RISER AND I-TUBE CLAMP INSTALLATION

PROCEDURE

VML-VMML Doc. No. : C1004-PR-U-003

Client : ONGC

Project : B-46 SERIES AND N15 & N16 PIPELINES PROJECT

Client Contract No. : MR/OW/MM/B-46/PL/04/2010

VMML Contract No. : C10-04

Date: 18.8.2011
Rev.: 0

CONSORTIUM OF VALENTINE MARITIME LTD. &

VALENTINE MARITIME (MAURITIUS) LTD
 CONSORTIUM OF
VALENTINE MARITIME LIMITED & VALENTINE
MARITIME MAURITIUS LIMITED
RISER AND I-TUBE CLAMP INSTALLATION
PROCEDURE

VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 1 of 11

REVISION CONTROL SHEET

REV. DATE PAGE NO. DESCRIPTION

0 18.8.2011 Issued For Information
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MARITIME MAURITIUS LIMITED
RISER AND I-TUBE CLAMP INSTALLATION
PROCEDURE

VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 2 of 11

TABLE OF CONTENTS
1.  INTRODUCTION ............................................................................................................................................... 3 
1.1  General...................................................................................................................................................... 3 
2.  REFERENCES, DEFINITIONS AND ABBREVIATIONS.................................................................................. 5 
2.1  REFERENCES .......................................................................................................................................... 5 
2.1.1  General Documents .................................................................................................................................. 5 
2.1.2  Company Specifications, Codes and Standards................................................................................... 5 
2.1.3  Project Documents .................................................................................................................................... 5 
2.2  DEFINITIONS ............................................................................................................................................ 5 
2.3  ABBREVIATIONS ..................................................................................................................................... 5 
3.  RESPONSIBILITY ............................................................................................................................................. 6 
3.1  BARGE SUPERINTENDENT .................................................................................................................... 6 
3.2  CHIEF ENGINEER .................................................................................................................................... 6 
3.3  FIELD ENGINEER..................................................................................................................................... 6 
3.4  BARGE FOREMAN................................................................................................................................... 6 
3.5  ANCHOR FOREMAN ................................................................................................................................ 7 
3.6  HSE OFFICER ........................................................................................................................................... 7 
3.7  Diving Supervisor .................................................................................................................................... 7 
4.  DESCRIPTION .................................................................................................................................................. 8 
4.1  Pre-installation checks............................................................................................................................ 8 
4.2  MARKING CLAMPS POSITIONS ........................................................................................................... 10 
4.3  REMOVAL OF ANODES & MARINE GROWTH .................................................................................... 10 
4.4  INSTALLATION OF CLAMPS ................................................................................................................ 10 
4.5  ALIGNMENT CHECK OF RISER/I-TUBE CLAMPS .............................................................................. 11 
4.6  INSTALLATION OF HANG-Off CLAMP ................................................................................................ 11 

APPENDIX-A: DESIGN AND INSTALLATION DRAWINGS A

APPENDIX-B: GUIDELINES FOR CLAMP INSTALLATION AT SOME SELECTED PLATFORMS B
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 3 of 11

1. INTRODUCTION

1.1 General

Oil and Natural Gas Corporation Limited, herein after, called as ‘Company’ is engaged in exploration &
exploitation of Mumbai High Field located about 160 km. West-North-West of Mumbai and Bassein Field
located about 80 km West-North West of Mumbai which are in the Arabian Sea on the continental shelf of
Western India. The fields are well developed, with an extensive infrastructure of wellhead platforms,
process platforms and pipelines.

B46-SERIES GAS FIELDS DEVELOPMENT

The fields B-46, B-48, B-105 and B-188 are small gas fields located at about 40 Km N-W of Mumbai High
field. The gas from B-46 & B-48 well is sweet whereas the gas from B-105 & B-188 well platforms is sour.
The transportation path has been worked out that would involve laying of flow lines from B-105 & B-188 to
B-48 and from B-48 to B-46 platform for B46 series field gas and further transportation of this gas to new
upcoming MNP Platform.

N-15 & N-16 PLATFORMS

N-15 & N-16 in Mumbai High North Field are 12 slots, SMART type unmanned Well Head platforms. Well
fluid from N–15 and N–16 will be routed to upcoming MNP Process Platform. Lift gas and injection water
shall be routed from various platforms.

ONGCL, Client has awarded the B-SERIES AND N-15 & N-16 PIPELINE PROJECT to VML-VMML
Consortium. The said project has been awarded as an EPC Contract with a scope of work appended below:

a. PIPE LAYING:
TOTAL LENGTH OF PIPELINE TO BE LAID IS 106.19 KM WHICH CONSISTS OF 14 SEGMENTS OF
PIPE LINES AS DETAILED BELOW:
• Five (5) nos. Gas Lift Lines out of which 3 line are rigid (MNP - N15, N15- N14, NV- N16), & the
balance 2 lines are flexible (N3 -WI2 & N1-WI5).
• Eight (8) nos. Well Fluid Lines (B188-B48, B105-B48, B48-B46, B46-MNP, N15-MNP, N16-MNP,
WI2-N3 & WI5-N1) – Rigid.
• One (1) no. Water Injection Line (N14- N18) – Flexible.

b. TIE-INS:
• Hook-up of Pipelines @ Process/ Well Platforms (either with the pre-installed risers, or the ones to
be installed by contractor during this project)
• Total tie-ins = 17 nos.

c. RISERS:
• Five (5) nos. Risers at NV, N1, N3, WI-2 & WI-5 Platforms.

d. I/J TUBES:
• Six (6) nos. I/J tubes to be installed at N14, N18, N1, N3, WI-2 & WI-5 Platforms.

e. TOPSIDE MODIFICATIONS:
• TOPSIDE MODIFICATION OF EXISTING WELL PLATFORM NV & NW.
• Installation of Lift gas launcher, associated piping & instrumentation, new stand-alone pneumatic
shutdown panel & extension of existing fire water sprinkler network, etc…
• Procurement of loose items for NV & NW Platforms.
• Hook ups at N14, N18, N1, N3, WI-2 & WI-5 platforms topside.
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 4 of 11

f. B-SERIES AND N-15 & N-16 P/L Project has the following completion dates (as defined in NOA):
SCHEDULED COMPLETION
1) Segments: Completion Date :10.03.2012
• B-48 to B-46.
• B-46 to MNP.
2) Segments:
• B-188 to B-48 Completion Date: :10.04.2012
• B-105 to B-48.
3) Segments:
• N-15 to MNP. Completion Date: 15.05.2011
• N-16 to MNP.
• MNP to N-15.
• N-15 to N-14 (GL).
• NV to N-16.
• N-14 to N-18.
• WI-2 to N-3 (WF)
• WI-5 to N-1 (WF)
• N-3 to WI-2 (GL)
• N-1 to WI-5 (GL)
• Associated top side Modification at NV Platform.
4) Completion of Project in all respects Completion Date: 15.05.2011
(including handing over of loose materials for NV & NW)

i. Rigid Pipeline Data

Pipeline W.D. Pipe Pipe Pipe Grade P/L CTE CWC

Sr Segment (m) OD W.Th CS Length Thk D* Thk**
# (mm) (mm) (kM) (mm) kg/m
3
(mm)
1 B105-B48 75.3 273.1 14.3 X-60 - “Nace” 10.300 4.75 3044 30
2 B188-B48 78.2 219.1 12.7 X-60 - “Nace” 10.052 4.75 3044 30
3 B48-B46 77.5 355.6 15.9 X-60 - “Nace” 11.888 4.75 3044 30
4 B46-MNP 74.7 406.4 17.5 X-60 - “Nace” 19.111 4.75 3044 30
5 N15-MNP 71.4 323.9 14.3 X-60 - “Nace” 6.485 4.75 3044 60 , 30
6 N16-MNP 71.4 323.9 14.3 X-60 - “Nace” 5.929 4.75 3044 60 , 30
7 MNP- N15 71.4 323.9 12.7 X-60 - “Nace” 6.587 4.75 3044 40
8 N15-N14 (GL) 60.1 323.9 12.7 X-60 - “Nace” 7.090 4.75 3044 50
9 NV-N16 73 168.3 7.9 X-60 - “Nace” 4.196 4.75 3044 30
10 WI2-N3 (WF) 80 323.9 14.3 X-60 – “Non-Nace” 4.000 4.75 3044 TBA
11 WI5-N1 (WF) 80 323.9 14.3 X-60 – “Non-Nace” 4.000 4.75 3044 TBA
*D : Density. ** Thk: Thickness of Concrete Weight Coating.
ii. Flexible Pipelines Data
S/N Pipeline Segment W. Depth (m) Pipe ID (mm) Pipeline Length (km)
12 N14-N18 52.6 - 55.9 203 6.607
13 N3- WI2 (GL) 80 152 4.000
14 N1-WI5 (GL) 80 152 3.200
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 5 of 11

2. REFERENCES, DEFINITIONS AND ABBREVIATIONS

2.1 REFERENCES

2.1.1 General Documents

MR/OW/MM/B-46/PL/04/2010 B-SERIES AND N-15 & N-16 PIPELINE PROJECT
2.1.2 Company Specifications, Codes and Standards
Functional Specifications For Installation of Submarine Pipeline
ONGC Spec. No. 2015
And Related Facilities

2.1.3 Project Documents

C1004-PR-L-003 Pipeline Startup, laying & laydown procedure
Rigid Pipeline Flooding, cleaning, gauging & hydrotesting
C1004-PR-L-007
procedure
C1004-PR-L-010 Subsea Tie-in spools & Bolt tensioning installation procedure
C1004-PR-L-012 Crossing & Free span correction procedure
C1004-PR-U-001 Risers & Riser Clamps installation procedure

2.2 DEFINITIONS
Company/Client ONGCL
Contractor VML-VMML Consortium
Sub-Contractor Dunnimaa
Vendor Any organization selected & awarded by VMSL to supply Project Material
and/or Equipment.

2.3 ABBREVIATIONS
HSE Health, Safety and Environment
KP Kilometer Point
PPE Personnel Protective Equipment
TBA To Be Advised
VML-VMML Valentine Maritime Limited - Valentine Maritime (Mauritius) Limited.
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 6 of 11

3. RESPONSIBILITY
This procedure shall be followed by all concerned onboard all marine units involved in Field Joint Coating
Operations. Specific responsibilities are as follows:

3.1 BARGE SUPERINTENDENT

The Barge Superintendent is responsible for the following activities:
a. Responsible for Barge movement in the field after obtaining necessary permits.
b. Responsible for implementation of Barge Management Manual.
c. Responsible for implementation of Company Quality & HSE requirement to ensure that all
personnel onboard follow Quality & HSE requirements.
d. Monitoring of progress of Barge Project Scope of Work.
e. Ensuring that all supervisory personnel have attended a project familiarization and HSE briefing
prior to commencement of works.
f. Coordination with the Clients, Manager Operation and Field Engineer for smooth execution of
project.

3.2 CHIEF ENGINEER

The Chief Engineer is responsible for the following activities:
a. Overall in-charge of the engine room department and all equipment ensuring that they are made
available in good condition.
b. Reporting to the Barge Superintendent and Company Management about the status of all
equipment on the work barge, their up keep & overall function of the department and associated
marine units.
c. Ensure periodic maintenance and availability of spares & consumables mainly for equipment and
machinery.
d. Planning and scheduling all technical crew activities for the up-keep of the barge and equipment.

3.3 FIELD ENGINEER

The Field Engineer is responsible for the following activities:
a. Liaising with shore base, Barge management and Company representatives to ensure that the
requirements of Company Specifications and Contract are followed while executing each activity.
b. Completion of onsite technical queries and operational requests as required.
c. Ensure that operation is done in accordance with relevant procedure documents and standards
d. In-charge of providing construction engineering to construction crew, explaining and highlighting the
requirements in the drawings deemed to be unclear or uncommon.
e. Prepare and obtain from client, approval of the Daily Progress Report and carry out other daily
correspondences.
f. Ensure relevant work permits are obtained.

3.4 BARGE FOREMAN

The Barge Foreman reports directly to the Barge Superintendent. Responsibilities include:
a. Ensuring that all tasks are carried out in a safe and efficient manner during his shift.
b. Ensure safe and proper operation of equipment during his shift, especially the barge crane, Winches
etc.
c. Maintaining proper housekeeping & general maintenance of the barge deck
d. Implement and follow permit to work system onboard.
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RISER AND I-TUBE CLAMP INSTALLATION
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 7 of 11

3.5 ANCHOR FOREMAN

The Anchor Foreman reports directly to the Barge Forman. Responsibilities include:
a. Preparing anchors, buoys, pendant wires, D.P. buoys during Barge mobilization.
b. Checking the Barge mooring systems (anchor winches / anchor wires) & reporting to Barge
Foreman.
c. Movement of the Barge on its anchors by running anchors & assisting tower operations.
d. Planning & plotting anchor positions as per approved Anchor Pattern.
e. Monitoring and control of anchor buoys & pendant wires and anchors, during barge operations.
f. To co-ordinate with AHT and Surveyor to deploy Anchors.

3.6 HSE OFFICER

a. Provide precautions and warnings on HSE matters to the barge crew relating to Anchor Handling.
b. Periodic HSE inspection of equipment before operational use.
c. Distribution and control of all operations reference books, safety notices and technical data
affecting HSE on board the Barge.
d. Establishment and maintenance of effective emergency procedures.
e. Identify hazards at worksites and suggest preventive measures.
f. Ensure that the PPE is fit for the purpose & to standards and adequate.
g. Ensure that environmental guidelines on the project are adhered to.
h. Ensure proper waste management procedures are followed.
i. Investigate all near misses and accidents and suggest corrective actions to prevent re-occurrence.
j. Collect and compile HSE data and communicate findings to the VML management.
k. Assist in conducting risk assessments on board.
l. Provide topics for toolbox talks and monitor/ record the same.
m. Prepare and obtain from client relevant work permits (if applicable).

3.7 Diving Supervisor

a. Responsible for the safe implementation and completion of the work program within the constraints
of current legislation and Company Procedures.
b. Ensure that all the diving plant and equipment is tested, maintained and repaired in accordance
with statutory requirements.
c. Fully brief the diver(s) to each dive and assist the field engineers in the preparation of Dive Plans.
d. Ensure that the plant and equipment being used meets all regulatory requirements.
e. Ensure that dive communication recordings are of acceptable quality.
f. Confirm that all divers are fit to dive prior to the immediate commencement of surface operations.
g. Ensure that he does not dive while he is acting Supervisor.
h. On completion of the project, the Diving Supervisor shall, assist in the preparation of the final
report.
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 8 of 11

4. DESCRIPTION
4.1 Pre-installation checks
a) The standoff distance for the “hanger” and “fixed” clamps has to be checked on deck by measuring
the distance between the centre of brace clamp and the centre of the riser/I-tube clamp.
This distance is referred to as “K” in the drawings. The value of “K” is provided in series of drawings
showing the location of riser/I-tube and riser/I-tube clamps (see Appendix A).
All the measurements of “K” should be verified on deck and passed to the field engineer to compare
and check the variations with the drawings; and if variations are found, the decision might be taken
to modify clamps prior to any installation commencement.
b) Internal diameter of brace clamp should be measured and compared with the jacket braces
diameter (TABLE 1) to make sure there is no variation.
c) Diameter of riser/I-tube clamp should be measured and compared with riser/I-tube outer diameter
to make sure there is no variation
d) Testing bolts and nuts threads.
e) Any obstructions underwater, like for instance anodes, should be removed temporarily and then re-
instated afterwards.

TABLE NO. 1 RISER CLAMPS

Elevation OD of brace
Jacket Clamp No/type
(m) clamp
NV-HC-A1 + 6.700 660
NV-AC-A2 + 1.600 610
NV-AC-A3 - 1.765 610
NV-FC-A4 - 9.463 610
NV-AC-A5 - 20.000 508
NV
NV-FC-A6 - 28.603 660
NV-FC-A7 - 35.000 610
NV-FC-A8 - 42.950 406
NV-AC-A9 - 52.000 660
NV-AC-A10 - 57.193 508
N3-HC-A1 + 6.700 660
N3-AC-A2 + 2.700 610
N3-FC-A3 - 8.000 508
N3
N3-FC-A4 - 25.000 610
N3-FC-A5 - 36.367 762
N3-AC-A6 - 50.378 762
N1-HC-A1 +6.700 660
N1-AC-A2 +0.350 406
N1-AC-A3 -10.750 610
N1
N1-FC-A4 -27.500 406
N1-FC-A5 -42.000 406
N1-AC- A6 -62.000 406
WI2-HC-A1 +6.700 610
WI2-AC-A2 +3.151 610
WI2
WI2-AC-A3 -7.000 508
WI2-AC-A4 -22.000 610
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 9 of 11

Elevation OD of brace
Jacket Clamp No/type
(m) clamp
WI2-FC-A5 -40.000 610
WI2-AC-A6 -53.000 660
WI5-HC-A1 +6.700 610
WI5-AC-A2 +4.128 610
WI5-AC-A3 -7.000 508
WI5
WI5-AC-A4 -22.000 610
WI5-FC-A5 -37.000 610
WI5-AC-A6 -54.000 610

TABLE NO.2 I-TUBE CLAMPS

Elevation OD of brace
Jacket Clamp No/type
(m) end clamp
N14(to N18)-HC-A1 + 7.600 610
N14(to N18)-AC-A1 - 9.500 508
N14
N14(to N18)-FC-A1 - 21.960 762
N14(to N18)-AC-A1 - 40.751 864
N18-HC-A1 + 7.600 610
N18-AC-A1 - 9.500 610
N18
N18-FC-A1 - 21.943 762
N18-AC-A1 - 39.854 864
N3-HC-A1 +6.700 660
N3-FC-A2 -8.000 508
N3
N3-AC-A3 -25.000 610
N3-AC-A4 -48.957 762
N1-HC-A1 +6.700 660
N1-FC-A2 -6.000 508
N1 N1-FC-A3 -20.000 508
N1-AC-A4 -42.000 406
N1-AC-A5 -52.000 660
WI2-HC-A1 +6.700 610
WI2-FC-A2 -7.000 508
WI2
WI2-FC-A3 -22.000 610
WI2-AC-A4 -40.000 610
WI5-HC-A1 +6.700 610
WI5-FC-A2 -7.000 508
WI5 WI5-FC-A3 -22.000 610
WI5-FC-A4 -37.000 610
WI5-FC-A5 -54.000 610
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 10 of 11

4.2 MARKING CLAMPS POSITIONS

4.2.1 Hanger clamp and bottom clamp locations shall be defined from drawings and marked by barge
crew and diver respectively.
4.2.2 Hanger clamp may be tack welded to the jacket brace.
4.2.3 A taut wire will be run between these two points by attaching one end to the bottom brace and
pulling the other end by manual winch located over the top brace.
4.2.4 As a check, diver shall measure the distances between intersection points of the taut wire with
the jacket braces and the jacket leg. These measurements should match the dimensions
coming out of the drawings.
4.2.5 If it is matching, another cross check may be done by measuring the distances from taut wire
to another reference point like, for instance, an existing riser.
4.2.6 Once it is confirmed, diver shall mark the points where the taut wire and predefined jacket
braces meet.

4.3 REMOVAL OF ANODES & MARINE GROWTH

During the mark-up of I-Tube clamps’ locations, all obstructions (anodes as well as all other objects
which may hinder the installation of I-Tube clamps) will be recorded and reported to the field engineer.
Anodes removed to facilitate the installation of the riser will be re-instated as they are (if not 100%
depleted).
Removal of marine growth at relevant jacket braces using conventional methods (i.e. scrapers and/ or
water jetting equipment as required) shall be carried-out prior to deployment of the clamps.

4.4 INSTALLATION OF CLAMPS

The clamp batter should be adjusted on deck before it is lowered underwater. This can be done by
using 2 nos come-a-longs being attached to two lifting points connected to the crane wire. These come-
a-longs may be used by the diver underwater for further adjustment. Glow-in-the-dark sticks will be
used to overcome poor visibility.
Flogging/Impact wrench(s) shall be used to bolt up the two brace clamp gates to each other (only if
required, torque wrenches will be used as well).
Riser/I-Tube clamps shall be installed at a batter as per project drawings (Appendix A). To ensure
correct batter during clamp installations, diver will use a batter rectifier.
The Batter Rectifier (fabricated offshore) consists of a triangular steel plate cut to slope requirements
with a spirit level attached on top. After installation of each clamp, a batter check will be performed
whereby the diver places the batter rectifier at 12 O’clock of each clamp’s strut.
Riser/I-Tube clamp shall be adjusted accordingly until the sprit level air bubble is in center, thus
confirming that the I-Tube clamp batter is correct.
For those platforms with a skirt pile on same face where the new riser to be installed; the last bottom
adjustable clamp set (which has been installed on skirt pile brace) will be adjusted so that the riser/I-
tube clamp will be set as close as possible to jacket structure which means an enough gap has been
created with the riser to be installed, as this clamp will be adjusted and closed after riser installation
either by same barge or other vessel.
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 Page 11 of 11

4.5 ALIGNMENT CHECK OF RISER/I-TUBE CLAMPS

Divers will perform an alignment check on the installed riser clamps by running a taut wire through riser
clamps above skirt pile (if any), as the bottom end will be fixed at the center of the bottom clamp, which
should be properly/accurately adjusted prior to and during installation.
On the hanger clamp; a temporary wire guide will be fixed through which the wire will be lowered down
to be connected to the temporary hooking frame fixed on the last bottom inline clamp.
Additional temporary wire guide may be needed to be installed on one of the subsea fixed clamps to
ensure direct leading of taut wire.
Taut wire through wire guide(s) will be kept rigid and tightened, and diver will ensure that there is no
fouling of the taut wire during inspection at each clamp level.
The alignment check is a visual one whereby the diver confirms that the taut wire is in center of each
riser clamp. Necessary adjustments will be made to any riser clamp that does not follow the riser center
line (taut wire).

4.6 INSTALLATION OF HANG-Off CLAMP

Upon completion of Marking-up and alignment operations, hanger clamp shall be welded to the jacket
brace
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VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 APPENDIX A

APPENDIX A
DRAWINGS

RISER CLAMPS DRAWINGS

SN DRAWING NO Drawing title Rev

1. C1004-PPL-SK-060 Taut-wire guide for riser clamp installations. 0
2. COMGD1003-54-1-3008 Typical Anode Relocation Clamp Details 0
3. COMGD1003-54-1-3101 NV Platform – Location of 6" GL Riser and riser clamps 0 (Issue 1)
4. COMGD1003-54-1-3103 WI-2 Platform – Location of 12" WF Riser and riser clamps 0
5. COMGD1003-54-1-3104 N3 Platform – Location of 12" WF Riser and riser clamps 0
6. COMGD1003-54-1-3105 WI-5 Platform – Location of 12" WF Riser and riser clamps 0
7. COMGD1003-54-1-3106 N1 Platform – Location of 12" WF Riser and riser clamps 0
8. COMGD1003-54-1-1501 General Notes For Riser Clamps 1
9. COMGD1003-54-1-3001 Riser Clamp Details - Hanger Clamp 1
Riser Clamp Details - Fixed Clamp -For Existing Platforms (2
10. COMGD1003-54-1-3002
Sheets)
1
Riser Clamp Details - Adjustable Clamp-For Existing Platforms (2
11. COMGD1003-54-1-3003
Sheets)
1

I-TUBE CLAMPS DRAWINGS

SN DRAWING NO Drawing title Rev

1. COMGD1003-54-1-3110 N14 Platform – Location of 660 mm OD I-Tube & I-Tube clamps. 1
2. COMGD1003-54-1-3111 N18 Platform – Location of 660 mm OD I-Tube & I-Tube clamps. 1
3. COMGD1003-54-1-3115 N3 Platform – Location of 610 mm OD I-Tube & I-Tube clamps. 0
4. COMGD1003-54-1-3116 WI-2 Platform – Location of 610 mm OD I-Tube & I-Tube clamps. 0 (Issue 1)
5. COMGD1003-54-1-3117 N1 Platform – Location of 610 mm OD I-Tube & I-Tube clamps. 0
6. COMGD1003-54-1-3118 WI-5 Platform – Location of 610 mm OD I-Tube & I-Tube clamps. 0
7. COMGD1003-54-1-1502 General Notes For I-Tube Clamps 1
8. COMGD1003-54-1-3004 I-Tube Clamp Details - Hanger Clamp 1
9. COMGD1003-54-1-3005 I-Tube Clamp Details - Fixed Clamp – For Existing platforms 1
I-Tube Clamp Details - Adjustable Clamp – For Existing
10. COMGD1003-54-1-3006
platforms
1
 DETAIL-1
DETAIL-1

-+

-+ -+ TAUT
WIRE STD. PIPE

TAUT-WIRE GUIDES AT TOP ,IHANGER CLAMP DETAIL-1

TAUT-WIRE GUIDES AT SUBSEA CLAMPS
(TYP)

II SCHEMATICI
NOTES:
1. ALL DIMENSIONS ARE IN MM. UNLESS OTHERWISE SPECIFIED.
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B46 SEruES, N15 & N16 PIPELINES
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 CONSORTIUM OF
VALENTINE MARITIME LIMITED & VALENTINE
MARITIME MAURITIUS LIMITED
RISER AND I-TUBE CLAMP INSTALLATION
PROCEDURE

VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 APPENDIX B

APPENDIX B
GUIDELINES FOR CLAMP INSTALLATION AT SOME SELECTED PLATFORMS
 CONSORTIUM OF
VALENTINE MARITIME LIMITED & VALENTINE
MARITIME MAURITIUS LIMITED
RISER AND I-TUBE CLAMP INSTALLATION
PROCEDURE

VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 APPENDIX B

B.0 INTRODUCTION
This appendix presents step-by-step procedure for clamp installation at selected platforms to give
barge crew some common guidelines for clamp installation of the whole project
Thorough study of this appendix will give tips for other platforms which is not mentioned herein
below.
B.1 RISER CLAMPS AT NV
1. Hanger clamp at elevation +6.7 m and subsea clamp at elevation -57.193 m shall be used for
marking the location by which taut wire will be passing.
2. At +6.7 m brace, a horizontal distance of 1228 mm will be measured from the inner side of the
jacket leg B2 along the brace to mark the location of the (center of the) hanger clamp; this
distance consists of:
• 1000 mm (distance from WP)
• plus the horizontal projection of the jacket leg from the WP to top brace, which can be
obtained by dividing the vertical projection over 8 (jacket batter)
3. The brace at -57.193 will be marked by the same fashion, so the distance will be:

8.525 𝑚𝑚 + 57.193 𝑚𝑚
1.0 𝑚𝑚 + = 9.215 𝑚𝑚
8
4. Taut wire will be erected from top brace to seabed passing through the two mark places as
mentioned above.

FIGURE 1

1000 mm 228 mm

5. As a check, diver shall measure the distances between intersection points of the taut wire with
the jacket braces and the jacket leg. These measurements should match the dimensions
calculated as above in step 2 and 3; if they are matching then diver can proceed with marking.
6. Diver to mark the locations where the taut wire and predefined jacket braces are intersecting.
7. For the clamp at elevation +1.6, riggers will be involved in marking. A distance will be measured
from the upper end of the diagonal brace at elevation +6.7 to tentatively mark the location of the
clamp; this distance is calculated to be 5.974 m (FIGURE 2); to get this distance, engineer will
 CONSORTIUM OF
VALENTINE MARITIME LIMITED & VALENTINE
MARITIME MAURITIUS LIMITED
RISER AND I-TUBE CLAMP INSTALLATION
PROCEDURE

VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 APPENDIX B

go through a series of trigonometric equations, or instead, construct a sketch which is similar to

FIGURE 2 on a CAD software with the true dimensions.
8. After installing the clamp and performing the alignment check, it may need to be relocated as
this marked location is likely to involve many inaccuracies.
9. For clamp at elevation -20.0 m, the mark will be at 1.0 m to the right hand side of the taut wire.
10. After installing all clamps, the distances between the clamps and the adjacent riser, 8” WI to
N12, will be measured to verify that they are at equal distance of the riser.
11. Anode clamps will be used to reinstall the anodes in a proximate location of the original
location. Totally depleted anodes are not required to be reinstalled.

FIGURE 2

B.2 RISER CLAMPS AT WI-2

1. Hanger clamp at elevation +6.7 m and subsea clamp at elevation -40.0 m shall be used for
marking the location by which taut wire will be passing.
2. At +6.7 m brace, a horizontal distance of 2928 mm will be measured from the inner side of the
jacket leg A2 along the brace to mark the location of the hanger clamp; this distance (as in the
NV platform case) consists of :
• 2700 mm (distance for WP)
 CONSORTIUM OF
VALENTINE MARITIME LIMITED & VALENTINE
MARITIME MAURITIUS LIMITED
RISER AND I-TUBE CLAMP INSTALLATION
PROCEDURE

VML-VMML DOC. NO.: C1004-PR-U-003 REV 0 APPENDIX B

• plus the horizontal projection of the jacket leg from the WP to top brace, which can be
obtained by dividing the vertical projection over 8 (jacket batter)

3. The brace at -40.0 will be marked by the same fashion, so the distance will be:

8.525 𝑚𝑚 + 40.0 𝑚𝑚
2.7 𝑚𝑚 + = 8.766 𝑚𝑚
8
4. Taut wire will be erected from top brace to seabed passing through the two mark places as
mentioned above.
5. As a check, diver shall measure the distances between intersection points of the taut wire with
the jacket braces and the jacket leg. These measurements should match the dimensions
calculated as above in step 2 and 3; if they are matching then diver can proceed with marking.
6. Diver to mark the locations where the taut wire and predefined jacket braces are intersecting.
7. For the clamp at elevation -53.0 m, diver will mark the clamp location at the diagonal brace
where the water depth is 53.0 m; and this will be tentative location as this marking is likely to
involve many inaccuracies.

B.3 RISER CLAMPS AT N3

1. Attention to be paid to the fact that the value “K” is not the same for all clamps which means
that clamps have to be checked prior to installation as to define which clamp (especially fixed
clamps) for which elevation.
2. Marking of the taut wire path could be done by using the hanger clamp location and the clamp
location at elevation -25.0 m.
3. Taut wire will be erected from top brace to seabed passing through the two mark places as
mentioned above.
B.4 RISER/I-TUBE CLAMPS AT OTHER PLATFORM
Riser/I-tube clamps installation tips are believed to be similar to that provided above.