM System (at approx. 32 m water depth)including Piling

Installation of 1219mm (48”) diameter, approx. 15.0 km longsubmarine pipeline with concrete coating including laying in shoreapproach

Installation of 1219mm (48”) diameter, approx. 2.0 km long onshorepipeline including terminal piping works at COT

1.1 SCOPE OF REPORT

The scope of this report includes the following:

Normal pipelay analysis for static conditions during the pipe-layoperation from Leighton barge – STEALTH.

1.2 PURPOSE

The purpose of this report is to establish the following:

To find out the stresses in the pipeline during the pipe laying at

different water depths along the proposed pipeline route andthereby establish that the pipe-laying activity is performed keepingthe pipe stresses within the permissible limits.

This analysis is done to find out the Stinger tip, Bottom tension attouch down, Suspended span length, Maximum overbend stress,and Maximum sagbend stress.


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1.3 SYSTEM OF UNITS

The International system (SI) of units is adopted as the main system of thepipelay analysis.

1.4 NOMENCULTURE

BOP Bottom Of PipeDLB Derrick Lay BargeDnV Det norske VeritasKP Kilometer Point

LFP Land Fall Pointmm millimeterMPa MegapascalMT Metric Tonne


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2.0 SAFETY

All activities that are scheduled to be carried out in accordance with thisdocument, the contract requirements, approved Leighton SafetyProcedures and any specific job safety analysis conducted tocommencement of work.


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3.0 RESPONSIBILITIES

1. Project Manager shall be responsible for approval of this report.

2. The Construction Manager shall be responsible for implementation of the

specific aspects of this report.

3. Actions may be delegated, but responsibility shall not be delegated.

Definitions:

Use of the Word ‘shall’ within this document indicates a mandatory

requirement.Use of the word ‘should’ within this document indicates a preferred

requirement.


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4.0 REFERENCES

The latest revision of the following reference documents shall be used inconjunction with this report.

4.1 Project Specifications

Number Title

1203-001-16-56-SD-03 Geotechnical Investigation Report forSPM System

IO185-ENG-REP-001Design Premise for ResidualEngineering

4.2 Project Drawings

Number Title

1203-002-16-71-1001 to 1005 Pipeline Alignment Sheet From PLEM to LFP

1203-002-16-71-1006 to 1008 Pipeline Alignment Sheet From LFP to COT

IO185-ENG-DWG-505 Finalized Pipeline Route Drawing

4.3 Codes and standards

Codes Title

DNV - 1981 Rules for Submarine Pipeline Systems.


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5.0 DESIGN DATA

The analyses described in this document are based on the pipeline data,material properties and barge input data as provided in the followingsections. The pipelay analyses are performed using nominal pipeproperties.

5.1 Pipeline Data

The pipeline data are as per Pipeline Alignment Sheet from PLEM to LFP.(Drawing No. 1203-002-16-71-1004 & 1005) are presented in Table 5.1

Table 5.1: Pipeline Data

Sections KP 0.0 to KP 2.3& KP12.3 to LFP

KP 2.3 to KP 9.5

Outside Diameter 1219.2mm(48-in)Material Grade API 5L GRADE (X-65)Wall Thickness 20.6mmSteel Density 7850 kg/m3 Corrosion Coating Coal Tar EnamelCorrosion Coating Thickness 4.8mmConcrete Coating Thickness 100mm 130mmField Joint Coating As per EIL Spec. No.6-71-0045 Rev.2

Field Joint Coating Density 1025 kg/m3 .

5.2 Lay barge Data

Lay barge data used in the analysis is presented in Table 5.2 and thebarge configuration drawing is presented in Appendix 1.

Table 5.2: Lay barge data

Description Data

Length 100.585MBreadth 30.480MMoulded depth 6.16MOperating draft 3.6mBarge trim Varies for water depthHitch co-ordinates(wrt barge deck) Y = -2.5m, x = -0.75mNumber of tensioner 2Tensioner capacity 50 tonnes each


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Number of supports on Barge 8 (including 2 tensioner)

Crane Capacity 250 TonnesTrack Roller Capacity 100 TonnesStinger Roller Capacity 60 Tonnes

5.3 Roller Position on Laybarge and Stinger

The lay barge and stinger roller positions used in the design are presentedin Table 5.3 and Table 5.4:

Table 5.3: Roller Position on Laybarge

Sl-No. X Coordinate Y Coordinate

Roller No. 1 89.471 5.436Roller No. 2 78.873 4.93Roller No. 3 66.681 4.349Roller No. 4 54.490 3.767

Tensioner No. 1 42.425 3.191Tensioner No. 2 30.289 2.542

Roller No. 5 20.072 1.87Roller No. 6 6.02 0.62

Note: Roller positions on lay barge are based on (0, 0) barge stern coordinate

Table5.4: Stinger Roller Position

Support X Coordinate Y CoordinateRoller No. 2 -8.873 -1.198Roller No. 4 -20.072 -2.867Roller No. 6 -29.721 -4.557


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6 METHODOLOGY

6.1 Pipelay Static Analyses

The installation of the pipeline will be carried out in accordance with theDnV-1981 and the design premise document (Ref-2). The normal pipelayduring static conditions will be performed for various water depths usingOFFPIPE program. In the pipe-lay analysis following external forces willbe considered.

• Uniformly distributed weight of pipe• Applied tensions at the lay barge tensioners• External hydrostatic pressure• Reaction loads from the supporting rollers

The pipeline stresses are calculated using the equivalent stressformulations in DnV-1981 which is as below.

σe = √ (σx2 + σy

2 - σx . σy)

Where,σe = Equivalent Stress in MPaσx = Longitudinal Stress in MPaσy = Hoop Stress in MPa

6.2 Description of “OFFPIPE”

The Static analysis is performed using ‘OFFPIPE’ program. ‘OFFPIPE’ issophisticated finite element method based on commercial computerprogram. It has been developed specifically for modeling and structuralanalysis of non linear problems encountered in the installation andoperation of offshore pipelines.

‘OFFPIPE’ is based on the non linear matrix, finite element methoddeveloped specifically for analysis of flexible offshore beam and cablestructures. This method is generalization of the classical, linear Euler-Bernoulli theory traditionally used for the analysis of offshore platform andsimilar structures. This method is equivalent to the numerical (Galerkin)solution of the exact non linear differential equation of motion for acontinues beam, which is subjected to large deflections and non-linearmaterial behavior.


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The coordinates of the pipe supports and tensioners on the lay-barge arebased on the typical configuration provided by Leighton (Refer Appendix-1). These coordinates are provided in Table 5.3. The standard operationaldraft for the analysis is 3.6m and the position of the vessel is defined inthe input data by specifying the draft, heading and trim angle of the vessel.

The stinger is modeled as a rigid truss which has fixed curvature with ahinged end. The undeformed geometry of the stinger is defined by thestinger roller coordinates which are provided in Table 5.4.

The pipeline properties are modeled as per the pipeline data provided inTable 5.1. However, concrete coating stiffness is ignored for stress

computation as it is conservative.Local buckling checks are performed in accordance with the DnV-1981.


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7 RESULTS

7.1 Static Analysis.

The static analyses were carried out for water depths of 5m, 8m, 10m,20m, 25m and 30m. Table 7.1 summarises the tensions required duringpipe-lay in order to maintain the pipeline integrity during pipe-laying. Thewater depths considered are inclusive of tidal height. The detail computeroutputs are provided in Appendix 2.

The static analyses indicate that the stresses in the pipe at the overbendand sagbend were within the allowable stresses. The highest overbend

stresses recorded in the pipe is 66.92% of SMYS and highest sagbendstress is 61.21% of SMYS.

Local buckling checks were carried out to ensure that pipeline is notlocally buckled. The local buckling checks are provided in Appendix-3 andutilization ratio is less than 1 for all cases.

Table 7.1: Lay Stress Analysis Results File

NameWaterDepth

(m)

BargeTension(Tonnes)

StingerTip atDepth

(m)

BottomTension@ Touch

Down

(Tonnes)

TrimAngle(deg.)

SuspendedSpan Length

(m)

Max.Overbend

Stress(% SMYS)

Max. SagBend Stress(% SMYS)

S05m 5 40 -0.96 24.17 0 78.68 238.88(53.32) 147.38(32.90)S08m 8 50 -1.42 33.51 0 100.47 299.80(66.92) 151.57(33.83)S10m 10 30 -1.91 7.27 0 87.66 256.54(57.26) 230.86(51.53)S20m 20 60 -2.06 32.34 0 128.10 279.37(62.36) 274.21(61.21)S25m 25 40 -2.06 19.87 0 169.04 263.29(58.77) 205.43(45.86)S30m 30 40 -2.06 18.76 0 182.87 292.18(65.22) 224.04(50.01)


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8 Conclusion

The pipe-lay analyses for the 48-inch pipeline have been performed for theproposed pipe-lay barge STEALTH configuration. The normal static pipe-lay analyses performed indicate that the pipeline stresses are within theallowable limits in accordance with the DnV-1981.


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Appendix 1.0

Leighton Lay-Barge “STEALTH” Details


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Appendix 2.0

Static Analyses – OFFPIPE output


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Appendix 3.0

Local Buckling Checks

Documents

static analysis report Rev-A.pdf