TECHNICAL POLICY BOARD

SELF-ELEVATING PLATFORMS
GUIDELINES FOR ELEVATED OPERATIONS

0009/ND

Once downloaded this document becomes UNCONTROLLED.

Please check the website below for the current version.

31 Mar 10

MJRH

Technical Policy Board

16 Dec 08

MJRH

Technical Policy Board

7 Dec 07

MJRH

Technical Policy Board

25 Oct 06

MJRH

Technical Policy Board

02 Aug 06

MJRH

Technical Policy Board

12 Dec 86

JR

Technical Policy Board

DATE

REVISION

PREPARED BY

AUTHORISED BY

www.gl-nobledenton.com

GUIDELINES FOR ELEVATED OPERATIONS

PREFACE
This document has been drawn with care to address what are likely to be the main concerns based on the
experience of the GL Noble Denton organisation. This should not, however, be taken to mean that this document
deals comprehensively with all of the concerns which will need to be addressed or even, where a particular matter is
addressed, that this document sets out the definitive view of the organisation for all situations. In using this
document, it should be treated as giving guidelines for sound and prudent practice on which our advice should be
based, but guidelines should be reviewed in each particular case by the responsible person in each project to ensure
that the particular circumstances of that project are addressed in a way which is adequate and appropriate to ensure
that the overall advice given is sound and comprehensive.
Whilst great care and reasonable precaution has been taken in the preparation of this document to ensure that the
content is correct and error free, no responsibility or liability can be accepted by GL Noble Denton for any damage or
loss incurred resulting from the use of the information contained herein.

2010 Noble Denton Group Limited, who will allow:

the document to be freely reproduced,

the smallest extract to be a complete page including headers and footers but smaller extracts may be
reproduced in technical reports and papers, provided their origin is clearly referenced.

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GUIDELINES FOR ELEVATED OPERATIONS

CONTENTS
SECTION
1

2
3
4

PAGE NO.

SUMMARY
1.1
CONTENT AND SCOPE
1.2
THE APPROVAL PROCESS
1.3
ASSESSMENT FOR ELEVATED OPERATIONS
1.4
DATA TO BE SUBMITTED
INTRODUCTION
DEFINITIONS
THE APPROVAL PROCESS
4.1
GENERAL
4.2
GL NOBLE DENTON APPROVAL
4.3
CERTIFICATE OF APPROVAL
4.4
SCOPE OF WORK LEADING TO A LOCATION APPROVAL
OPERATING CONDITION
5.1
REFERENCE DOCUMENT AND DEVIATIONS THEREFROM
5.2
ENVIRONMENTAL RETURN PERIOD FOR TROPICAL REVOLVING STORM AREAS
(Revises Guideline Section 2.3.2)
5.3
MARINE GROWTH (Revises Practice Sections 3.9 and 4.7.3)
5.4
LEG INCLINATION (Revises Practice Section 5.4)
5.5
HULL SAGGING (Revises Practice Section 5.7.1 / Commentary 5.7.1)
5.6
ENVIRONMENTAL LOAD FACTOR (Revises Practice Section 8)
5.7
FOUNDATION FIXITY (Revises Practice Section 6.3.4 and Commentary Section C6.3.3/4)
5.8
OVERTURNING SAFETY FACTOR (Revises Practice Section 8.2)
5.9
BEARING CAPACITY AND RESISTANCE TO SLIDING (Revises Practice Section 8.3)
5.10
LEG AND HOLDING SYSTEM STRENGTH (Revises Practice Section 8.1 and 8.5)
5.11
OTHER CONSIDERATIONS

4
4
4
4
4
5
6
7
7
7
7
7
9
9
9
9
9
10
10
10
10
10
11
11

REFERENCES

13

APPENDIX A - DATA TO BE SUBMITTED

14

APPENDIX B - OPERATIONS MANUAL

16

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GUIDELINES FOR ELEVATED OPERATIONS

SUMMARY

1.1

CONTENT AND SCOPE

1.1.1

These guidelines will be used by GL Noble Denton for the assessment of self-elevating platforms in the
elevated condition. They address:

1.1.2
1.1.3
1.1.4

1.1.5
1.1.6
1.1.7
1.1.8
1.1.9
1.1.10

General feasibility studies, including optional checks for punch-through resistance and fatigue;
such studies may result in a Statement of Compliance.

Assessment for specific locations; such studies may result in a Certificate of Approval.
This document is intended to apply to self-elevating units of all types.
Where a unit is not Classed for elevated operations, additional requirements apply.
Revision 1 did not cover self-elevating platforms when afloat, as this is now covered by the companion
Guideline 0030, Ref [1]. The guidance for elevated operations was addressed in greater detail, and
referenced SNAME T&RB 5-5A, Ref [2].
Revision 2 of this document superseded Revision 1, with the inclusion of deviations to additional
sections of SNAME T&R Bulletin 5-5A.
Revision 3 superseded Revision 2. The principal change was a re-wording of Section 5.2.1. The
pagination was improved.
Revision 4 superseded Revision 3. The principal change was reformatting and removing references to
NDI (Noble Denton International).
This Revision 5 supersedes Revision 4 of this document. The principal change is rebranding as GL
Noble Denton.
It should be noted that this document cannot cover every case for all types of jack-up. The reader
should satisfy himself that the guidelines used are fit for purpose for the situation under consideration.
These Guidelines are not intended to exclude alternative methods, new technology and new
equipment, provided an equivalent level of safety can be demonstrated.

1.2

THE APPROVAL PROCESS

1.2.1

A description of the Approval Process is included, for projects where GL Noble Denton is acting as a
Warranty Surveyor. The extent and limitations of the approval given are discussed.

1.3

ASSESSMENT FOR ELEVATED OPERATIONS

1.3.1

Guidelines are presented for the assessment of elevated operations. Subject to the specific variations
and additions set forth herein this document refers to the SNAME T&R5-5A for the data requirements,
calculation methodology and acceptance criteria to be applied.

1.4

DATA TO BE SUBMITTED

1.4.1

The data to be submitted is summarised in the Appendices.

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GUIDELINES FOR ELEVATED OPERATIONS

INTRODUCTION

2.1

This document provides guidelines for the operation of self elevating platforms (jack-ups). It refers to
engineering studies that are complementary to inspection of the unit and the acquisition of applicable
site data, refer to 0016/ND Seabed and Sub-Seabed Data Required for Approvals of Mobile Offshore
Units (MOU), Ref [3]. The towage and transportation of jack-ups is addressed in the GL Noble Denton
Guideline Guidelines for Marine Transportations 0030/ND, Ref [1].

2.2

Where approval by GL Noble Denton is required, sufficient information should be submitted by the
client in order to allow confirmation that the unit meets the criteria.

2.3

These guidelines are intended to cover the structural design and site specific assessment of the unit.
However, the sea bed conditions and the structural design or assessment of the unit are closely interrelated, so references to sea bed conditions are made in this report. Any approval for operations
indicated by compliance with these guidelines is subject to the sea bed conditions, and the normal
marine and operational recommendations of GL Noble Denton offices.

2.4

Revision 1 of these guidelines dated 02 August 2006 superseded those contained in Revision 0 of this
document dated 12 December 1986. The principal changes and revisions were:

2.5

Deletion of sections referencing towage and transportation.

Reference to SNAME T&R Bulletin 5-5A as the basis for the assessment of elevated
operations, subject to the deviations as set out herein.

Revision 2 superseded the guidelines contained in Revision 1 of this document dated 02 August 2006.
The principal revisions are the inclusion of deviations to the following additional sections of SNAME
T&R Bulletin 5-5A:

3.9 Marine Growth;

5.4 Leg Inclination;

5.7.1 / C5.7.1 Hull sag.

2.6

Revision 3 superseded Revision 2. The principal change was a re-wording of Section 5.2.1. The
pagination was improved.

2.7

Revision 4 superseded Revision 3 of this document. The principal change is reformatting and
removing references to NDI (Noble Denton International).

2.8

This Revision 5 supersedes Revision 4 of this document. The principal change is rebranding as GL
Noble Denton.

2.9

These guidelines are intended to lead to an approval by GL Noble Denton. Such approval does not
imply that approval would be given by designers, regulatory bodies, harbour authorities and/or any
other party.

2.10

All GL Noble Denton Guidelines can be downloaded from www.gl-nobledenton.com.

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GUIDELINES FOR ELEVATED OPERATIONS

DEFINITIONS

3.1

Referenced definitions are underlined.

Term or Acronym

Definition

API

American Petroleum Institute

Assured

The Assured is the person who has been insured by some insurance
company, or underwriter, against losses or perils mentioned in the policy
of insurance.

Assessment
environmental condition

The metocean conditions applicable to the site specific assessment.

Either the 50-year individual extremes or the 100 year joint probability
values. Directionality and seasonality may be used where applicable.

Assessment significant
wave height

Either the 50-year individual extreme significant wave height, or the 100
year joint probability significant wave height for the season of the
particular operation.

Certificate of Approval

A formal document issued by GL Noble Denton stating that, in its

judgement and opinion, all reasonable checks, preparations and
precautions have been taken to keep risks within acceptable limits, and
an operation may proceed.

Class

A system of ensuring floating vessels are built and maintained in

accordance with the Rules of a particular Classification Society. Although
not an absolute legal requirement the advantages (especially as regards
insurance) mean that almost all vessels are maintained in Class.

GL Noble Denton

Any company within the GL Noble Denton Group including any

associated company which carries out the scope of work and issues a
Certificate of Approval, or provides advice, recommendations or designs
as a consultancy service.

Independent leg jackup

A jack-up where the legs may be raised or lowered independently of each

other.

Insurance Warranty

A clause in the insurance policy for a particular venture, requiring the

approval of a marine operation by a specified independent survey house.

Jack-up

A self-elevating MODU, MOU or similar, equipped with legs and jacking

systems capable of lifting the hull clear of the water.

Mat-supported jack-up

A jack-up which is supported in the operating mode on a mat structure,

into which the legs are connected and which therefore may not be raised
or lowered independently of each other.

MODU

See MOU

MOU

Mobile Offshore Unit. For the purposes of this document, the term may
include mobile offshore drilling units (MODUs), and non-drilling mobile
units such as accommodation, construction, lifting or production units

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GUIDELINES FOR ELEVATED OPERATIONS

THE APPROVAL PROCESS

4.1

GENERAL

4.1.1

GL Noble Denton may act as a Warranty Surveyor, giving Approval to a particular operation, or as a
Consultant, providing advice, recommendations, calculations and/or designs as part of the Scope of
Work. These functions are not necessarily mutually exclusive.

4.2

GL NOBLE DENTON APPROVAL

4.2.1

By GL Noble Denton is meant any company within the GL Noble Denton Group including any
associated company which carries out the scope of work and issues a Certificate of Approval.
GL Noble Denton approval may be sought where the operation is the subject of an Insurance
Warranty, or where an independent third party review is required.
An Insurance Warranty is a clause in the insurance policy for a particular venture, requiring the
approval of a marine operation by a specified independent survey house. The requirement is normally
satisfied by the issue of a Certificate of Approval. Responsibility for interpreting the terms of the
Warranty so that an appropriate Scope of Work can be defined rests with the Assured.

4.2.2
4.2.3

4.3

CERTIFICATE OF APPROVAL

4.3.1
4.3.2

The deliverable of the approval process will generally be a Certificate of Approval.

The Certificate of Approval is the formal document issued by GL Noble Denton when, in its judgement
and opinion, all reasonable checks, preparations and precautions have been taken to keep risks within
acceptable limits, and an operation may proceed.
A location approval Certificate will normally be issued by the approving office well in advance of the
move to the location.

4.3.3

4.4

SCOPE OF WORK LEADING TO A LOCATION APPROVAL

4.4.1

CERTIFICATE OF APPROVAL

4.4.1.1

In order to issue a Certificate of Approval, GL Noble Denton will typically require to consider, as
applicable, the following topics:

Site-specific environmental data

Site-specific geotechnical data

Seabed survey

Previous jack-up installations

Adjacent structures

Rig capability:

Overturning Stability

Foundation capacity (bearing/sliding)

Leg strength

Holding system strength.

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GUIDELINES FOR ELEVATED OPERATIONS

4.4.1.2

Fatigue damage is excluded from any GL Noble Denton approval, unless specific instructions are
received from the client to include it in the scope of work or the unit will not be Classed by an IACS
member body for elevated operations during the planned period on location.

4.4.2

STATEMENT OF COMPLIANCE

4.4.2.1

In cases where GL Noble Denton is requested to study the general feasibility of a unit a Statement of
Compliance would be issued. The scope would typically encompass one or more of the following
topics:

Rig capability elevated (based on pinned footings or assumed soil(s) condition(s). These may
be to the criteria set out herein and/or other criteria such as Class requirements, SNAME T&R
Bulletin 5-5A, etc.
Note:

Whilst a unit may be shown to comply with Class requirements, these may not be
sufficient for the unit to be approved by GL Noble Denton
Limitations for going on and off location.

Stability afloat.*

Leg strength afloat.*

Dry transportation feasibility.*

Towing equipment and recommendations.*

Fatigue.

Accidental scenarios such as punch-through, vessel impact, etc.

* These topics are addressed in the GL Noble Denton Guidelines for Marine Transportations
0030/ND.

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GUIDELINES FOR ELEVATED OPERATIONS

OPERATING CONDITION

5.1

REFERENCE DOCUMENT AND DEVIATIONS THEREFROM

5.1.1

The calculations to assess the elevated operational suitability of a jack-up shall be carried out in
accordance with the current revision of SNAME T&R Bulletin 5-5A, Ref [2], (which comprises a
Guideline, Recommended Practice and Commentary).
Specific deviations from the requirements of SNAME are as follows.

5.1.2

5.2

ENVIRONMENTAL RETURN PERIOD FOR TROPICAL REVOLVING STORM AREAS

(Revises Guideline Section 2.3.2)

5.2.1

50-year return period individual maximum extremes shall be considered unless the unit is to operate
under conditions in which it will be unmanned or de-manned. In such cases an agreed lower return
period, typically 10-years, may be used if ALL of the following conditions apply:
a.
The unit is operating in a tropical revolving storm area.

5.2.2

b.

A proven storm warning system is in operation which gives an expected 3 days' notice of
tropical revolving storms which may pass within 200 nautical miles of the location.

c.

Support systems are in existence to evacuate all personnel prior to arrival of the storm, bearing
in mind the requirements of other platforms affected.

d.

All personnel are evacuated prior to the arrival of the storm, having rendered the well safe and
placed the rig in storm survival mode.

e.

Such evacuation procedures are contained in the operations manual, and are communicated to
all personnel aboard.

f.

Where the unit is the subject of an approval by GL Noble Denton for insurance purposes, the
limitations of the unit are disclosed to underwriters and operators.

Notwithstanding the above:

a.
The air gap shall equal or exceed the value required for 50 year return period conditions.
b.

The unit shall be capable of sustaining, to SNAME limits as modified by this Guideline, non
tropical revolving storms with a 50-year return period and tropical revolving storms that may
arise too rapidly for evacuation to be take place (in the Gulf of Mexico, these would be termed
sudden hurricanes).

5.3

MARINE GROWTH (Revises Practice Sections 3.9 and 4.7.3)

5.3.1

For short term operations, marine growth may be ignored unless required by the client or known to preexist (the SNAME Rev 2 default value is 12.5mm on radius). For the avoidance of doubt, the leg
should nevertheless be considered rough below MWL + 2.0m.

5.4

LEG INCLINATION (Revises Practice Section 5.4)

5.4.1

The effects of leg inclination may be ignored, unless there are specific reasons for it to exist (the
SNAME Rev 2 default value is 0.5% of leg length, and it is normally taken into account by increasing
the lower guide moment of each leg by the leg inclination offset multiplied by the factored footing
reaction of that leg).

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GUIDELINES FOR ELEVATED OPERATIONS

5.5

HULL SAGGING (Revises Practice Section 5.7.1 / Commentary 5.7.1)

5.5.1

The effects of hull sagging may be ignored, unless there are specific reasons for it to be included.
(The SNAME Rev 2 default value from the commentary is 25-50% of the theoretical maximum). Given
normal guide clearances and operating procedures we consider that the hull sag moments carried by
the legs will normally be negligible.

5.6

ENVIRONMENTAL LOAD FACTOR (Revises Practice Section 8)

5.6.1

Unless otherwise specified by the client, the environmental load factor may be reduced to 1.0 (from the
SNAME Rev 2 value of 1.15).

5.7

FOUNDATION FIXITY (Revises Practice Section 6.3.4 and Commentary Section C6.3.3/4)

5.7.1

Use the Noble Denton/Oxford University recommendations prepared for IADC.

Calibration of SNAME Spudcan Fixity Equations With Field Data, Ref [4].

5.8

OVERTURNING SAFETY FACTOR (Revises Practice Section 8.2)

5.8.1

For independent leg units, overturning safety factor is to be computed as:

IADC The

Factored Righting moment

Unfactored Overturning moment

5.8.2
5.8.3

The resistance factor for the righting moment shall be no larger than 0.909 (giving a factor of safety of
1.1).
For mat supported units the reaction point shall be assumed to be at the underside of the mat bottom
plating.
For mat supported units, the positive downward gravity loading on the mat shall be sufficient to
withstand the overturning moment for the 50-year loading without the loss of positive bearing on any
part of the mat.

5.9

BEARING CAPACITY AND RESISTANCE TO SLIDING (Revises Practice Section 8.3)

5.9.1

The combinations of vertical and horizontal load shall be checked against a bearing capacity envelope.
The resistance factor may be taken as 1.0 when the load-penetration curve indicates significant
additional capacity for acceptable levels of additional settlement. Settlement exceeding the operations
manual limits may be acceptable provided that:
(i) the structure can withstand the storm loading together with the effects of the inclination,
(ii)

the lateral deflections will not result contact with adjacent structures and/or impairment of the well
and

(iii) the unit is expected to be jackable afterwards.

5.9.2

5.9.3

In locations where this is not the case, or where punch-through is a possibility a resistance factor no
greater than 0.67 shall be applied (safety factor 1.5). This is to guard against abnormal events i.e.
environmental loads with a return period typically in the order of 1,000 to 10,000 years.
NOTE: The above implicitly checks that the preload is adequate.
Mat supported units shall be demonstrated to have a factor of safety against sliding of not less than 1.0
for the 50-year storm condition. The bearing/overturning capacity shall also be checked. Where these
checks indicate that the unit may move then limits for de-manning shall be established and the
requirements of Sections 5.2.1.b) - f) and 5.2.2.a) shall be followed.

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GUIDELINES FOR ELEVATED OPERATIONS

5.10

LEG AND HOLDING SYSTEM STRENGTH (Revises Practice Section 8.1 and 8.5)

5.10.1

In the absence of more stringent requirements from the client, the leg and holding system shall be
checked as follows:
Stress levels computed for 50-year storm loadings shall not exceed the yield stress of the material,
accounting for buckling where appropriate e.g. by using the AISC ASD formulations (Ref [5]), but with
all safety factors removed. Alternatively, the SNAME LRFD methods may be considered using the
resistance factors stipulated by SNAME.
NOTE: The intent is to prevent damage or deformation severe enough to prevent jacking the unit into
the water and towage to a safe location.

5.11

OTHER CONSIDERATIONS

5.11.1

RESISTANCE TO PUNCH-THROUGH
When it is desired to evaluate the resistance of a unit to punch-through the legs of independent leg,
three-legged units, shall be shown not to be loaded beyond the yield stress of the material, accounting
for buckling where appropriate when the unit suffers a punch-through during preloading under the
following conditions:a.
The rig is carrying the maximum allowable variable load for jacking operations;
b.

Maximum allowable preload water for the variable load in (a) above is on board;

c.

Leg length below the hull for this calculation shall be the sum of :- Maximum allowable water depth including tidal rise, or any lesser water depth, plus
- Maximum final penetration allowable at the water depth, up to a maximum of 30 metres,
plus:

d.

- 2 metres.
A sudden increased penetration of any one leg has occurred such that the hull takes an
inclination to the horizontal of 5 degrees, or the additional penetration equals 4 metres,
whichever is the lesser.

e.

Hull buoyancy may be taken into account in the calculation, assuming an initial airgap of 2.0m.

f.

For specific cases site- and operation-specific parameters may be taken into account e.g.
positive buoyancy and leg-by-leg preloading.

The analysis shall consider two cases:

1)
where the distance between the legs at the seabed remains constant (all three legs carry
approximately equal shear and moment) and
2)
5.11.2

where the punch-through leg penetrates vertically such that the leg separation increases and
the up-hill legs carry increased shear and moment.

EARTHQUAKE AREAS
Operations in areas subject to seismic activity may need special consideration, and a study of
earthquake loadings shall be carried out where appropriate.

5.11.3

ICE AREAS
Operations in areas affected by fast- or sea-ice are not covered by this report, and would require
special consideration.
The effects of ice accretion should be taken into account in the loadings on the structure.

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GUIDELINES FOR ELEVATED OPERATIONS

5.11.4

FATIGUE
When:
1)
Required by the client (see 4.4.1) or;
2)

The unit will not be Classed by an IACS member body for elevated operations during the
planned period on location;

the effects of fatigue on structural areas subject to continuous cyclic loading, such as the leg to
spudcan or leg to mat connection, shall be considered. Where such a unit is intended to operate for a
long period in water depths such that the same leg sections are within or near the guides, the effects of
fatigue on the legs near the guides and splash zone shall also be considered.

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GUIDELINES FOR ELEVATED OPERATIONS

REFERENCES
[1]

GL Noble Denton document 0030/ND - Guideline for Marine Transportations

[2]

SNAME Technical and Research Bulletin 5-5A, latest revision, Site Specific Assessment of Mobile Jack-Up
Units.

[3]

GL Noble Denton document 0016/ND - Seabed and sub-seabed data required for approvals of Mobile
Offshore Units (MOU)

[4]

IADC The Calibration of SNAME Spudcan Fixity Equations With Field Data, Noble Denton Europe Report
No: L19073/NDE/MJRH, Rev 4, Dated 21st November 2005, Prepared for IADC in association with Prof G.T.
Houlsby and Dr M.J. Cassidy, Department of Engineering Science, Oxford University

[5]

AISC Allowable Stress Design and Plastic Design, July 1, 1989, with Supplement 1

All GL Noble Denton Guidelines can be downloaded from www.gl-nobledenton.com

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GUIDELINES FOR ELEVATED OPERATIONS

APPENDIX A - DATA TO BE SUBMITTED

A.1

DRAWINGS AND TECHNICAL INFORMATION

A.1.1

For any generalised approval in principle, the following information should be submitted to GL Noble
Denton:
Designers general specifications for unit

A.1.2

Current Operations Manual (see Appendix B) if available. If not available, details of fixed and
moveable hull light weights, leg and footing weights, variable load to be considered and individual and
combined CoGs. These details to include weights and centres of gravity for:

Hull
Fixed Load (machinery and outfitting)
Moveable Load (Cantilever, substructure, derrick and draw-works)
Legs
Spudcans and can water (or mat and ballast as appropriate)
Maximum allowable variable load for elevating, lowering, operating, survival
Maximum preload that can be applied to each leg through the elevating system. Where
applicable values for regular and leg-by-leg preloading should be provided.

A.1.3

General arrangement plans and elevations showing the hull, jackhouses, accommodation, etc., and
deck mounted equipment.

A.1.4

Leg structural drawings.

A.1.5

Spudcan arrangements and structure.

A.1.6

Details of significant leg and/or hull appurtenances e.g., raw water structures and their guides.

A.1.7

Jackhouse or jack frame structure, showing connection into hull.

A.1.8

Upper and lower guide structural drawings.

A.1.9

Jacking and holding system arrangements and specifications and principles of operation, including:

A.1.10

Stiffness of jacks and, where fitted, holding system,

Jack capacities for elevating, lowering, preloading, and the basis on which these are quoted,

Jack system ultimate capacity and where applicable jack slip load,

Holding system ultimate capacity.

Hull drawings showing scantlings of the decks, bulkheads and framing.

A.1.11

If not described in the Operations Manual (see Appendix B), or this is not available, Tank
arrangements including capacities and positions or total preload and CoG, associated variable load &
CoG, Lightship CoG, Preloading details/procedure and limiting feature e.g. tank capacity, elevating
system or spudcan/mat bearing pressure.

A.1.12

Hydrostatic and stability information

A.1.13

Material specifications.

A.1.14

Area and season of operation, or water depth, wave height, current speed and wind speed
combinations for which approval is required.

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GUIDELINES FOR ELEVATED OPERATIONS

A.2

SITE SPECIFIC INFORMATION

A.2.1

For the assessment or approval of the unit and its foundation at a specific location the following
information should additionally be submitted to GL Noble Denton:
Location name/designation and coordinates.

A.2.2

Water depth with Datum.

A.2.3

Geotechnical data.

A.2.4

Proposed airgap (if other than minimum safe).

A.2.5

Proposed rig heading.

A.2.6

Proposed season for operations.

A.2.7

Details of any intended deviations from the operations manual e.g. revised variable load and/or CoG,
revised windage due to deck equipment, support of more than one conductor, etc.

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GUIDELINES FOR ELEVATED OPERATIONS

APPENDIX B - OPERATIONS MANUAL

B.1

B.1.1

A copy of the Operations Manual should be submitted to GL Noble Denton for information. This should
contain all information relevant to the safety of the unit, personnel and major items of equipment on
board the unit, including but not limited to:
General specification, setting out limitations on operating water depths and corresponding
environmental conditions

B.1.2

General arrangement plans and elevations

B.1.3

Compartmentation and piping systems

B.1.4

Weights and centres of gravity of hull and equipment, skid unit, legs and spudcans

B.1.5

Loading instructions, giving limitations on weight and centre of gravity, with worked examples of
loading calculations for elevated and afloat conditions

B.1.6

Details of jacking system, stating maximum elevating, lowering and holding loads and all necessary
checks before jacking operations, including where applicable the required torque and brake clearance
for each motor

B.1.7

Variable load capacities

B.1.8

Tank calibration tables

B.1.9

Details of propulsion units (if any)

B.1.10

Details of critical downflooding openings, means of closure, and instructions for ensuring closed under
tow

B.1.11

Limitations for going on and off location

B.1.12

Critical motion curves for towage for relevant leg lengths and positions

B.1.13

Preloading instructions

B.1.14

Maximum and minimum permitted penetration, and reasons for any restrictions

B.1.15

Instructions for filling and emptying spudcans

B.1.16

Jetting system layout and operation

B.1.17

Maintenance schedules for machinery and systems. Inspection schedules for structure

B.1.18

Reference to more detailed manuals for machinery and systems

B.1.19

Allowable loadings and positions of cantilever and substructure for operating and survival conditions.

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