Heavy lift installation study of offshore structures

HEAVY LIFT INSTALLATION STUDY
OF
OFFSHORE STRUCTURES

LI LIANG
(MS. Eng, NUS)

A THESIS SUBMITTED
FOR THE DEGREE OF MASTER OF ENGINEERING

DEPARTMENT OF CIVIL ENGINEERING
NATIOANL UNIVERSITY OF SINGAPORE
2004


HEAVY LIFT INSTALLATION STUDY
OF
OFFSHORE STRUCTURES

LI LIANG
(MS. Eng, NUS)

A THESIS SUBMITTED
FOR THE DEGREE OF MASTER OF ENGINEERING

DEPARTMENT OF CIVIL ENGINEERING
NATIOANL UNIVERSITY OF SINGAPORE
ii


ACKNOWLEDGMENTS

The author would like to express his sincere appreciation to his supervisor Associate
Professor Choo Yoo Sang. The author is deeply indebted to his most valuable guidance,
constructive criticism and kind understanding. Appreciation is extended to Associate
Professor Richard Liew and Dr. Ju Feng for their assistance and encouragement.

In addition, the author would like to thank the National University of Singapore for
offering the opportunity for this research project.

Finally, the author is grateful to his family, the one he loves, and all his friends, whose
encouragement, love and friendship have always been the major motivation for his study.


TABLE OF CONTENTS
CHAPTER 1
1.1
1.2
1.3

INTRODUCTION ...................................................................................... 1
Background
Objectives and Scope of Present Study
Organisation of Thesis

CHAPTER 2
2.1
2.2
2.2.1
2.2.2
2.2.3

2.2.4
2.2.5
2.2.6
2.3

REVIEW OF LIFTING DESIGN CRITERIA .......................................... 10
Review of Various Lifting Criteria
Practical Considerations for Standard Rigging Design
Sling Design Loads (SDL)
Shackle Design Loads
Lift Point Design Loads
Shackle Sizing
Tilt during Lifting
COG Shift Factor
Summary

CHAPTER 3
3.1
3.2
3.2.1
3.2.2
3.3
3.4
3.4.1
3.4.2
3.4.3
3.5
3.6

HEAVY LIFTING EQUIPMENT AND COMPONENTS....................... 24

Introduction
Heavy Lift Cranes
Crane Vessel Types
Frequently Used Crane Vessels
Heavy Lift Shackles
Heavy Lift Slings
Sling properties
Grommets versus Slings
Sling and Grommet Properties
Lift Points
Summary

CHAPTER 4
4.1
4.2
4.2.1
4.2.2
4.2.3
4.3
4.3.1
4.3.2
4.4
4.4.1
4.4.2
4.5

RIGGING THEORY AND FORMULATION ......................................... 57
Introduction
Rigging Sling System with Four Lift Points
Using Main or Jib Hook without Spreader Structure

Using Main or Jib Hook with Spreader Structure
Using Main and Jib Hooks at the Same Time
Rigging Sling System with Six Lift Points
Using Main or Jib Hook with Spreader Frame
Using Main and Jib Hooks without Spreader Structure
Rigging Sling System with Eight Lift Points
Using Main or Jib Hook with/without Spreader Structure
Using Main and Jib Hooks without Spreader Structure
Summary

i


CHAPTER 5
5.1
5.2
5.3
5.4

JACKET LIFTING.................................................................................... 78
Introduction
Vertical Lift of Jackets
Horizontal Lift of Jackets
Summary

CHAPTER 6
6.1
6.2
6.3
6.4

MODULE LIFTING.................................................................................. 88
Introduction
Vertical Module Lift and Installation
Deck Panel Flip-Over
Summary

CHAPTER 7
7.1
7.2
7.3
7.4
7.5
7.6
7.7

FPSO STRUCTURE LIFTING............................................................... 102
Introduction
Lift Procedures and Considerations for FPSO Modules
Rigging Systems with Multiple Spreader Bars
Lifting of Lower Turret
Lifting of Gas Recompression Module
Lifting of Flare Tower
Summary

CHAPTER 8
8.1
8.2
8.3
8.4

8.5
8.6

SPECIAL LIFTING FRAME DESIGN .................................................. 121
General Discussion
Effect of the Shift of the Centre of Gravity
Lift Point Forces
Padeye Checking
Trunnion Checking
Summary

CHAPTER 9 FINITE ELEMET ANALYSIS FOR LIFTING DESIGN ....................... 139
9.1
Introduction
9.2
Finite Element Analysis for Module Lifts
9.2.1 Structural and Material Details
9.2.2 Finite Element Modelling and Analysis
9.2.3 Discussions
9.3
Finite Element Analysis for Lifting Padeye Connection
9.3.1 Structural Details
9.3.2 Loading Cases
9.3.3 Finite Element Modelling
9.3.4 Result Analysis
9.4
Summary
CHAPTER 10 CONCLUSIONS AND FUTURE WORKS.......................................... 170
10.1
Conclusions

10.2
Recommendation for Future Work
BIOBLIOGRAPHY ....................................................................................................... 174
APPENDIX A FEM ANALYSIS FOR JACKET UPENDING PADEYE .................... 181

ii


Summary
Successful lift installations of heavy offshore structures require comprehensive and
detailed studies involving many engineering and geometrical constraints including
geometric configuration of the structure, its weight and centre of gravity, member
strength, rigging details, lifting crane vessel and other construction constraints. These
constraints need to be resolved efficiently in order to arrive at a cost-effective solution.

This thesis summarises the results of detailed investigations by the author involving
actual offshore engineering projects. The thesis first reviews the lift criteria adopted in
the offshore industry. The key practical considerations for selection of appropriate
crane barges, rigging components are discussed. The algorithms and formulations for
rigging systems with various number of lift points are then presented.

Practical considerations for module and jacket lifts are investigated. For deck panel
flip-over operation, the force distribution between two hooks which varies with
changing module inclined angle, is calculated consistently. Lifting procedures and
rigging systems with multiple spreader bars for Floating Production Storage &
Offloading (FPSO) modules are also studied. Emphasis is given to the design and
analysis of lifting unique components to meet the stringent installation requirements.

The thesis is reports on a versatile spreader frame design which incorporates a
combination of padeye and lifting trunnions.

Detailed finite element modelling and

analysis are conducted to analyze the lifting module and padeye connection. It is found
that finite element analysis can provide important detailed stress distributions and
limits for safety verification of lift components.
iii


Nomenclature/Abbreviation

A

-

Cross Sectional Area

AISC -

American Institute Steel Construction

API

-

American Petroleum Institute

CoG

-

Centre of Gravity

CRBL -

Calculated Rope Breaking Load

CGBL -

Calculated Grommet Breaking Load

D

-

Pin Hole Diameter of Padeye

DAF

-

Dynamic Amplification Factors

DB

-

Derrick crane Barge

Dh

-

Pin Diameter of Shackle

DNV -

Det Norske Veritas

E

-

Modulus of elasticity of Steel

Eb

-

the sling bend efficiency (reduction) factor

Et

-

Efficiency of termination method

FEM -

Finite Element Method

FEA

Finite Element Analysis

-

FPSO -

Floating Production Storage and Offloading

Fb

-

Allowable bending stress

Ft

-

Allowable Tensile stress

Fy

-

Material Yield stress

Fu

-

Steel Tensile strength

Fv

-

Allowable shear Stress

G

-

Shear Modulus of elasticity of Steel

iv


H4

-

height of hook block above module (without spreader structure), or
height of spreader above module (with spreader)

H5

-

height of hook block above spreader (with spreader), or,
=0 (without spreader)

HSE

-

Health and Safety Executive

Ix, Iy -

Moment of Inertia

Lh

-

Inside Length of Shackle

Li

-

length of ith sling

MBL -

Minimum Breaking Load

MWS -

Marine Warranty Surveyor

Rai

-

ith Cheek plate Radius of Padeye

Rm

-

Main plate Radius of Padeye

SACS -

Structural Analysis Computer System

SDL

Sling Design Load

-

SSCVs -

Semi-Submersible Crane Vessels

Sx, Sy -

Sectional Modulars

SWL -

Safe Working Load

T

-

Static Sling Load

Tci

-

ith Cheek plate thichness of Padeye

Th

-

Crane Hook Load

Tm

-

Main plate thichness of Padeye

Wh

-

Jaw width of shackle

Wh, Lh -

the width and length of hook block

Wm, Lm, Hm - the width, length and height of module, respectively
Wsp, Lsp -

width and length of spreader

v


WLL -

Shackle Working Load Limit

d

-

Sling rope diameter

fb

-

Actual bending stress

fc

-

Actual Combined stress

fcog

-

COG shift factor

ft

-

Actual Tensile stress

fv

-

Actual shear Stress

xc, yc -

location of the centre of gravity of module in local coordinate system

θi

-

angle of sling with respect to the horizontal plane

τg

-

Punching strength

vi


List of Tables

Table 2.1

Lifting Criteria comparison - Single Crane Lift

Table 2.2

Lifting Criteria comparison - Double hook Lift

Table 2.3

Dynamic Amplification Factors

Table 3.1

Some of Heavy Lifting Crane Vessels in the World

Table 3.2

Shackle Side Loading Reduction
For Screw Pin and Safety Shackles Only

Table 4.1

Formulations for rigging configurations with four lift points
(using main or jib hook block without spreader)

Table 4.2

Formulations for rigging configurations with four lift points
(using main or jib hook block with spreader structure)

Table 4.3

Formulations for rigging configurations with four lift points
(using main and jib hook blocks at the same time )

Table 4.4

Formulations for rigging configurations with six lift points

(using main or jib hook block )

Table 4.5

Formulations for rigging configurations with six lift points
(using main and jib hook blocks at the same time)

Table 4.6

Formulations for the rigging configurations with eight lift points
(using main or jib hook block at a time )

Table 4.7

Formulations for rigging configurations with eight lift points
(using main and jib hook blocks at the same time )

Table 7.1

Lifting Operation Summary for Laminaria FPSO

Table 7.2

Contingency Actions Plan / Procedure

Table 7.3

Preparation Check List

Table 7.4

Loadout Check List

Table 7.5

Installation Check List

Table 8.1

Weight and COG data

Table 8.2

Total Weight and COG

vii


Table 8.3

Member Analysis Result Summary

Table 9.1

Load factor used for lifting analysis

Table 9.2

Design value of material parameter

Table 9.3

Sample of Member Group Properties

Table 9.4

Sample of SACS Section Properties

Table 9.5

Sample of SACS Plate Group Properties

Table 9.6

Sample of SACS Plate Stiffener Properties

Table 9.7

SACS Loading Summary

Table 9.8

Sample of SACS Loading ID and Description

Table 9.9

Type of Support Constraints and Member Releases

Table 9.10

SACS Load Combinations

Table 9.11

Sample of 75% Lifting Weight Factor

Table 9.12

SACS Combined Load Summation

Table 9.13

Support Reactions

Table 9.14

Spring Reaction

Table 9.15

Sample of SACS Member Stress Listing

Table 9.16

Joint Stress Ratio Listing

Table 9.17

Sling Force Summary

Table 9.18

Dimensions and length of each tubular member

Table 9.19

Maximum stress (MPa) of each case

Table 9.20

Maximum stress (MPa) for braces

Table A.1

Member forces coming out from SACS analysis

viii


List of Figures
Figure 1.1

Thesis Organizations Vs Contents of Study

Figure 2.1

Centre of gravity (COG) shift

Figure 3.1

Lifting Equipment and Components

Figure 3.2

Saipem S7000 SSCV 14000 ton Capacity

Figure 3.3

Sheerleg Crane Vessel – Asian Hercules II : 3200 ton Capacity

Figure 3.4

Derrick Barge Crane – Thialf : 14200 ton Capacity

Figure 3.5

Derrick Lifting Barge DB101: 3150 ton Capacity

Figure 3.6

Samples of Some Shackles (Green Pin and Crosby)

Figure 3.7

Sling Forming & Cross Section

Figure 3.8

Sling Configuration

Figure 3.9

Actual usage of Slings

Figure 3.10

Lift point connections- Padeye and Trunnion

Figure 3.11

Fabricated Lifting Padeye

Figure 3.12

Actual fabricated Lifting Trunnion

Figure 3.13

Details of a Typical Padeye

Figure 4.1

Determination of rigging configuration: tasks, inputs and outputs

Figure 4.2

Rigging configuration for four-lift-point sling systems using main or jib hook block without spreader

Figure 4.3

Rigging configurations for four-lift-point sling systems using main or jib hook block and spreaders

Figure 4.4a

Rigging configuration for four-lift-point sling systems using main and jib hook blocks and spreader bars

Figure 4.4b

Hook load distribution for four-lift-point sling systems using both main and jib hook blocks

Figure 4.5a

Rigging configuration for six-lift-point sling system using main or jib hook block with spreader frame

ix


Figure 4.5b

Sling tensions for six-lift-point sling system using main or jib hook block with spreader frame

Figure 4.6a

Rigging configuration for six-lift-point sling system using both main and jib hook blocks

Figure 4.6b

Hook load distribution for six-lift-point sling systems using both main and jib hook blocks

Figure 4.7a

Rigging configuration for eight-lift-point sling system using main or jib hook block without spreader frame

Figure 4.7b

Rigging configuration for eight-lift-point sling system using main or jib hook block with two parallel spreader bars

Figure 4.7c

Rigging configuration for eight-lift-point sling system using main or jib hook block with spreader frame

Figure 4.8a

Rigging configuration for eight-lift-point sling system using both main and jib hook blocks

Figure 4.8b

Hook load distribution for eight-lift-point sling systems using both main and jib hook blocks

Figure 5.1

Vertical Lifting of Jacket

Figure 5.2a

Horizontal Lifting of Jacket
Loadout operation at Fabrication Yard (2800ton)

Figure 5.2b

Horizontal Lifting of Jacket
Dual Crane Lifting a Tripod Jacket (6200 ton)

Figure 5.2c

Horizontal Lifting of Jacket
Dual lift of a Jacket from transportation barge

Figure 5.3

ISO View of lifting horizontal Jacket (3150ton)

Figure 6.1

Deck Panel Stacking in progress

Figure 6.2

Computer Model for Deck Panel Flip-over

Figure 6.3

Deck Panel – 180 Degree Flip Over

Figure 6.4

Module Lifting – Four Sling Arrangement

Figure 6.5

Module Installation – One Lifting Bar Arrangement

Figure 6.6

Module Lifting – Two Bars System

Figure 6.7

Module Lifting – Three Bars System

x


Figure 6.8

Lifting with a spreader frame

Figure 6.9

Multi-Tier Rigging System

Figure 6.10

Tendem Lift of a Module

Figure 7.1

Rigging arrangement for lifting FPSO modules with spreader bars

Figure 7.2

Lifting of Lower Turret (680 ton)

Figure 7.3

Lifting of Upper Turret Manifold Deck Structure with Three Spreader Bars

Figure 7.4

Lifting of Upper Turret – Gantry Structure

Figure 7.5

Lifting of Swivel Stack – Bottom Assembly

Figure 7.6

Lifting of Gas Recompression Module

Figure 7.7

Upending and Lifting of 92-metre Flare Tower

Figure 8.1

Lifting Frame Details

Figure 9.1

Computer Lifting Model Plot

Figure 9.2

COG Shift of Module during Lifting

Figure 9.3

Jacket Loadout arrangement

Figure 9.4

Upending process of Jacket

Figure 9.5

Jacket positions for the four load cases

Figure 9.6

Configuration of Joint 164

Figure 9.7

Boundary conditions for the FE model

Figure 9.8

Finite element mesh

Figure 9.9

1st-principal stress contour of load case D

Figure 9.10

Local view of Von Mises stress contour of load case D

xi


Figure A.1

Load conditions

Figure A.2

Stress distribution for the braces of load case A

Figure A.3

Stress distribution for the braces of load case B

Figure A.4

Stress distribution for the braces of load case C

Figure A.5

Stress distribution for the braces of load case D

xii


CHAPTER 1
1.1

INTRODUCTION

Background

Heavy lifts are frequently carried out during the fabrication and/or installation of major
offshore components and structures, such as welded girder beams, tubular columns,
deck panels, sub-assemblies, flares, bridges and completed jackets / modules. Without
heavy lifting equipment, offshore steel platforms cannot be built effectively.

For an offshore platform, the issue of final installation of the completed jacket /
topside is considered as early as the conceptual study stage. The major determining
factor is availability of heavy lift crane vessel around the region. Heavier structures
can be fabricated if a lager crane vessel is selected for the project. Many topside
structures are split into several modules instead of an integrated deck structure due to
non-availability of sufficient lifting capacity of heavy offshore crane barge in the
region or at required time window schedule.

Offshore hook-up and commissioning costs are very high as compared to those for the
same work performed onshore. This has led to the fabrication of very large modules,
where the intention is to minimize hook-up associated with connecting modules
together offshore.

The great advancement of offshore technology during the last 30 years was largely due
to the development of very heavy lift equipment. Thirty years ago, a 1000 ton module

would be considered a very heavy lift, while the biggest crane barge in the world at
that time could hardly lift 2000 tons at the required lifting radius. In South East Asia,
the biggest crane barge available in the region at the time was only around 600 tons.

1


Nowadays, a semi-submersible derrick barge can lift a structure up to 12,000 tons.

In the recent past, a 10,000 ton jacket in the North Sea would have to be launched.
Using present day equipment, the same jacket can now be lift-installed by a semisubmersible crane barge which has two cranes. In most cases, lift-installed jacket is
more cost-effective. In South East Asia, jackets and decks are getting larger and
heavier, with the largest jacket to-date around 10,000 tons and the largest deck around
11,500 tons. Single lift installation can be a very attractive cost alternative. For
platform decommissioning or removal, it may be possible to use a crane barge to pick
up the old deck and old jacket. It may be appropriate to mention that the Offshore
Industry would not have developed to what it is today without all the heavy lift
equipment developed over the last 30 years.

For fabrication of offshore structures, the method which was first developed in the
United States more than 40 year ago is quite different from other industries. Offshore
structures are usually first fabricated in small units. After fabrication, these will be
moved to an open area for assembly. Offshore contractors tend to do as much work as
possible on the ground to minimize work in the air. This method is productivity driven.
In fabrication, one can do a much better and faster job on the ground and in a weather
protected workshop. This fabrication technique means that there are a lot of heavy
lifting operations in the yard as compared to typical onshore building construction.
Before all the sub-units are assembled, these may need to go through many lifting
operations, such as, roll up, stacking, flipping, etc. Each lift by itself could be more
than one thousand tons. In this type of fabrication technique, there are a lot of

2


opportunities for errors. Safety and accident prevention should thus be considered in
the design stage.

For offshore installation, major cost savings can be achieved if the structure can be
installed in one piece. For integration of topside modules, it can save significant
offshore hook-up time. For jacket, the cost of fabricating launch trusses can be
eliminated. A heavier lift requires a larger crane barge. It is a very high premium to
pay for the rental of a big derrick barge, especially if none is available in the area and it
has to be mobilized from elsewhere. A large capacity crane is an expensive equipment
and crane usage is normally considered as part of the overhead cost for fabrication
yards. Usually the cost is included in the fabrication tonnage rate. It will normally
involve fewer people to operate a crane onshore. For offshore installation, a crane
barge usually has only one big crane, except for larger semi-submersible derrick
barges which can accommodate two cranes side-by-side. When a derrick crane barge is
mobilized for an offshore installation project which includes hook-up and
commissioning, it will have 200 to 300 workers/engineers on board. The cost is
extremely high. Some of the semi-submersible derrick barges have accommodation
capacity for more than 700 men. In addition, the client will also need to pay for
mobilization and demobilization costs. Depending on location, these costs could be
millions of dollars. To design a structure to suit the installation contractor is certainly
an excellent way to minimise cost.

For a typical project, the offshore portion accounts for around 30% of the total project
cost. The question that comes to everyone's mind is how to reduce this number and be
more competitive. One of the solutions is to reduce offshore hook-up time. This means

3


that one should make the lift of a structure as heavy as possible and with few lifts as
necessary. However, one should be extremely careful in interpreting this statement.
The project may not be cheap if one has to mobilize a big derrick barge from far away
supply base. It could also be expensive if it requires two barges to do the lift and the
other barge has to be mobilized from elsewhere. Making a single heavy lift to
minimize hook up time or to eliminate the launch trusses is an excellent idea provided
we have the right equipment at a reasonable price and at the right time.

For FPSO module installation, there are normally 20 to 30 heavy lifts. The need to
design a common rigging system to suit different configurations, weights and centres
of gravity is a challenge to all designers. Since it is usually impossible to have a
common rigging system for all lifts, the designer needs to minimize the number of
rigging changes to reduce the schedule associated with heavy lifts for the planned
installation sequence.

4


1.2

Objectives and Scope of Present Study

As indicated in Section 1.1, heavy lifts in major offshore projects are required to be
conducted safely and cost-effectively. It is always a challenge for a structural design
engineer to produce an optimized design for both the lifted structure and lifting rigging
system for use with the selected crane barge that will lead to cost savings. The author
has been involved in some major offshore projects which required considerations for

alternative designs and detailed analysis for different structural schemes for heavy lift.
The author is thus motivated to investigate the inter-related engineering and fabrication
issues and to document the findings in this thesis.

The two key objectives of the research study are:
•

Investigate lifting schemes which can provide cost-effective solutions and safe
operations for heavy lift installation of structures, and

•

Evaluate selected rigging systems with different spreader and lift point
arrangements to provide guidelines for heavy lift design.

The scope of the present study can be summarized as follows:
•

To study the current design codes for lift design and highlight key
considerations for heavy lift;

•

To evaluate heavy lift rigging systems which involve different crane barges and
lifted structures with associated spreader arrangement and consistent lift point
combinations. Practical issues involved in actual projects, especially for lift
installation of jackets, offshore decks and modules for FPSO (Floating
Production Storage and Offloading) vessel will be investigated.

•

To investigate global structural responses of lifted structures and detailed stress

5


conditions of the lift point through finite element analyses.
•

To document the findings on heavy lift in the thesis for future reference by
designers and engineers.

6


1.3

Organisation of Thesis

Figure 1.1 summarises the organisation and contents of the thesis.

Following the introduction, Chapter 1 and Chapter 2 provide a thorough review and
discussion of current design codes and standards used in heavy lift. The discussion
covers the codes and recommendations from API - RP2A (2000), DNV Marine
Operations Part 2 - Recommended Practice RP5 Lifting (1996), Phillips Petroleum
(1989), Heerema (1991), Noble Denton & Associates (NDA) (1996), Health and
Safety Executive (HSE) (1992) and Shell (1990).

Lifting equipment and components, including details on crane vessel/barge, slings,
shackles and lift points are discussed in Chapter 3. Lift points are the locations where

large sling tensions are transmitted to the lifted module structure. Lift points should be
properly selected to allow sling tensions to smoothly transfer to strong structural
members. Two common types of lift points which connect rigging systems to module
structures are padeyes and trunnions. With appropriate factored sling tensions, slings
and shackles can be selected from available sling and shackle lists (inventories) or
ordered from suppliers. It has always been the focus of the design codes to provide
consistent safety factors for the lift components within a rigging system for heavy lift.

An appropriate rigging system includes available lift points (strong points in the
module structure), available slings in inventory, spreader structure (bar or frame) and
hook block(s) of the crane barge. In actual rigging arrangement, the sling system can
involve four, six, eight or more lift points, and spreader bar or frame may be used to

7


protect the module from significant compressive forces or possible damage. Chapter 4
summarises the investigation into the algorithms and formulations to determine the
configurations of rigging sling systems, which are affected by the location of lift
points, length of slings and geometry of spreader and hook block. The hook block(s)
involved in a particular rigging system can be one (main or jib hook) or two (both
main and jib) at a time. Emphasis is placed on the determination of the critical
geometrical quantities of the rigging system including the sling angles with respect to
the horizontal plane and the distances between the module, spreader structure and hook
blocks. This chapter also serves as a theoretical basis of the following three chapters
which focus on practical issues in lift design of real projects, of which author was
involved as project manager or engineer.

Chapters 5, 6, and 7 discuss the practical considerations in lift design and operations
for jacket, modules and modules for FPSO (Floating Production Storage and

Offloading). A special design for a lifting frame is proposed and analyzed in Chapter
8.

Finite Element Analysis (FEA) is widely accepted in almost all engineering
disciplines. A finite element model can represent and analyse a detailed structural
component with greater precision than conventional simplified hand calculations. This
is because the actual shape, load and constraints, as well as material property can be
specified with much greater accuracy than that used in hand calculations. Chapter 9
discusses finite element approaches in heavy lift design and analysis. Two important
lift applications, for living quarter module lifting and padeye connection for heavy lift,
are investigated and reported in this chapter.

8


Finally, conclusions and general discussions are given in Chapter 10.

Evaluation of Design
Criteria

Equipment Selection and
Component Design

Rigging Theory and
Formulations

(Chapter 2)

(Chapter 3)

(Chapter 4)

Theory and Knowledge

Structures
to Be Lifted

Rigging System

Lift Points

Lift Operation

Scopes for Design and Analysis

Jacket Lifting

Lifting Frame Design

(Chapter 5)

(Chapter 8)

Module Lifting

(Chapter 6)

FEM Analysis for Lifting System

(Chapter 9)

FPSO Structure Lifting

(Chapter 7)
Applications

Figure 1.1

Special Case
Considerations

Thesis organization and contents of the thesis

9


CHAPTER 2

2.1

LIFTING CRITERIA

Review of Various Lifting Criteria

There are several lifting criteria and specifications written specifically for offshore
heavy lift, including API-RP2A (2000), DNV Marine Operation Part 2 Recommended
Practice RP5 (1996), Phillips Petroleum (1989), Heerema (1991), Noble Denton &
Associates (NDA) (1996), Health and Safety Executive UK (HSE) (1992) and Shell
(1990). Amongst these criteria, some of these are either not updated or strictly for inhouse use. Only the API, DNV and HSE codes are easily available to the general
public. The API codes are the oldest and the most well established in the Offshore
Industry. The HSE recommendation deals with cable laid slings and grommets in

detail, but it does not address other lifting system or factors such as dynamic
amplification, weight growth, etc. This recommendation should be used in conjunction
with other codes. The DNV code is the most comprehensive and is widely used in the
North Sea.

For South-East Asia, the most commonly accepted criterion is still the API-RP2A
(2000) with a number of modifications to cater for weight inaccuracy etc. The original
lifting criterion in the API RP2A (2000) was written mostly by engineers working in
the Gulf of Mexico. The document was intended for those lifts performed in the area.
Over the years, the code expanded and received acceptance as a worldwide standard.
Although these criteria are written primarily for offshore lift, they can also be adopted
for onshore lift with minor modifications. In fact, this has been done for many years.

10