Liwan Deepwater Project

  • January 19, 2017
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COMPANY: EMAS-AMC (SUBCONTRACTOR)

PROJECT TITLE: Liwan Deepwater Project

CLIENT: Husky Oil China

CONTRACTOR: SAIPEM

LOCATION: China

YEAR: 2014

VESSEL: Pipe Lay Barge (DLB) Lewek Centurion

Lewek Centurion is a self-propelled DP2 S-lay pipeline installation vessel, The vessel measures 146.5m long by 30m wide (35m wide included the external thrusters), with mean operating draft of 7.8 m. The pipe lay ramp is located on the center of the barge and runs the entire length of the barge.

The vessel is equipped with one pipe transfer crane and one shipboard crane. The pipe transfer crane has a maximum capacity of 36MT at 30m radius, and the shipboard crane has a maximum capacity of 20MT at 25m knuckle boom. The main crane is a 300 MT Kenz crane at 15-16m radius.

LCE is also equipped with 300mT A-Frame and retractable Hang off Platform at port side with 300mT capacity at maximum retraction.

All of the vessel accommodation is located above the main deck, and is fully air conditioned with a mess hall and recreational facilities. A helideck is located over the bow superstructure and is capable of accommodating an S61 helicopter.

MULTI SUPPORT VESSEL (MSV): Volantis

During jumper installation LCE will be assisted by two (2) units of ROV onboard a MSV provided by CONTRACTOR

SCOPE OF WORK:

This document provides all the relevant project data and procedure for installation of 12’’ in-field flowline and associated activities from KP 8.044 to KP23.002 (East Manifold). It is approximately 15 km and the water depth ranges from 1115 m to 1410 m. The installation sequence is as below:

1) Recover existing 12’’ Pipeline @ KP 8.044 (Well LH34 Area) in J-Lay Mode

2) Remove existing 12’’ Pipeline laydown head

3) Replace new 12’’ Pipeline laydown head (for S-Lay Recovery)

4) Laydown existing 12’’ Pipeline @ KP 8.044 in J-Lay Mode

5) Recover existing 12’’ Pipeline @ KP 8.044 in S-Lay Mode

6) Remove laydown head and continue 12’’ pipelay

7) Laydown the pipeline with collar and laydown head (for PLET 7 Installation) @ KP 23.002 (East Manifold)

In addition, this document also covers the preparation works for the 12’’ CRA PLET 8 at Well LH34 area including:

1) Recover existing 12’’ Pipeline @ KP 0.00 (Well LH 34 Area) in J-Lay Mode

2) Remove existing 12’’ Pipeline Start-up head

3) Replace new 12’’ Pipeline Start-Up head (for S-Lay Recovery)

4) Laydown existing 12’’ Pipeline @ KP 0.00 in J-Lay Mode

5) Recover existing 12’’ Pipeline @ KP 0.00 in S-Lay Mode

6) Remove start-up head and install CRA collar and laydown head for PLET 8 Installation

7) Laydown the pipeline in S-Lay mode

The procedure also includes the following details:

  • Pre-installation activities and preparation.
  • Handling, preparation, welding and laying of pipeline.
  • Details of Marine spread, equipment, and installation aids.
  • Survey requirement during pipeline installation.
  • Abandonment and recovery (A&R) procedure.
  • Contingency procedures.

Pipe Lay Installation Vessel “Lewek Centurion” will be utilized to perform this installation. An ROV survey support vessel provided by CONTRACTOR will be employed at certain time during pipelay to provide the ROV survey and touch down monitoring for Lewek Centurion.

MY INVOLVEMENT:

I developed the procedure and executed the pipelay offshore.

INTRODUCTION

EMAS-AMC was subcontracted by Saipem to perform the installation of pipelines as part of Liwan 3-1 Area Facilities Development Project. The works involved installation of two (2) pipelines including its pipeline end terminals (PLET’s), four (4) in total, and lifting support of two (2) spools which will be installed offshore in South China Sea, approx. 300 km south from Hong Kong in a water depth range from 1100 to approx. 1400 meter. EMAS-AMC mobilized its pipelay vessel, the Lewek Centurion, end of March 2014 in Singapore for an arrival date of 28th April 2014 at latest in Shekou, China, for inward clearances and pipe load out. The installation activities were estimated to last approximately two (2) months

Pipeline Data

12’’ Infield LH-34 Flowline Data

Route Length KP 8.044 – KP 23.002
Pipeline Termination at KP 0 PLET P8, LH-PLT-02 (E 351846.97; N 2217132.30 – centre of PLET )(1), WD – 1,115m
Pipeline Termination at KP 23.002 PLET P7, EM-PLT-05 (E 337755.43; N 2205895.97 centre of PLET) (1), WD – 1,335m
Soil Characteristics Very Soft Silt/Clay
Outside Diameter 12.75” (323.9mm)
Wall Thickness 19.1mm
Nominal Line Pipe Length 12.67m
Manufacturing Process SMLS
Material Grade DNV450
SMYS 450 MPa
Young Modulus 207,000 MPa
Poisson Ratio 0.30
Steel Density 7850 kg/m3
Weight Weight in Air 146.4 kg/m (1855 kg/Joint)Submerged Weight (Empty) 58.8 kg/m (741.2 kg/Joint)Submerged Weight (Flood) 124.5 kg/m (1577.4 kg/Joint)
Ext. Corrosion Coating 3 Layer Polyethylene (3LPE), 3mm thk, 910kg/m3
Ext. Corrosion Coating Cutback 170mm (Tolerance -0,+20mm)
Field Joint Coating Heat Shrink Sleeve Polyethylene (HSS PE), 2.5mm thk, 910kg/m3
Anode Bracelet Anode, 24.2 kg each, Every 12 Joints SpacingNote: One additional anode to be added on the last & first joint and before & after the crossing.
Crossing 2ea Cable Crossing (Undetected Cable, No Sleeper Required)Crossing C24 :E 339628.720; N 2207699.390 (KP 20.285)Crossing C21 : E 338516.130; N 2207115.350 (KP 21.560)
Curve 3ea Pipelaying around CurveIP1 – 3,000m Radius/ IP2 – 1,500m Radius/ IP3 – 2,000m Radius
Allowable Freespan 45.3m (Empty) / 42.5m (Operating)

Pipeline Installation Parameter

12” In-Field LH34-2 Flowline Installation Parameters

PL Recovery at KP 8.044, Well LH34 Area
PL Laydown at KP23.002, East Manifold Side
Recovery Joint Coordinate (KP8.044) E 351877.53, N 2209336.35 (Existing)(1)
Target Hang-off Collar Coordinate at Laydown (East Manifold side) @ PLET 7 E 337759.47,  N 2205903.23
Recovery Joint Coordinate (LH34-2) @ PLET 8 E351850.97, N 2217121.05 (Existing)(1)
Target Hang-off Collar Coordinate at Laydown(LH34-2) @ PLET 8 E 351848.77, N 2217123.44
Start-up Method Existing Pipeline recovery & continue normal lay
Water Depth (MSL) 1115m to 1410m
Recovery Head 12” Pulling Head
Laydown Head 12” Pulling Head
Stinger 2 Sections
Stinger Angle 52 Degrees
Stinger Tip Depth (from MSL) 67.8 Meter
Recovery Tension J-Lay Mode (Static) 91mT
Normal Lay Tension S-Lay Mode (Static/Dynamic) 100mT / 172mT
Max Laydown Tension S-Lay Mode (Static) 103mT
Layback Distance Range from Barge Stern (Normal Lay) 674m (1310 Min. WD) to 725m (1410 Max. WD)

Installation Tolerance

The following installation tolerances will be maintained during the pipelay activity:

Description Laying Tolerance
Laying Corridor ±15m Either Side of Intended Pipeline Route
PLET P7, EM-PLT-04

East Manifold side

 Longitudinal ±5m,

Lateral ±3m

Heading ±2.5 Degrees
PLET P8, LH-PL-02

Well LH34 side

 Longitudinal ±5m,

Lateral ±3m

Heading ±2.5 Degrees

FIELD LOCATION

 

LOADOUT & TRANSPORTATION

SUBCONTRACTOR project specific materials such as installation aids, equipment, etc will be mobilized and loaded on Pipe Lay Vessel “Lewek Centurion” from the mobilization point in Singapore.

For the project permanent materials which are supplied by CONTRACTOR such as Coated Linepipes, Anode, Buckle Arrestors, Collars, Linepipe coating repair materials, HSS, etc, they will be loaded on 300 class cargo barge as arranged by CONTRACTOR and transported to Pipe Lay Vessel “Lewek Centurion” at Shekou anchorage after approval given by local authority and/or CONTRACTOR. Transportation, seafastening, logistic, including all other arrangements on these cargos will be under sole responsibility of CONTRACTOR.

Upon the cargo barge arrival at LCE, the SUBCONTRACTOR will alongside transportation vessel to LCE starboard side and transfers the cargo on to LCE’s deck storage area as appropriate. Joint inspection survey between CONTRACTOR and SUBCONTRACTOR will be conducted to check if there is any damage and/or loss of cargos during the passage of transportation vessel to LCE location.

During the loadout operation, the towing tug can serve as an FRC to assist in case of man overboard incident.

Refer to Proposed Stowage Plan 300’ Barge for Pipeline Dwg No: F12416-SAI-010-OPS-DWG-10551-01 to 03 in Appendix 1.


MATERIALS, EQUIPMENT & INSTALLATION AIDS

COMPANY/CONTRACTOR Supplied Items

Items below are to be supplied by COMPANY / CONTRACTOR for the 12’’ pipeline installation scope:

No Items Req. Qty (Pcs) Spare Qty (Pcs) Total Qty

(Pcs)
1 323.9 OD X 19.1MM WT  X 12.67M C/W 3LPE Coating 1183 46 1229
2 323.9 OD X 19.1MM WT  X 12.67M C/W 3LPE Coating Buckle Arrestor (23MM WT X 0.832M LGTH) 27 2 29
3 Forged Hang-off Collar with 323.9mm OD x 16.8mm CS + 2.5mm CRA WT Pup-Piece Welded Both End 1 – 1
4 Forged Hang-off Collar with 323.9 OD x 19.1mm WT Pup-Piece Welded Both End 1 – 1
5 323.9mm OD x 14.3mm CS + 2.5mm CRA WT Pup Pieces of 1m length – 5 5
3 24.2 kg Bracelet Anodes with cables and lugs 103 34 137
4 12” Heat Shrink Sleeve + Primer (GTS PE) 1184 63 1247
5 Linepipe Coating Repair Kit 100 0 100
6 Acothane For each Anode 103 34 137
7 CRA Welding Consumables – – 1 Lot
8 X-Ray Equipment and personnel – – 1 Lot


SUBCONTRACTOR Pipeline Installation Equipment

The following is the brief description of the vital pipelay equipment mounted onboard Lewek Centurion:

Equipment Particulars Quantity
Stinger Type : Truss stinger 2 x Section
No. rollers : 13ea (R3-R9 on Sect.1, R10-R15 on Sect.2)
Length : 89.6 m
Weight(air) : 949 MT
Tensioner Type : Horizontal Track Grip 3 x Unit
Make : SAS
Length : 7 m
Capacity: : 135 MT each
A&R Winch Type : Electric Driven Winch 1 x Unit
Make : SAS
Capacity : 450 MT
Cable : 109mm dia

In additions, SUBCONTRACTOR will mobilize the following installation aids, tools & equipment, riggings, and consumables from mobilization point of Lewek Centurion in Singapore for 12’’ pipeline installation work scope.

No Items Req. Qty Spare Qty Total Qty
1 Pipeline Start-up, Laydown, and A&R Head 3 Nos – 3 Nos
2 Internal Line-up Clamp 1 Pc 1 Pc 2 Pcs
3 Holiday Detector 1 Pc 1 Pc 2 Pcs
5 Line Pipe Handling Rigging c/w spreader bar and pipe handling hooks 1 Lot 1 Lot 2 Lot
6 Linepipe Marking 1 Lot 1 Lot 2 Lot
7 Welding Equipment and Consumables 1 Lot – 1 Lot
8 Survey Spreads 1 Lot – 1 Lot
9 Field Joint Coating Spreads 1 Lot – 1 Lot
10 AUT Spread 1 Lot – 1 Lot
11 PRT and DWC Spreads (Standby Onshore) 1 Lot – 1 Lot
12 Pipeline Start-up, Laydown, and A&R Riggings 1 Lot 1 Lot 2 Lot
13 ROV Hook (Various Size) 1 Lot – 1 Lot
14 Subsea Buoy – 120KG Net Buoyancy 1 Pc 1 Pc 2 Pcs

EQUIPMENT SET-UP for Pipelay

Vessel Trim & Draft and Stinger Angle

During the pipelay operation, the vessel and stinger setting will be set as following:

Description Barge Parameters
Vessel Draft 9.35 m
Vessel Trim 0 Degrees
Stinger Angle 52 Degrees
Stinger Radius 80 m

 

Vessel Roller & Tensioner Profile Set-Up

Prior to pipelay operation at site, vessel rollers & tensioners will be set as listed in below table.

Vessel Rollers A B C D E F G H I J K R1 R2
Distance from Hitch (m) 112 109 97 88 81 72 63 57 48 39 32 23 11
Bottom of Pipe Elev (m) 9.68 9.68 9.68 9.68 9.68 9.68 9.68 9.68 9.68 9.68 9.68 9.39 7.69

Notes:

  1. A refers to the first vessel roller nearest to Station-0 at the bow.
  2. Vessel trim angle is set to 0 degrees w.r.t center of laybarge
  3. The barge B.O.P elevations are measured from the main deck level to the bottom of pipe (with no barge ramp considered).
  4. Refer Dwg No: 16009-AMC-OPS-DWG-015-01 “Stinger Operational Settings Pipeline Radius 80m” in Appendix 2

Stinger Profile Set Up

The Stinger will be set up to suitable/sufficient for pipeline installation as listed in below table.

Stinger Rollers R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15
Distance from Hitch (m) -3.4 -11 -17 -23 -29 -34 -39 -44 -47 -50 -52 -54 -55
Bottom of Pipe Elev (m) 3.7 0.7 -2.9 -7.2 -12 -17 -23 -31 -37 -44 -52 -59 -66

Notes:

  1. R3 refers to the first stinger roller nearest to the hitch of the stinger.
  2. The stinger B.O.P elevations are measured from the location of the stinger hitch at the stern of the barge.
  3. The bottom of the pipe elevations presented in the table are based on actual elevations of the roller boxes available in the stinger.
  4. Refer Dwg No: 16009-AMC-OPS-DWG-015-01 “Stinger Operational Settings Pipeline Radius 80m” in Appendix 2

Survey & Positioning

General

This section outlines the survey procedures required before, during, and after the pipelay. For further technical specifications on the survey and positioning systems refer to [Ref 49].

Vessel Surface and Underwater Positioning

Primary survey system used for LCE surface positioning and other vessel tracking is DGPS. A computerized vessel navigation system will be utilized to graphically display the current location and heading of LCE. The data of position and heading of ROV and survey support vessel will be also telemetry transferred and displayed.

Underwater positioning will be carried out by CONTRACTOR’s ROV survey support vessel, Acoustic positioning will be carried out with the use of ROV with Inertial Navigation System (INS) mounted and interfaced with DVL, mini-SV & mini-IPS. LBL array will used for the laydown of the pipeline to achieve the installation tolerance as defined in Section 8.5.

Pre-Installation Survey

Pre-installation debris survey has been carried out by CONTRACTOR Survey ROV vessel prior to LCE arrive at site for the recovery of the 12’’ pipeline installation.

Installation Survey

During the course of the pipelay, the main survey activities will consist of vessel track control, and pipeline touchdown tracking.

A remote monitor is installed for DP operator on the bridge showing the proposed pipeline route with the image of lay vessel overlaid. The vessel position will be updated in real time allowing the operator to move the vessel on line during pipe pulls. When laying in a curve, pipeline actual layback distance will be monitored.

As mentioned in Section 8.2, CONTRACTOR will provide dedicated ROV Survey Support Vessel to support the survey during the pipe laying.

During pipeline startup, and laydown including when there is abandonment and recovery of pipeline, the ROV shall be used to monitor touchdown of the pipeline and record a fix as necessary.

During crossing, pipelay around a curve, and when laying near existing subsea or surface facilities, ROV shall be deployed to provide continuous monitoring of the pipeline touchdown.

During normal laying, pipeline touchdown monitoring shall be performed as required when pipelay occurs in open water

As-Built Survey

As-built surveys shall be completed by CONTRACTOR.

Geodetic Parameters

Pipeline laying will be carried out based on Geodetic Parameters as following:

Description Data
Horizontal Coordinate System WGS84 / UTM Zone 50N
Geodetic Datum Name WGS84
Ellipsoid Minor Axis 6 378 137.000 meter
Ellipsoid Major Axis 6 356 752.314 meter
Ellipsoid Inverse Flattening 298.257 223 563
Project Name UTM Zone 50N
Projection Method Transverse Mercator
Projection Latitude of Origin 0 degrees N
Projection Longitude of Origin 117 degrees E
Projection Scale Factor at Origin 0.9996
Projection False Easting 500 000.0 meter
Projection False Northing 0 meter
Grid Unit meter
Vertical Coordinate System Unit meter

PIPE LAYING

General

This section covers the pipelay procedures, which includes the following:

  • 12’’ Pre-Installation Activities
  • 12’’ Pipeline Recovery Procedure
  • 12’’ Pipeline Normal Lay Procedure
  • 12” Pipeline Laydown Procedure
  • Contingency Procedure

Pre-Installation Activities

Linepipe Storage and Handling

Linepipes will be transported to LCE at Shekou anchorage, China, via CONTRACTOR’s 300ft cargo barges. Linepipe cargo barge is to be preferably alongside at starboard side of LCE (same side with pipe loading hatch) depending on prevailing weather and actual site condition. Lashing will be removed and the pipe will be lifted off from cargo barge and transfer down to “Pipe Hold Area” at 2nd deck of LCE. Special pipe lifting hooks shall be used to handle the loading and unloading of linepipe.

The pipe will be temporary stored at “pipe hold area at 2nd deck” in 4 bays between portable stanchions. They will be subsequently maneuvered into pipe handling system during the operation.

Ref Dwg No. 16009-AMC-OPS-DWG-152-00 “Lewek Centurion 36MT Crane Lift For Pipe Loading”, 16009-AMC-OPS-DWG-153-00 “Lewek Centurion 12’’ & 4’’ Pipe Hold Area” & 16009-AMC-OPS-DWG-415-00 “12INCH Line Pipe Handling Rigging Detail” in Appendix 2.

Stacking analysis for linepipe transportation is to refer to [Ref 33].

Linepipe Preparation

Following outlines the preparation work to be done on linepipe prior commencing production welding.

  1. Linepipe shall be checked for any obvious deformities, i.e. out of roundness, corrosion coating damage, etc. If the damage is found to be unacceptable and not possible to repair; it will be rejected and marked for quarantine.
  2. Pipe end to be inspected for damage.  Note that the supplied linepipe is without bevel end i.e. square cut.
  3. Tallyman to collect and record pipe number, heat number, and total length into pipe tally sheet.
  4. Linepipes will be transferred from “Pipe Hold Area” to bevel conveyor on production deck by “Pipe Elevator”.
  5. The debris will be blown out using compressed air.
  6. Pipe ends will be bevelled with pipe facing machines prior transfer to line-up station via conveyor.
  7. The bare ends of the pipe will also be pre-heated for welding if required.

Pipelay Preparation Checklist

Prior to commencing of pipeline initiation, the following preparation work shall be completed:

No. Check List Description Resp
1 Vessel Trim Check vessel trim as per Section 7.2.3 MASTER/FE
2 Stinger Check vessel and stinger roller height as per Section 7.2.3 BF/FE
Check stinger angle is as per Section 7.2.3 BF/FE
3 Pipe Conveyor Check readiness of debris blower bucket and air source BF/FE
4 QC Check readiness of Pipe Tally Sheet record. QC/FE
Check QC tools e.g. Holiday detector, Jeep Meter, Temp Stick etc are available for the work at each station. QC
5 Firing Line Check readiness of pipe facing machine SRMX/BF/FE
Check readiness of tugger winch for internal line-up clamp BF/FE
Check readiness of preheat torch and propane gas source BF/WF
Check readiness of grinding / buffing machines BF/WF
Check readiness of pipe line-up clamp WF/SRMX
Check readiness of waterproof marine paint for joint numbering BF
Check welding equipment is functioned and consumables are ready. WF/SRMX
Check NDT equipment, consumable and personnel are ready. WF/SHAW
Set tension machine shoes to suit 12.75” (323.9mm with 3mm 3LPE coating) OD BF
Set up Tensioner clamp pressure to suit lay tension. BF
Check readiness of anode and field joint coating materials including repair kits at the station. PIH/BF/FE
Check readiness of anode installation clamp and hydraulic at station. BF/FE
Check readiness of FJC tools at each station e.g. Blasting Frame & Pot, Heat Induction Coil, Generator, Air Compressor, Heating Torch, etc. PIH/BF/FE
6 Survey & ROV Check survey equipment, personnel, and all information required for the pipeline start-up and pipelay. Survey
Ensure latest field layout and existing subsea facilities as provided by CONTRACTOR / COMPANY are demonstrated on the survey screen. Survey
Function test on ROV wire cutter. (On ROV Survey Vessel) ROV SUP/FE
7 Recovery/ Laydown
Heads		 To be noted on the following:

  • Recovery / Laydown heads are identical.
  • There is no valve or port on the Recovery / Laydown heads.
  • There is no plan for pigging operation with this Recovery and Laydown heads.
 BF/FE
8 Riggings Check readiness of laydown and recovery riggings. BF/FE
Check readiness of line pipe handling rigging BF/FE
9 Others Check all the station light and pipe pulling alarm are functioned. BF
Check all inter-communication with all related personnel are established BF

Pipeline Start-up

General

The partially laid 12’’ pipelines will be recovered in J-Lay mode at KP 8.044 and the A&R head will be replaced with a new S-lay head. After the replacement is completed, the 12’’ pipeline will be laid down using the J-Lay mode configuration. The 12’’ will be then recovered in S-lay mode. The pipeline will be laid in S-lay mode until KP 23.002.

12’’ Recovery in J-Lay Mode @ KP 8.044

Step-by-step procedure for the 12” Recovery in J-Lay mode is outlined in the below table:

  • Status:
    -Project brief completed.
    – Toolbox talk has been conducted with all personnel involved in the operation.
    – Perform communication check prior to operation commencing including but not limited to: bridge, shift supervisor, deck foreman / barge foreman, crane operator.
    – A & R wire  &109mm rerouted through the A-Frame Sheave with the open spelter socket re-instate.
    – A&R Frame set to the required angle.
    – Work platform is fully retracted
    – Spider clamp is installed and rigged up on work platform and spider clamp door is fully open and secured.
    – Air tugger is installed A-Frame vicinity
    – Survey Vessel is at standby position on the LCE port side.
    – ROV deployed on Survey Vessel and standing by in water.
    – Completed general deck preparations for welding, cutting, i.e. function check
    – All survey data is displayed on vessel navigation screen.
    – PTW in place.
    – Weather Forecast has been assessed for installation window.
  • Set-up LCE with the A-Frame directly above to the laydown head to the partially laid 12’’ pipeline @ KP 8.044. Ref Dwg No. 16009-AMC-OPS-DWG-352-01 “12’’ Pipeline Recovery in J-Lay Mode @ KP 8.044” in Appendix 2.
  • Lower A&R wire to the sea bed with ROV hook while ROV to monitor winch wire
  • Once ROV hook is at sea bed, position the ROV hook to the laydown rigging by moving the vessel
  • ROV to connect hook to laydown rigging
  • Start to pick up slack on laydown rigging by paying in A&R wire while LCE moves away 495 meter from A&R head
  • Start recovering pipeline in J-Lay mode by moving the vessel and paying in the A&R wire according to the analysis report [Ref 50].
  • ROV to monitor recovery the 12’’ pipeline process at touchdown point
  • Continue to pay in A&R wire until the 12’’ pipeline above the work platform height and all stop.Refer Dwg No. 16009-AMC-OPS-DWG-352-02 “12’’ Pipeline Recovery in J-Lay Mode @ KP 8.044” in Appendix 2.
  • Extend work platform until the 12’’ pipeline slides into the work platform opening
    Note: Air tugger can be used to assist to pull in the 12’’ pipeline into the platform opening or move vessel towards port. Total vessel movement approximately 1650m.
  • Close the spider clamp door and insert lock pin on spider clamp support frame
  • Activate the spider clamp and clamp the 12’’ pipe below the A&R head
  • Slowly transfer the load from A&R wire to the spider clamp
  • When load is fully transfer to spider clamp, hold 12’’ pipe with A&R wire for 5 minutes to monitor if there is any slippage on the spider clamp
  • Disconnect A&R wire from laydown head
  • Retrieve A&R wire until the spelter socket is at the A-Frame sheave

12’’ Head Removal and Laydown in J-Lay Mode @ KP 8.044

Step-by-step procedure for the 12” Head removal and laydown in J-Lay mode is outlined in the below table:

  • Status:
    – Project brief completed.
    – Toolbox talk has been conducted with all personnel involved in the operation.
    – Perform communication check prior to operation commencing including but not limited to: bridge, shift supervisor, deck foreman / barge foreman, crane operator.
    – Completed general deck preparations for welding, cutting, i.e. function check
    – 12’’ pipe is resting on spider clamp
    – All survey data is displayed on vessel navigation screen.
    – PTW in place.
    – Weather Forecast has been assessed for installation window.
  • Install cutting tool to J-Lay laydown head
  • Refer Dwg No. 16009-AMC-OPS-DWG-353-00 “12’’ Pipeline Laydown Head Replacement @ KP 8.044” in Appendix 2.
  • Connect crane to J-Lay laydown head
  • Cut J-Lay laydown head and recover to deck by crane (weight of J-Lay Head = 1 MT)
  •  Crane to pick up new S-Lay laydown head and slew towards A-Frame (weight of S-Lay Head = 1 MT)
  • Line up S-Lay laydown head to the 12’’ pipeline using external line up clamp
  •  Weld S-lay laydown head and NDT weldment
  • Lower A&R wire with ROV hook to work platform
  • Connect ROV hook to S-lay laydown head rigging with buoy
    Ref Dwg No. 16009-AMC-OPS-DWG-406-00 “12’’ Pipelay Laydown Rigging Arrangement (J-Lay Mode) & Recovery (S-Lay Mode) in Appendix 2.
  • Pick up slack on laydown rigging by paying in A&R wire
  • Slowly transfer spider clamp load to A&R wire
  • Once load is transfer, de-activate spider clamp and open spider clamp door
  • Re-tract work platform.
    Ref Dwg No. 16009-AMC-OPS-DWG-354-01 “12’’ Pipeline Laydown in J-Lay Mode @ KP 8.044” in Appendix 2.
  • Start lowering pipeline in J-Lay mode by moving the vessel and paying in the A&R wire according to the analysis report [Ref 50].
  • ROV to monitor the 12’’ pipeline lowering process
  • Once S-Lay laydown head is on sea bed, ROV to take fix at the S-Lay Laydown head location.
    Ref Dwg No. 16009-AMC-OPS-DWG-354-02 “12’’ Pipeline Laydown in J-Lay Mode @ KP 8.044” in Appendix 2.
  • ROV to disconnect ROV Hook

12’’ Recovery in S-Lay Mode @ KP 8.044

Step-by-step procedure for the 12” Recovery in S-Lay mode is outlined in the below table:

  • Status:
    – Project brief completed.
    – Toolbox talk has been conducted with all personnel involved in the operation.
    – Perform communication check prior to operation commencing including but not limited to: bridge, shift supervisor, deck foreman / barge foreman, crane operator.
    – 12’’ pipeline laid down
    – A & R wire  &109mm re-routed through the firing line until stinger end with the open spelter socket re-instate
    – Survey Vessel is at standby position on the stern.
    – ROV deployed on Survey Vessel and standing by in water
    – Completed general firing line preparations for welding, cutting, FJC and etc. i.e. function check
    – All survey data is displayed on vessel navigation screen.
    – PTW in place.
    – Weather Forecast has been assessed for installation window.
  •  Set-up LCE stinger above the laydown head to the partially laid 12’’ pipeline @ KP 8.044. (Stinger settings as per Section 7.2.3.3). Ref Dwg No. 16009-AMC-OPS-DWG-360-01 “12’’ Pipeline Recovery in S-Lay Mode @ KP 8.044” in Appendix 2.
  • Lower A&R wire to the sea bed with ROV hook while ROV to monitor winch wire
  • Once ROV hook is at sea bed, position the ROV hook to the laydown rigging by moving the vessel
  • ROV to connect hook to laydown rigging
  • Start to pick up slack on laydown rigging by paying in A&R wire
  • Start recovering pipeline in S-Lay mode by moving the vessel and paying in the A&R wire according to the analysis report [Ref 50].
  • ROV to monitor recovery the 12’’ pipeline process.
    Ref Dwg No. 16009-AMC-OPS-DWG-360-02 “12’’ Pipeline Recovery in S-Lay Mode @ KP 8.044” in Appendix 2.
  • Continue recovering pipeline using the A&R winch until laydown head pass all tensioners. Transfer tension from A&R winch to Tensioner.
  • Disconnect A&R wire from head.
  • Remove S-Lay Head and the triple pipe joint [Ref 24]
  • Continue normal lay. Ref Dwg No. 16009-AMC-OPS-DWG-361 “12’’ Pipeline Normal Lay” in Appendix 2. For Dynamic Analysis Result for “Straight and Curve Route” to refer the analysis report [Ref 50].

Pipeline Normal Lay Operation

General

Once pipeline is recovered from seabed as per Section 9.3, LCE will continue pipelaying on normal lay mode. Linepipe will be laid in single joint. Prior to feeding the single joint, the linepipe will be prepared as per “Section 9.2.2 Linepipe Preparation”. Along firing line, each station will be assigned for welding, NDT, and field joint coating activities as shown in the below table.

Ref Dwg No. 16009-AMC-OPS-DWG-013 “12’’ Pipeline Firing Line Arrangement” in Appendix 2. Station layout may change on site depending on site condition.

Station No. Activities
1 Welding: Line-up/Root/Hot-Pass
2 Welding: Filling
3 Welding: Filling/ Capping
Tensioner Machine #1
4 NDT/ Repair
5 Not In Use
Tensioner Machine #2
6 FJC: Blasting
7 Not In Use
Tensioner Machine #3
8 FJC: Induction Heating + Epoxy Primer + Curing Heat Shrink Sleeve Application
9 FJC: Quenching
9A Anode Installation: Welding & Pin Brazing

Pipeline Welding

Linepipe is transferred laterally into the line-up station and aligned with the last joint of the pipeline in station one (beadstall).

Fitting up of pipeline will be accomplished using an internal line up clamp. Hydraulic rams will be used to move the new joint of pipe on the line up rack in three dimensional to align pipe facing.  Upon achieving sound fit up, the internal line up clamp will be engaged and welding will be commenced.

Root and hot passes will be run at 1st station. Upon completion of hot pass weld, the pipe joint will be pulled to 2nd station and subsequent filler passes will be run. The pipe will be pulled further to 3rd station for further filler pass and capping.

Automatic welding will be conducted by qualified welders for the 12’’ pipeline.  WPS shall be in accordance with Pipeline Welding Procedure Specification (WPS) [Ref 42].

Non Destructive Examination

Upon completion of the cap weld, the pipeline will be moved to 4th station where the weld will be AUT according to the procedure [Ref 46].

Designated weld repair locations is 4th station.  All repair welding will be done at 4th station, immediately after the sentence of the defect.  And then the re-AUT [Ref 46] of the repair joint will be performed also at 4th station. The pipe pull will wait until the repair complete. If required, joint cut out may be performed at 1st station. Full joint cut out will be subject to CSR and OCM approval.

The welding inspection after repair will be conducted in the same manner as for the original weld.

The following figures show results of allowable weld repair length [Ref 50].

Allowable Weld Repair Length
Full thickness Repair Partial Thickness Repair
204mm 305mm

Buckle Arrestor

Along Production Line route, buckle arrestor will be installed during pipelay operation.

The buckle arrestor is already pre-welded at the center of the pipe joint onshore by CONTRACTOR. The buckle arrestor will be installed at a spacing of 1 buckle arrestor at every 45 joints.

Field Joint Coating

The field joint coating for the pipeline is Heat Shrink Sleeve (Canusa GTS PE) plus Primer [Ref 48].

Once the weld has been found accepted, the pipe joint will be blast cleaned including overlap preparation at 6th Station in between tensioner #1 and #2.  At 8th station, the induction heating using induction heating coil, liquid epoxy primer application, and post curing will be performed, which is subsequently followed by application of Heat Shrink Sleeve and quenching/cooling.

Anode

Bracelet Anode Al-Zn-In, 24.2 kg to be installed at 9A station [Ref 45].

Anode installation clamp will be utilized to pull each half of anode together. Hydraulic jack will be also used to push-up the bottom half anode against the pipe prior to commencing the welding. Pin brazing equipment and material will be provided for connection of the electrical bonding cable to pipe at 4 locations. Linepipe coating repair due to anode installation will be performed at the same station. Anode will be tested with 1 kg hammer and ohm meter is used to check the current connecting of approximate 0.1 ohm meter.

Lay Tension and Environmental Limits

Tensioners and stinger are the main equipment that is used to control pipeline profile during pipelaying operation. Laying tension, and stinger angle & configuration will be closely controlled and monitored to ensure that pipeline stresses are within limit.

For further details pipelay tension in various environmental limits to refer to the analysis result [Ref 50].

Pipelay Monitoring Parameters

The following works shall be performed for monitoring pipelay parameter during normal lay mode:

Activities By Frequency Function Report
ROV Check ROV 4 Times a Day Check pipeline profile from stinger to touchdown point ROV Log Sheet
Lay Tension Bridge 4 Times a Day Record lay tension Log Sheet
Pipe Tally QA/QC Continuous Traceability of laid pipe joint detail Pipe Tally Sheet
DPR Project Admin Daily Capture all vessel and construction activities, POB and marine spread movement DPR

Note:

(1) Additional ROV monitoring might be required to ensure the safe pipelay operation at discretion of OCM.

(2) ROV monitoring is required for critical operation i.e. start-up, laydown, curve section and etc.

Pipeline Laydown

12 inch in-field flowline will be laydown at East Manifold side. The target box will be determined such that PLET installation can be positioned within the required tolerance as stated in Section 8.5. Below is step-by-step guideline for pipeline laydown:

  • Once LCE beadstall approaching target laydown point, the amount of pipe joint to be laid will be determined by FE.
    Notes: The last joint before pulling head welding joint shall be pup-piece joint welded to hang-off collar section.Ref Dwg No. 16009-AMC-OPS-DWG-362-01 “12’’ Pipeline Laydown @ KP 23.002” in Appendix 2.Ref Dwg No. 16009-AMC-OPS-DWG-110-00 “12’’ Hang – Off Collar at PLET P7 with pup piece” in Appendix 2
  • Transfer the pup-piece joint into tunnel to weld to the second last joint at beadstall.
  • Transfer the hang-off collar joint section with pup piece and weld to pipeline at beadstall. (Note: By automatic welding) [Ref 42]
  • Transfer the laydown pulling head into tunnel to weld to the hang-off collar pre-section at beadstall.
  • Complete NDT & field joint coating for all remaining joints.[Ref 46][Ref 48]
  • Install collar protector at the collar section
    Ref Dwg No. 16009-AMC-OPS-DWG-108-00 “12’’ Collar Protector” in Appendix 2.
  • Install laydown riggings and A&R cable. Note: Sacrificial and recovery riggings shall be paint white or other high visibility color for ROV to see underwater.Ref Dwg No. 16009-AMC-OPS-DWG-407-00 “12’’ Pipelay Laydown Rigging Arrangement (S-Lay Mode) in Appendix 2.
  • Continue move vessel forward till the pulling head is close to bow tensioner.  Then take up load on A&R while open bow and stern tensioners.
  • Slowly payout with tension of A&R winch till laydown head is under water.  ROV to be deployed to monitor laydown head passing stinger and elevation depth. Refer the analysis report [Ref 50] for Abandonment Analysis.
  •  ROV to free recovery rigging off laydown head prior to touching down on seabed.
  • Keep payout whilst maintain tension till laydown head touchdown on seabed.  ROV to temporarily take fix on the pulling head and hang-off collar.
  • If there is not much deviation in position with respect to the target box, move LCE astern. ROV to take fix again to re-confirm compliance of the installation tolerance.
  •  LCE to move backwards till stinger tip is above laydown pulling head is. ROV to perform sacrificial wire cutting. Ref Dwg No. 16009-AMC-OPS-DWG-362-02 “12’’ Pipeline Laydown @ KP 23.002” in Appendix 2.
  • After cutting-off sacrificial wire, recover A&R winch wire to surface.

Emergency A&R Procedure

During pipelaying operation, if the environmental conditions are such that the LCE cannot hold the position, and/or excessive movements are caused in the pipe/stinger, it may become necessary to discontinue the pipelaying operation and abandon the pipeline.

Environmental condition for pipelaying abandonment is depend on vessel motions (pitch, heave, and roll), taken into account other weather parameter such as wind speed, sea state condition etc.

Decision to abandon the pipeline will be made by OCM after consultation with CSR and onshore management wherever possible.

For abandonment and recovery tension tables to refer to analysis report [Ref 50].

Following guideline is step-by-step procedure for emergency laydown:

  • Remove all internal equipment from pipeline interior, if any.
  • Weld emergency laydown head onto the last welded joint and finish the weld at welding 1st Station.[Ref 42]
  • Finish all remaining weld. Record the last joint number where NDT is performed.[Ref 46]
  • Connect emergency abandonment and recovery rigging to the A&R cable and to the emergency laydown head whilst the laydown head still forward the tension machine at beadstall. Ref Dwg No. 16009-AMC-OPS-DWG-408-00 “12’’ Abandonment & Recovery Rigging Arrangement (S-Lay Mode) in Appendix 2.
  • Transfer the load from tension machine to A&R winch when the emergency laydown head is just forward the tension machine.
  • Continue to move vessel forward maintaining the A&R tension.
  • LCE movement can be stopped when the emergency laydown head is on seabed.  The emergency laydown head will then can be lowered down safely.  Record position and heading of the barge. Ref Dwg No. 16009-AMC-OPS-DWG-359-00 “12’’ Pipeline Laydown Abandonment and Recovery Sequence” in Appendix 2.
  • Depending on the weather, ROV may be called to monitor the abandonment progress and take fix of the emergency head.
  • If ROV is unable to dive, record the vessel position when the emergency laydown head is at the barge stern. This will serve as approximate position of the laydown head during recovery process.
  • In case the LCE needs to leave from site due to bad weather, ROV may call to make a cut on sacrificial sling. If ROV is unable to dive, the A&R wire can be cut as close to the spelter socket as practical.
  • Refer to the analysis report [Ref 50] for Abandonment Analysis.

Pipeline Recovery

Following guideline is step-by-step procedure for pipeline recovery:

  • Position the barge such that the expected emergency laydown head location is about 5 – 10m from stinger tip. Lower down A/R cable through stinger tip.
  • Launch the ROV for hook up the recovery sling
  • ROV grasp ROV hook to hook it up to recovery sling on pulling head.
  • Position the barge heading and location the same as per the abandonment process. The A&R cable must be slack at all time during this operation.
  • Gradually increase the tension in the A&R winch in accordance with the recovery tension [Ref 50]
  • Move back the vessel whilst the A&R winch paying in so that the tension in the A&R cable is constant. ROV to monitor the recovery process.
  • When the emergency laydown head pass the aft tension machine, activate the aft tension machine.
  • Transfer the load from A&R winch to aft tension machine.
  • Continue to move barge backward maintaining the tension in the tension machine until the pulling head pass the fwd tension machine.  Activate the tension machine. Continue to pull in on the A&R winch maintaining zero tension on the cable.
  • When the emergency laydown head is at the bead stall, barge movement can be stopped. Remove the A&R cable and the shackle from the emergency laydown head.
  • Cut the emergency laydown head.  Re-bevel the pipe, and continue with normal pipelay.
  • Refer to the analysis report [Ref 50] for Recovery Analysis

Wet & Dry Contigency Procedure

Dry Buckle

During pipelay operation, the ROV will be utilized to monitor the condition of the pipeline from stinger to touchdown. If the dry buckle has been found over the stinger section or between stinger tip and touchdown, a decision will be made by OCM after consulting with COMPANY & CONTRACTOR CSR to either recover the pipeline over the stinger and past the tensioners or to lay down.

Note: If the pipeline will be laid down on the seabed, wet buckle procedure will be applied. If the damaged section can be safely recovered over the Stinger and into the tensioners, the following procedure will be applied.

  • Remove internal pipeline equipment from pipeline interior, if required.
  • Tension machines will be used to pull the pipeline back whilst the vessel is being backed until the buckled joint is just aft of the tensioning machines. Successive joints from the pipeline to be removed and re-beveled.
  •  Emergency laydown head will be welded to the pipeline and connected to the A&R winch.
  •  Pipeline tension will be transferred from tensioner to A&R winch.
  •  A&R winch will pull the pipeline damaged section through the tensioners until damaged section is forward of tensioners.
  • Transfer pipelay tension from A&R winch to tensioner and disconnect A&R winch wire from emergency head.
  • Remove emergency laydown head and re-bevel pipeline end.
  • From step 2-7, at OCM’s discretion, the pipeline might be pulled till damaged section forward of tensioner by utilizing 2 of 3 tensioners at a time.
  • Internal pipeline equipment will be re-inserted (if required) and normal pipelay operations will commence. This is only permissible if agreed to by CSR.
    Note: All overstressed and damaged pipes will be discarded.

Wet Buckle

During pipelay operation, ROV also be utilized to monitoring the condition of the pipeline from the stinger tip to touchdown point. If the wet buckle occurs, a sudden increase in tension and stinger load will be experienced. The severity of the wet buckle will be evaluated using the ROV and a decision will be made to lay the pipeline down. If recovery is considered safe, dry buckle procedure shall be applied. If the pipeline is to be abandoned, the below procedure can be applied.

FE will check the following parameters and comparing with the analysis to confirm wet or dry buckle:

Water Depth

Lay Tension

Maximum Load on the Stinger Roller

Upon completion of preliminary check that the wet buckle has occurred, the pipeline needs to be abandoned.

In the event of an abandoned pipeline due to wet buckle, the following steps shall be followed to recover the pipeline. Note that the below steps shall serve as a guideline only and a specific detailed recovery procedure will be developed for pipeline recovery for wet buckle condition.

  •  When a wet buckle is experienced and it is determined that the pipeline needs to be abandoned. The below step will be taken after wet buckle recovery equipment & personnel are mobilized.
    Notes: Upon completion on incident investigation associated with wet buckle, LCE will proceed to next installation activity in the program. Meanwhile onshore team will mobilize the necessary equipment to recover the pipeline.
  • LCE and ROV survey support vessel to the damage pipeline location and deploy ROV to inspect the extent of the damage
  • LCE to relocate @ KP 0.0 at LH34 Side
  • Recover 12’’ pipeline in J-Lay mode and install PLET 8
  • Relocate LCE to damage location
  • Deploy ROV with diamond cutting tool to cut out the buckle section of pipeline.
  • The abandon pipeline section (with the damaged joints) will be recovered from seabed.
  • Pipeline Recovery Tool (PRT) will be deployed and inserted into pipeline end by the ROV guidance. Ref Dwg No. 16009-AMC-OPS-DWG-367-01 “12’’ Pipeline Wet Buckle Repair Sequence” in Appendix 2.
  • De-water 12’’ pipeline from PLET 8 by Survey ROV vessel
  • Push pig until it reaches the PRT
  • LCE A & R cable will be deployed through the stinger with ROV hook and hook-up to PRT by ROV guidance. The sequence will be as per pipeline recovery sequence in previous section. Ref Dwg No. 16009-AMC-OPS-DWG-367-02 “12’’ Pipeline Wet Buckle Repair Sequence” in Appendix 2.
  • Continue normal pipelay.

Pipeline Recovery @ KP 0.00 CRA End

12” Recovery in JLay Mode @ KP 0.00 CRA End

Step-by-step procedure for 12” Recovery in J-Lay Mode at KP 0.00 is outlined in the below table;

  • Status:
    – Project brief completed.
    – Toolbox talk has been conducted with all personnel involved in the operation.
    – Perform communication check prior to operation commencing including but not limited to: bridge, shift supervisor, deck foreman / barge foreman, crane operator.
    – A & R wire  &109mm rerouted through the A-Frame Sheave with the open spelter socket re-instate
    – A&R Frame adjusted to the required angle
    – Work platform is fully retracted
    – Spider clamp is installed and rigged up on work platform and spider clamp door is fully open and secured.
    – Air tugger is installed A-Frame vicinity
    – Survey Vessel is at standby position on the LCE port side.
    – ROV deployed on Survey Vessel and standing by in water
    – Completed general deck preparations for welding, cutting, i.e. function check
    – All survey data is displayed on vessel navigation screen.
    – PTW in place.
    – Weather Forecast has been assessed for installation window.
  • Set-up LCE with the A-Frame directly above to the laydown head to the partially laid  12’’ pipeline @ KP 0.00 Ref Dwg No. 16009-AMC-OPS-DWG-371 “12’’ Pipeline J-Lay Mode Recovery @ KP 0.00” in Appendix 2.
  • Lower A&R wire to the sea bed with ROV hook while ROV to monitor winch wire
  • Once ROV hook is at sea bed, position the ROV hook to the laydown rigging by moving the vessel
  • ROV to connect hook to laydown rigging
  • Start to pick up slack on laydown rigging by paying in A&R wire and all stop
  • Start recovering pipeline in J-Lay mode by moving the vessel and paying in the A&R wire according to the analysis report [Ref 50].
  • ROV to monitor recovery the 12’’ pipeline process
  • Continue to pay in A&R wire until the 12’’ pipeline is above the work platform height and all stop
  • Extend work platform until the 12’’ pipeline slides into the work platform opening
    Note: Air tugger can be used to assist to pull in the 12’’ pipeline into the platform opening or move vessel towards port
  • Activate the spider clamp and secure the 12’’ pipe below the A&R head. Ref Dwg No. 16009-AMC-OPS-DWG-373-01 “Head Replacement Sequence @ KP 0.00
  • Close the spider clamp door and insert lock pin on spider clamp support frame
  • When load is fully transfer to spider clamp, hold 12’’ pipe with A&R wire for 5 minutes to monitor if there is any slippage on the spider clamp
  • Disconnect A&R wire from laydown head
  • Retrieve A&R wire until the spelter socket is at the A-Frame sheave

12’’ Head Removal and Laydown in J-Lay Mode @ KP 0.00 CRA End

Step-by-step procedure for 12” Head removal and laydown in J-Lay Mode at KP 0.00 is outlined in the below table;

  • Status:
    – Project brief completed.
    – Toolbox talk has been conducted with all personnel involved in the operation.
    – Perform communication check prior to operation commencing including but not limited to: bridge, shift supervisor, deck foreman / barge foreman, crane operator.
    – Completed general deck preparations for welding, cutting, i.e. function check
    – 12’’ pipe is resting on spider clamp
    – All survey data is displayed on vessel navigation screen.
    – PTW in place.
    – Weather Forecast has been assessed for installation window.
  • Install cutting tool to J-Lay laydown head
  • Connect crane to J-Lay laydown head  
  • Cut J-Lay laydown head and recover to deck by crane (weight of J-Lay Head = 1 MT) 
  • Crane to pick up new S-Lay laydown head and slew towards A-Frame (weight of S-Lay Head = 1 MT) 
  • Line up S-Lay laydown head to the 12’’ pipeline using external line up clamp 
  • Weld S-lay laydown head and NDT weldment. [Ref 42][Ref 46] 
  • Connect A&R wire with ROV hook to S-lay laydown head rigging
  • Pick up slack on laydown rigging by paying in A&R wire
  • Slowly transfer spider clamp load to A&R wire   
  • Once load is transfer, de-activate spider clamp and open spider clamp door
  • Re-tract work platform  
  • Start lowering pipeline in J-Lay mode by moving the vessel and paying in the A&R wire.
  • ROV to monitor the 12’’ pipeline lowering process 
  • Once S-Lay laydown head is on sea bed, ROV to disconnect ROV Hook 

12’’ Recovery & Laydown in S-Lay Mode @ KP 0.00 CRA End

Step-by-step procedure for 12” Recovery and laydown in S-Lay mode at KP 0.00 is outlined in the below table;

  • Status:
    – Project brief completed.
    – Toolbox talk has been conducted with all personnel involved in the operation.
    – Perform communication check prior to operation commencing including but not limited to: bridge, shift supervisor, deck foreman / barge foreman, crane operator.
    – 12’’ pipeline laid down
    – A & R wire  &109mm rerouted through the firing line until stinger end with the open spelter socket re-instate
    – Survey Vessel is at standby position on the stern.
    – ROV deployed on Survey Vessel and standing by in water
    – Completed general firing line preparations for welding, cutting, FJC and etc. i.e. function check
    – All survey data is displayed on vessel navigation screen.
    – PTW in place.
    – Weather Forecast has been assessed for installation window.
  • Set-up LCE stinger above the laydown head @ KP 0.00 
  • Lower A&R wire to the sea bed with ROV hook while ROV to monitor winch wire
  • Once ROV hook is at sea bed, position the ROV hook to the laydown rigging by moving the vessel 
  • ROV to connect hook to laydown rigging 
  • Start to pick up slack on laydown rigging by paying in A&R wire and all stop
  • Start recovering pipeline in S-Lay mode by moving the vessel and paying in the A&R wire according to the analysis report [Ref 50]. 
  • ROV to monitor recovery the 12’’ pipeline process.
  • Continue recovering pipeline using the A&R winch until laydown head pass all tensioners. Transfer tension from A&R winch to tensioners.  
  • Disconnect A&R wire from head
  • Remove S-Lay Head at the Carbon Steel /Clad pup piece
  • Transfer the hang-off CLAD collar joint section into tunnel and weld to the pipeline at beadstall [Ref 27]. 
  • Weld the Carbon Steel /Clad pup piece to the collar [Ref 27].
  • Weld the laydown head to Steel /Clad pup piece. Ref Dwg No. 16009-AMC-OPS-DWG-373-02 “Head Replacement Sequence @ KP 0.00
  • Complete NDT for the collar weldment [Ref 27] & HSS application
  • Install collar protector at the collar section. Ref Dwg No. 16009-AMC-OPS-DWG-108-00 “12’’ Collar Protector” in Appendix 2.
  • Install laydown riggings and A&R cable. Note: Sacrificial and recovery riggings shall be paint white or other high visibility color for ROV to see underwater.
  • Continue move vessel forward till the pulling head is close to bow tensioner.  Then take up load on A&R while open bow and stern tensioners.
  • Slowly payout with tension of A&R winch till laydown head is under water.  ROV to be deployed to monitor laydown head passing stinger and elevation depth. Refer to the analysis report [Ref 50]. 
  • Keep payout whilst maintain tension till laydown head touchdown on seabed.  ROV to temporarily take fix on the pulling head and hang-off collar. 
  • If there is not much deviation in position with respect to the target box, move LCE astern. ROV to take fix again to re-confirm compliance of the installation tolerance. 
  • LCE to move backwards till stinger tip is above laydown pulling head is. ROV to perform sacrificial wire cutting. 
  • After cutting-off sacrificial wire, recover A&R winch wire to surface. 

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