Pipelay Procedure Revised

TABLE of CONTENTS

1

INTRODUCTION

4

1.1

General

4

1.2

Objective

4

1.3

Definitions and Abbreviations

4

1.3.1

Definitions

4

1.3.2

Abbreviations

4

1.4

References

6

1.4.1

Codes and Standards

6

1.4.2

COMPANY Documents

6

1.4.3

CONTRACTOR Documents

6

2.0

RESPONSIBILITIES

7

2.1

Project Manager

7

2.2

Construction Manager

7

2.3

Operations Manager

7

2.4

Lay Barge Superintendent

7

2.5

Lay Barge Master

7

2.6

Offshore Field Engineer

7

2.7

Quality Control Inspector

7

2.8

Safety Officer

7

2.9

Survey Party Chief

7

2.10

Dive Supervisor

8

2.11

Welding Supervisor

8

2.12

NDT Supervisor

8

2.13

FJC Supervisor

8

3.

HES REQUIREMENTS

9

3.1

Safety Policies

9

3.2

Risk Assessment

9

3.3

Security Plan

9

4.0

MAIN PIPELAY EQUIPMENT

10

4.1

Tensioner

10

4.2

A&R Winch

10

4.3

Stinger

10

4.3

General Specification of Jascon 2 Pipelay/Accommodation Barge.

10

1

5.0

LAY BARGE CONSTRUCTION ACTIVITIES

13

5.1

Pipeline Alignment

13

5.2

Barge Movement

13

5.3

Pipeline Profile

13

5.4

Barge Roller Settings

13

5.5

Applied Tension

14

5.6

Roller Box Settings

14

6.0

PIPELINE INSTALLATION DATA

14

6.1

Overview/General Features

14

6.2

Pipeline Parameters

14

6.3

Environmental Data

14

7.0

PIPELAY OPERATION

15

7.1

Pipeline Parameters

15

7.2

Mobilization

15

7.3 Demobilization Bookmark not defined.

Error!

7.4

Start-Up/Initiation for Pipeline

15

7.4.1

Hang and Initiate

15

7.4.5

Continue the pipeline after beach pulling.

16

7.5

Normal Pipe lay Sequence

16

7.6

Laydown Operations

17

7.7

Abandonment & Recovery

18

8

PIPELINE CONTINGENCY PROCEDURE

19

8.1

Bad Weather

19

8.2

Buckle Detection - General

20

8.3

Buckle Repair - General

20

8.4

Dry Buckle Recovery Procedure

21

8.5

Wet Buckle Recovery Procedure

21

8.6

Stinger Failure

22

8.7

Tensioner Failure

22

8.8

Support Tug Breakdown

22

9

WORK PLAN

23

Work Plan 001:

23

Pre-Mobilization

23

Work Plan 002:

24

Mobilization

24

Work Plan 003:

25

Initiation Operations

25

Work Plan 004:

28

Normal Lay Operations

28

Work Plan 005:

30

Laydown Operations

30

ATTACHMENTS BOOKMARK NOT DEFINED.

ERROR!

ATTACHMENT A Bookmark not defined.

Error!

Ramp and Stinger Configuration Drawing (2 Sheets) Bookmark not defined.

Error!

ATTACHMENT B Bookmark not defined.

Error!

Typical Anode Installation Drawing Bookmark not defined.

Error!

ATTACHMENT C Bookmark not defined.

Error!

Typical Pipeline Initiation Drawing – Hang & Initiation Method Bookmark not defined.

Error!

ATTACHMENT D Bookmark not defined.

Error!

Typical Pipeline Initiation Drawing – DMA Method Bookmark not defined.

Error!

ATTACHMENT E Bookmark not defined.

Error!

Typical Pipeline Initiation Drawing – Sheave Method Bookmark not defined.

Error!

ATTACHMENT F Bookmark not defined.

Error!

Typical Pipeline Initiation Drawing – Bow String Method Bookmark not defined.

Error!

ATTACHMENT G Bookmark not defined.

Error!

Typical Pipelay Sequence Drawing Bookmark not defined.

Error!

ATTACHMENT H Bookmark not defined.

Error!

Typical Abandonment & Recovery Drawing Bookmark not defined.

Error!

1 1.1

INTRODUCTION General

Pipelay operation during subsea pipeline construction can be accomplished using a range of pipelay methods; the single method to be engaged for a particular pipelay project depends on the company‟s specification which is detailed in the pipelay operational procedure. The installation procedure shall cover the pipelay project scope and identifies all tasks, information and equipments required for the successful achievement of the pipelay operations. The pipelay approved manual shall be adhered to in executing all pipelay activities. All construction activities carried out are to be recorded by contractor for post job as-built documentation that will be submitted to company. In this document, West African Ventures Limited shall be referred to as „‟CONTRACTOR‟‟ and the project owner shall be referred to as „‟COMPANY‟‟. 1.2

Objective

This general procedure is to present an overview of activities relating to pipelay using S-Lay barge and technical data required to accomplish installation of the pipelines including the procedures for abandonment and recovery. This procedure will be used by project personnel on board of the pipelay barge to ensure all activities regarding pipe laying are performed in accordance with the COMPANY‟S master specifications, CONTRACTOR‟S approved quality, Health, Environment & Safety (HES), operational procedures, guidelines and standards. The scope of the project will provide a review of the methods surrounding the activities for the pipe laying operations during offshore construction. The operations to be covered in this procedure are as follows: initiation operation, normal pipe lay operation, lay down operation and abandonment and recovery.

1.3

Definitions and Abbreviations

1.3.1

Definitions

CONTRACTOR

West African Ventures Limited

COMPANY

TBA

SUB-CONTRACTOR

Entity engaged by CONTRACTOR to perform part of the work to the extent permitted.

1.3.2

Abbreviations

A&R

Abandonment and Recovery

AHT

Anchor Handling Tug

ACC

Anti Corrosion Coating

API

American Petroleum Institute

ASME

American Society of Mechanical Engineers

BT

Bottom Tension

DMA

Dead Man Anchor

FJC

Field Joint Coating

HES

Health, Environment & Safety

HSS

Heat Shrink Sleeve

ID

Internal Diameter

MBL

Minimum Breaking Load

MWS

Marine Warranty Surveyor

N/A

Not Available

NDT

Non Destructive Testing

NPS

Nominal Pipe Size

OD

Outside Diameter

OOD

Overall Outside Diameter

SMTS

Specified Minimum Tensile Stress

SMYS

Specified Minimum Yield Stress

SWL

Safe Working Load

TBA

To Be Advised

TT

Top Tension

WPS

Welding Procedure Specification

WT

Steel Wall Thickness

TBN

To Be Numbered

RAO

Response Amplitude Operating

CCTV

Close Circuit Television

1.4

References

The following documents were consulted as references in developing this procedure. 1.4.1

Codes and Standards

DNV-OS-F101 1.4.2

Submarine Pipeline System(DNV 2000)

COMPANY Documents

TBA 1.4.3

CONTRACTOR Documents

WAV-PR-05-001

Engineering Control Procedure

WAV-PR-GE200-012

Security Plan

WAV-PR-GE200-014

Safety Plan

WAV-PR-GE200-015

Emergency Preparedness and Response Plan

WAV-PR-GE200-017

Risk Assessment and Management Plan

WAV-PR-GE016-001

Management of Change

TBN

Pipelay Analysis Report

TBN

Alignment Sheets

TBN

J2 Anchor Pattern

2.0

RESPONSIBILITIES

The responsibilities specific to the Pipeline installation are listed below. 2.1

Project Manager

Project Manager is the overall responsible person for the project and shall be the primary point of contact between CONTRACTOR and COMPANY for all communication. Project Manager supervises all activities and ensures that project material procurement is carried out. He initiates the project kick-off meeting onboard. 2.2 Construction Manager Construction Manager has overall responsibility for all marine construction activities, personnel and equipment with CONTRACTOR. 2.3 Operations Manager Improve the operational systems, processes and policies in support of organizations mission specifically, support better management reporting information flow and management business process and organizational planning. 2.4


The Lay Barge Superintendent is responsible for the execution of the project in the field. The Lay Barge Superintendent directs all project personnel and construction crew and represents CONTRACTOR and liaises with the Client representative in the field. The Lay Barge Superintendent reports to the Project Manager and also liaises with the Barge Master with respect to marine affairs. 2.5

Lay Barge Master

The Lay Barge Master is responsible for the safety of the barge, its crew and all personnel onboard. The Lay Barge Master has the responsibilities and powers as vested in him by IMO. The Lay Barge Master provides support to the Lay Barge Superintendent to effectively execute the work. They are responsible for all marine activities, such as barge positioning and directing all barges and marine craft in the field that are mobilized for the work. 2.6


The Offshore Field Engineer supports the Lay Barge Superintendent on all technical matters pertaining to the work. He monitors whether the work is carried out as per the procedures and in accordance with the technical specifications. Where deviations are necessary, he assists the Lay Barge Superintendent in planning and where additional engineering is required, he liaises with the Sr. Project Engineer based in the office. 2.7

Quality Control Inspector

The Quality Control Inspectors are responsible for the quality of the work. They are responsible for the administration of all quality control documents, pipe tally sheets, as-built and other project documents. They ensure that certificates and tags of project materials are in place. They report to the Lay Barge Superintendent and QA/QC Manager. Where they find substandard work this is reported. 2.8

Safety Officer

The Safety Officer is responsible for all safety matters pertaining to the project activities on board. He coordinates the permit to work system if required and conducts safety induction. He reports to the Lay Barge Superintendent and HES Manager and assists the Lay Barge Master in carrying out safety activities such as drills onboard the barge. 2.9

Survey Party Chief

The Survey Party Chief assists the Lay Barge Master with the positioning of the barge. He advises the Lay Barge Master on all seabed features and other topographical details that may be a hazard. He is responsible for the proper functioning of the positioning systems used on the project.

2.10

Dive Supervisor

The Dive Supervisor represents the diving subcontractor. He is responsible for implementing the diving procedure where diving activity is required. He is responsible for safety of the diving personnel and for integrity of the equipment. Dive Supervisor shall ensure compliance with industrial standard and requirements. He reports to the Lay Barge Superintendent. 2.11

Welding Supervisor

The Welding Supervisor manages the welding. He is responsible for directing the welding personnel and manages all welding activities on the barge. 2.12

NDT Supervisor

The NDT Supervisor represents the NDT subcontractor. He is responsible for inspection of welds and maintaining the inspection documents in a proper manner. He advises whether repairs or cut outs are required. He reports to the Lay Barge Superintendent. Details of the plans and procedures related to NDT will be supplied by the NDT subcontractor. The document will be available for review by COMPANY. 2.13

FJC Supervisor

FJC will be carried out and experienced supervisor will be appointed, who will be in charge of the activities planned and ongoing related to the application of the field joint coating. He reports to the Lay Barge Superintendent.

3.

HES REQUIREMENTS

3.1 Safety Policies CONTRACTOR shall comply with COMPANY HES rules, regulations, procedures, and policies such as: alcohol and drug policy, transport policy, environmental compliance, emergency response, incident reporting, PPE regulations, medical and trainings, audit and inspection risk assessment, jsa, hazard identification, toolbox meetings, safety meetings etc. In addition to the above conditions the project team shall aim to; 1. 2. 3.

achieve zero accident during all offshore operations, perform weekly HES inspection, eliminate / reduce unsafe conditions / acts at the project site.

Activities to be carried out during Mobilization shall include lifting, inspection, and equipment testing etc. All operations shall be carried out in a safe and responsible manner. Safety policies and safe practices shall be considered at all time. All new personnel to offshore locations shall be given a tour round the vessel and introduced to the safety features as required. Fire and lifeboat drills shall be held at frequent intervals, regular safety meetings shall be held, and minutes of such meetings kept on board throughout the duration of the work. Personnel shall actively participate in schemes designed to enhance theirs and everybody else‟s health and safety onboard the vessel. A boat and fire muster drill shall be held within 24 hours of departure from the port and on a weekly basis at the location. Prior to every operation, toolbox talk shall be convened. This shall be attended by all personnel concerned with the operation and shall assess whether all the factors required from the operation risk assessment are in place and if the circumstances offshore at the time of operation shall require MOC to be used, and plan for the day‟s work. A record shall be kept of all safety related issues during the project. The respective safety and environmental measures, described in CONTRACTOR‟s Safety, Health, Environment and Security Plan shall be implemented. With respect to possible fuel spills, drip pans and absorbent materials shall be on hand foreseen. Waste shall be properly segregated and stored at a designated area on deck following the sludge and garbage disposal procedure as described in the Project Safety, Health, Environment and Security Plan. Collection of waste shall be registered and shall be collected on a regular basis. 3.2

Risk Assessment

All operations to be carried out shall be in accordance with Nigerian legislation and approved procedures. A CONTRACTOR in-house Risk Assessment shall be undertaken before any offshore operation in accordance with Risk Assessment and Management Plan (WAV-PR-GE200-017). Risk assessment shall review all activities in the operation and highlight areas that require further action that should address safety in completing the task without loss of live or property (safety plan WAV-PR-GE200014) 3.3

Security Plan

Security shall be provided in accordance with the Project Security Plan as it applies in both onshore (for the beach site) and offshore (for the barge) operations (WAV-PR-GE200-012 Security Plan). 3.4

Management of Change

If during this operation, it is discovered that the existing procedure is inadequate and requires modification due to an additional or unplanned item of work, then reference should be made known to management for the change requirements in the procedure. Any change that is carried out shall be in accordance with Change Control / Management of Change Procedure (WAV-PR-GE016-001). 4.0

MAIN PIPELAY EQUIPMENT

The functionality of the pipe lay installation equipment and capability of Jascon 2 which is S-lay barge has been demonstrated in the Jascon 2 Seatrial. The relevant boundaries of the interface between the pipe lay equipment installed and the Lay barge capability is described below. 4.1

Tensioner

The Lay barge is equipped with one tensioner vertically positioned and capable of providing a maximum tension of 25mT with an adjustable dead band setting. The tensioning unit applies continuous horizontal pulling force to the Pipe. The capability of the tensioner to function properly has been verified during the sea trials campaign. 4.2

A&R Winch

The abandonment and recovery winch of Jascon 2 will be utilized for Termination, A&R operations. The capacity of the A&R winch would have been load tested and calibrated. 4.3

Stinger

The fixed geometry stinger for the lay barge Jascon 2 has a length of 35.5m detachable at 23.55m. The stinger is suspended from an A-frame. With this A-frame the stinger inclination is controlled. The pipeline curvature on the barge and stinger is controlled by adjusting the rollers heights. By adjusting the stinger inclination it is ensured that the transition between the pipe curvature on the barge and stinger will be smooth. Refer to ATTACHMENT A for the Stinger arrangement Drawing. OFFPIPE program will be used to determine the settings of the pipe lay equipment are well within the design requirements for the project. OFFPIPE Engineering analysis will cover, as a minimum, the following procedures for the pipeline construction to be performed by the lay barge.

#

Name of Run

1

Initiation Analysis

2

Normal Lay Analysis

3

Abandonment and Recovery Analysis

4

Davit Lift Analysis

4.3

Water Depth

Pipe Size

Pipe Status

General Specification of Jascon 2 Pipelay/Accommodation Barge.

The list below illustrates the general specification of Jascon 2 pipelay and accommodation barge. General Delivery

2009

Classification

Bureau Veritas, Pipelay / Construction Barge

Flag

St. Vincent & the Grenadines

Port of Registry

Kingstown

Dimensions Length, overall Breadth Depth Max. Operating draft

74.0 m 35.35 m 4.7 m 3.0 m

Machinery Power generation Deck generators

2 X Cummins Pipeline Generator, 888 kW, 60Hz 1 x Perkins, 400 kW, 50Hz and 1 x Cummins, 440kW, 50Hz

Mooring System 8-point mooring system Anchors

4 x 45.5T AMHOIST Air Controlled double drum winches with 1,200m of 38mm diameter wire rope 8 units Flipper Delta 5T

Pipelay Equipment Concept

Starboard side mounted single joint S-lay system

Capacity

Able to lay from 6” up to 32” Dia. linepipes.

Tensioners

1 SAS Tensioner - 25T

Workstations

3 welding stations, 1 NDE station (X-ray or Ultrasonic) / repair Station and 1 coating station; all stations sheltered.

Stinger

Length: 35.50m, Roller beds: 3, Stern Roller: 1

A-Frame Winch:

130T, 730m cable

Davits

4 Nos x 35T mounted with load cells at Starboard,

Cable Length

220m

A & R System

A & R winch SWL 25T located at deck level, 500m x 38mm wire

Cranes Main Crane

Huisman crane 300T SWL

Main hoist

300T @ 11 m working radius / 9 Falls

Aux. hoist

30T

Starboard side Crane

TTS - 45T @ 35m, 34T @ 4.2 – 20m, 22T @ 4.2 – 30m 5T @ 4.4 – 31m

Accommodation 230 persons broken down into single, 2, 4, 6 and 8 men air-conditioned cabins. There are also laundry, dry/cold stores, changing rooms, TV rooms and recreation facilities. Supplemental facilities include offices, Chief Client Representative Office and Executive room, VIP rooms, Client rooms and offices, Helicopter arrival/departure lounge, Safety/Security Office and a Clinic with separate treatment room etc. Helideck Suitable for Sikorsky S92A Helibus. Galley / Mess-hall Spacious and air conditioned Seating Capacity:

64 Persons

Auxiliary Equipment Sewage treatment incl. vacuum system Watermakers, RO type, 2 x 60 t /day Helideck foam system Pumps Compressors HVAC Refrigeration plant Air tuggers Navigation and Communication Equipment 2 x Radar 1 x Weather facsimile Navtex Satcom Fixed VHF GMDSS Radio Epirb Portable VHF Aviation Radio Fix VHF Aviation Radio GPS Workshops Fully equipped mechanical and electrical workshops. Safety Equipment Life rafts for 300 persons One fast rescue boat: Brand: Normar – Rescue 425, Capacity – 6 persons, Powered by: TOHATSU 18.4 kW Engine Life jackets, life buoys, firemen‟s outfits, Heli rescue equipment Fire extinguishers CO2 system generator rooms Fire detection system Additional Info Fuel Tank Capacity: (562m3), (562,000 Liters), (148,467 US gal) Water Tank Capacity: (1300 m3), (1,300,000 Liters), (343,423 US gal)

5.0

LAY BARGE CONSTRUCTION ACTIVITIES

The information given in this section is general and intended, where applicable, to relate to all phases of the pipeline construction. Detailed and specific procedures relevant to each pipeline and construction activity are presented in the subsequent procedures. Changes to pre-approved procedures shall be documented using an established Management of Change process. Where appropriate the document may be revised in the field and re-issued. 5.1

Pipeline Alignment

The pipelines will be installed in the designated routes, as per Company‟s Specification, by using the barge anchor system to position the lay barge and the initiation system from the platform or by means of DMA system such that the touchdown point of the pipeline on the seabed is in the designated route. The barge maintains continuous survey positioning while laying the pipelines to ensure the lines are positioned within the planned corridor. The barge position is over/under compensated through the curve as estimates of the pipe touchdown resulting from the pipelay analysis help determine the barge route to ensure the pipeline lays adequately within the corridor with careful consideration of pipelay tolerance as specified in the Company‟s Specification. Pipeline routing shall be in accordance with the Company‟s approved alignment drawings. 5.2

Barge Movement

Once construction activities at the last workstation on the lay barge are completed, the lay barge advances for a nominal pipe joint to relocate the joints at the subsequent workstations and allows the addition of next joint of pipe to the pipeline. The lay barge is held on location by at least eight anchors, which are frequently relocated, as required, to provide adequate restraint for pipeline tensioning and security of the barge position. 5.3

Pipeline Profile

At completion of the pull at each section of pipeline, the lay barge proceeds to install pipe in a conventional manner. Pipelay operations will continue until the pipeline reaches the lay down point in the target area. Normal pipelay operations require the pipeline to be deflected in an S-curve shape from a horizontal position on the lay barge through a downward curve into the water that is then reverse curved back to horizontal at the seabed. The top portion of the S-curve, the over bend, is controlled by roller supports on the barge and the stinger. The lower portion of the S-curve, the sag bend, is controlled by the application of a horizontal force to the pipeline, which controls the shape of the S-curve. See attachments C, D, E & F (Pipelay Initiation Drawings). 5.4

Barge Roller Settings

Pipeline geometry on the barge is controlled by roller supports. Rollers located throughout the pipe alley support the pipeline. The respective heights of these rollers will be determined during installation

engineering and may be adjusted during pipelay operations. See attachment A (Ramp and Stinger Configuration Drawing). 5.5

Applied Tension

Pipeline geometry is also controlled by the applications of a vertical force to the pipeline. The tensioner is arranged in a vertical order with the pipeline positioned between rollers shoes. The tensioner applies a continuous tensioning force to the pipeline by action of tracks pressed against the pipeline. These tracks apply a continuous controlled pulling force on the pipeline. See attachment G (Typical Pipelay Sequence Drawing). Minimum tension settings for the pipeline over the anticipated water depth ranges will be determined from the pipe lay analysis report. 5.6

Roller Box Settings

The stinger angle will be set with respect to the pipe lay installation analysis report; the stinger will be supported by the hinge on the lay barge hull and the A-frame of Jascon-2 lay barge. Please refer to ATTACHMENT A for Stinger and Roller configuration drawing sheets showing settings for Pipe lay. Please, note that the X-coordinate is referenced from the stern (0 at barge stern) and the Y-coordinate is directed vertically up from barge deck (0 at barge deck). 6.0 6.1

PIPELINE INSTALLATION DATA Overview/General Features

Following parameters are to be addressed in scope for pipelay. These include but not limited to: 1.

total length of pipeline to be laid.

2.

the relevant KP as per the scope of work.

3.

water depth along the route.

4.

crossing details.

5.

maximum lay tension encountered.

6.2

Pipeline Parameters

Typical pipeline parameters are as shown below in Table 6.1: Table 6.1 Pipeline Parameter Pipe Data

6.3

1

Pipe Diameter

2

Pipe Wall Thickness

3

Pipe Grade

4

Pipe Yield Strength

5

Pipe Corrosion Coating Thickness

6

Pipe Concrete Coating Thickness

7

Pipe Concrete Coating Density

Water depth

Environmental Data

The pipelay analysis is performed using the allowable strain criteria. The pipelay operation is allowed only when the weather condition maintains within acceptable criteria. The seastate values will be extracted from metocean data provided by COMPANY and are to be applied for directions 0 to 180 degrees in sectors of 45 degrees using the Vessel RAO data.

In general, Initiation, Abandonment & Recovery, and Lay down shall be conducted within the range of the acceptable weather condition. 7.0 7.1

PIPELAY OPERATION Pipeline Parameters

The relevant parameters applicable to the pipeline to be installed for the project are detailed below: 

Total pipeline length to be determined as per CONTRACTOR proposed preliminary route plan issued for COMPANY Approval.



Along the pipeline route, crossing will be taken care of by means of pre-installed separation mattresses or concrete sleepers to cross over this will depend on the crossing design.

7.2

Mobilization

Mobilization will take place prior to the start of the project. For more details on project mobilization, reference is made to WAV document “Mobilization Plan” (WAV-XX-XX-XXX). The mobilization includes but not limited to the following: 

Issuing all relevant documentation to all parties involved prior to start of the project according to the project distribution list.



Preparing Jascon 2 for project related marine/construction activities. This will involve amongst others setting the stinger, roller boxes and tensioner.



Loading material/equipment required for the pipelay operations, including but not limited to the following: 1. Start-up and A&R/ Laydown rigging. 2. Welding consumables 3. Start-up and A&R/ Laydown heads. 4. Diving equipment 5. Survey equipment. 6. NDT equipment 7. Field joint coating equipment and materials 8. Welding, catering and project crew

7.3

Start-Up/Initiation for Pipeline

The pipe lay startup may be performed using any of the four initiation methods below:

7.3.1

1.

Hang and Initiate method.

2.

Dead Man Anchor/Pile method.

3.

Sheave method.

4.

Bow String method.

5.

Stack on riser method.

Hang and Initiate

The hanging initiation is carried out from the fixed offshore platforms. The initiation cable attachment point will be at a suitable pre-determined jacket leg/bracing (above or below the mean water line) nearest to the proposed riser location. A suitable size cable will be wrapped around the jacket leg and the initiation cable will be shackled to the wrapped cable.

The Pull-Head will be shackled to the start-up cable allowing the pipeline to initiate at a point near the mudline of the jacket leg. Pipe will be pushed off the stern of the barge allowing the start-up cable and startup head to be secured together. Typical drawing detail using the hanging initiation is found in Attachment C. 7.3.2

Dead Man Anchor/Pile

When the Hang and initiate procedure cannot be utilized, a dead man anchor shall be used to initiate the pipeline. The Deadman anchor shall be placed in a convenient location with the start-up cable pre-attached. The start-up head will be shackled into the start-up cable, allowing the pipeline to initiate at a point below the water surface. Pipe will be pushed off the stern of the barge allowing the start-up cable and start-up head to be secured together. Existing pipelines will be protected with concrete mattresses whenever initiation cables cross them. Typical drawing detail of DMA initiation is found in Attachment D. 7.3.3

Sheave Pulling

Another method of pipeline initiation procedure that may be used in this project is the use of a hold back cable and snatch block (Sheave) deployed near the jacket structure on the sea bed. The snatch block is connected by wrapping a suitably sized steel wire sling around the jacket structure with the aid of shackles. An anchor line is then run through the snatch block and the free end is connected to the initiation head of the pipe joints on the barge ramp. While joints are welded up, the pipe is pulled over the stinger and onto the seabed by the anchor line under controlled tension. After connecting the initiation head to the suitably sized steel wire using a hold back sling, the snatch block is recovered and the barge moves forward and pipelaying continues. It should be noted that the length of the hold back sling is usually field determined. Typical drawing detail of the Sheave Pulling initiation is found in Attachment E. 7.3.4

Bow-string Initiation

This method will be employed to avoid having a long start-up cable and to keep the end of the pipeline close to the jacket. This method involves the use of a suitably sized sling and shackle connections to parallel jacket legs or jacket bracings as site conditions may dictate. This sling is passed through a shackle on an intermediate sling serving as the start-up cable. The bowstring rigging is then attached to the initiation head as the pipeline protrudes past the end of the stinger. Once the rigging is completed, the lay barge will pull ahead gradually hence applying tension to the initiation string. Once the bowstring start-up tension is achieved, the laybarge will then continue the pipe laying stage. The weight of the start-up pull head and the pipeline, which is gradually increasing in length, causes the startup cable to slide down the bowstring until the end of the pipeline is resting on the seabed. Laying of the pipeline is continued carefully away from the jacket maintaining the required tension levels. Typical drawing detail of the Bow-string initiation is found in Attachment F 7.3.6

Continue the pipeline after beach pulling.

7.4

Normal Pipe lay Sequence

Prior to mobilization, pipe joints will be loaded onto the Jascon 2 in order to sustain 24-hour pipelay operations; offshore pipe loading will be required. This is done using a dedicated pipe supply barge coming alongside the Jascon 2 which transports the pipe from shore to the field. Pipe joints are loaded onboard the Jascon 2 to the pipe storage area using the Jascon 2 main crane. Once pipe joints are onboard the Jascon 2, the pipelay sequence of events is as follows: 

From the pipe storage area the pipe joint will be transferred to the conveyor house where it will be inspected, internally cleaned by removing any debris or loose particles. Upon acceptance of the joint by QA/QC joint bevel is prepared for welding.



From the conveyor house the pipe joints are transferred onto the line-up station for facing, welding and pipe joint numbering. Painted numbers are linked to the unique joint numbers for tracking purposes which will be reported as part of the as-built.



Upon completion of the welding passes of beadstall, welding station 1, pipe is pulled to welding station 2 and 3 respectively. Welding of pipe joints will be in accordance with CONTRACTOR document “Pipeline & Riser Welding Procedure”.



After completing the welding, the pipe is pulled through the tensioner to station number 4 which is the NDT/ repair station. NDT is carried out by means of RT; refer to CONTRACTOR document “NDT Procedures”.



After NDT, the pipe is pulled to station number 5 which is the coating station where the field joint is cleaned and pre-heated for anti corrosion coating.



Anti corrosion coating will be in accordance with CONTRACTOR document “Field Joint Coating & Repairs Procedure” and if required, foam application for FJC and forming.



Anodes will be installed at the coating station on predetermined joints as per joint sequence list. Cad welding of the anode conductivity cables takes place in the coating station. Anode installation will be in accordance with CONTRACTOR drawing “Typical Anode Installation Details”. Exact joint numbers with anodes will be indicated as part of the joints sequence lists to be drawn up onboard.



As each joint is added to the pipe string when a former joint is pulled to the stern, the complete pipeline will run down the stinger of the barge forming a caternary shape and subsequently will eventually land on seabed.



A camera located in the stinger will be used to monitor the pipe as it passes through the stinger. Tension applied to the pipeline will be continuously monitored utilizing a recording chart and controlled from the bridge to maintain the barge tensions within allowable limits.



The pipeline will with checked for coating defects with a holiday detector during pipelay. Repair materials will be available to repair areas of holiday.



Onboard survey SUBCONTRACTOR will direct the positioning of the barge throughout pipelay. The proposed pipeline route and corresponding barge track will be computed and interlinked with the barge navigation system to direct the position of the pipeline along the route.

7.5

Laydown Operations

Laydown operations consist of the following activities: 1. Determination of the final length of pipe 2. Completion of pipeline welding 3. Laydown pipeline 4. Confirm position of laydown head 5. Retrieve A&R cable The remainder of this section describes above lay down activities in more detail. 

Determine final length of pipe

On approaching the laydown point, the position of a minimum of 2 pipeline field joints on the seabed will be confirmed by means of transponders. The first transponder to be used will be at a field joint onboard when its position is at a minimum length of the layback plus tip gain plus 120m away from the proposed target box. The second transponder will be mounted adjacent to a field joint approximately the sum of layback tip gain and 60m away from proposed target box. All joints, lined up after the first transponder is measured. The length to the target box from a transponder is compared with the sum of joint lengths lined up and the final joint length required is determined. 

Complete pipeline welding

Depending on the calculated length of the final joint, it is either cut to length or prepared for welding, or it is lined up, welded to the pipeline and cut to length hereafter. After welding of the final joint, the internal pipelay equipment is removed and A&R/laydown head is lined up and welded to the pipeline. 

Laydown pipeline

Upon completion of welding of the laydown head, A&R cable is attached to the laydown head. Jascon 2 moves ahead until all slack is out of the A&R cable, tension is transferred from tensioner to A&R winch gradually and tensioner is opened. At this time, fire line shall be evacuated due to safety reasons. Laydown now commences by moving the barge ahead and paying out A&R cable in joint lengths as the last welds are tested and field joint coating is applied. For final positioning of the laydown head a transponder is strapped onto the pipe at the final weld. Normal lay characteristics are applicable until the laydown head approaches the stinger hinge. Hereafter the tension of the A&R winch tension is adjusted until the laydown head is at seabed. 

Confirm position of Laydown Head and A&R Cable Retrieval

Once the head is at seabed, barge holds position and slacks off the A&R cable. The position of the laydown head is confirmed by the transponder attached to it. Upon satisfactory confirmation hereof divers may approach the laydown head and cut the sacrificial sling. Hereafter A&R cable with sacrificial sling is recovered onboard and pipelay of the pipeline is completed. 7.6

Abandonment & Recovery

In case of interrupted pipelay activities due to weather or a component failure within the pipelay system, abandonment of the pipeline will be carried out. The Lay Barge Superintendent will decide if the pipe is to be abandoned and which procedure is to be followed. In case of an A&R the COMPANY representative will be notified and consent sought about proposed delay. Pipelaying will resume when the weather has improved or when the Pipelay equipment is operational again. Jascon 2 is equipped with A&R winch of 25mT capacity. Abandonment and Recovery is carried out according to the following process: a)

Abandonment

The activities applicable for abandonment are listed below:         

Remove internal pipelay equipment Line-up the A&R/laydown head and weld to pipeline Attach A&R/laydown rigging. Sacrificial sling may be omitted and A&R cable is connected directly to the shackle on the A&R/laydown head. Take slack out of the A&R cable and transfer tension from tensioner to A&R winch Pay-out A&R cable with same lay parameters as during normal lay Once the head is at stinger hinge, continue abandonment until the laydown head is on the seabed in accordance to the available table for A&R. Once the head is on the seabed, barge continues moving ahead approximately 100m with minimum cable tension. Barge moves backwards until cable as seen on stinger camera is nearly vertical If required stinger may be raised and barge turned into a favourable standby heading by pivoting relative to stinger tip.

It is anticipated that the pipeline will remain attached to the barge at all times. However, if under severe weather deterioration such that the laybarge will have to leave the field, A&R cable will be spooled off completely, connected to a messenger wire and abandoned with a surface buoy. During the spooling off of the A&R cable, barge moves ahead while maintaining a minimum tension in the cable. Alternatively, in a case of coiling reaction or possibility of cable knotting, the section will be cut off and re-pour the spelter socket as to save the bulk of cable on the drum. b)

Recovery

Once weather has improved or barge components have been repaired recovery of the pipeline may commence. The actual pipeline recovery is the exact reverse of abandonment. All values monitored during the abandonment will be observed during recovery. Upon completion of recovery, A&R head is inspected and reconditioned for the next A&R operation or laydown.

8 PIPELINE CONTINGENCY PROCEDURE This section describes the series of activities to be carried out in the event of any major anomalies, during the pipe laying. It describes the pipe laying contingency procedures, which are applicable to the lay barge Jascon 2 during the pipeline installation The various major anomalies that can occur during pipe laying include: 

Bad Weather



Buckle Detection



Buckle Repair – General



Dry Buckle



Wet Buckle



Stinger Failure



Tensioner Failure




This procedure should serve as a guideline for personnel and subject to minor site changes as prevailing site condition. The description of the above anomalies and the remedies to be undertaken are described below: 8.1

Bad Weather

The bad weather procedure will be initiated when the unloading of pipes becomes difficult due to heave motion of the vessels and/or critical sea-state for pipe laying. The pipe carrier is to be moved away from the lay barge even if the pipe unloading is incomplete. During pipe laying a permanent follow up of the local environmental conditions will be ensured in order to allow enough time to undertake contingency measures. Depending upon the weather forecast for the area, received from shore, and the actual site conditions, the lay barge Superintendent will decide to follow one of the two options described hereafter. COMPANY Site Representative onboard will be informed accordingly and consent sought about the proposed delay. 8.1.1

First Option

The bad weather is foreseen to increase quickly and to induce excessive loads in pipe, but it is anticipated to keep the barge on site: The pipe laying rate stays as its level until lay barge Superintendent decides to abandon the pipe according to personnel safety and pipe integrity. In this option, the A&R head will be welded to the pipeline and connected to the A&R cable and pipe will be abandoned. Please refer to Abandonment and Recovery procedure section 6.4. Once the abandonment/recovery head reaches the seabed, the abandonment and recovery cable is slacked and, if possible, the barge heading is turned into the swell/wind. Even if it was anticipated to keep the lay barge on site, the weather can deteriorate such that the lay barge has to sail away. In such case the A&R cable will be disconnected by divers and recovered, if diver‟s operation is not possible then cable is abandoned on the seabed with a pennant buoy on its extremity for later recovery. 8.1.2

Second Option

The bad weather does not endanger the barge or pipe lay safety but prohibits the unloading of pipes carrier vessel and is foreseen to stay as it is or to decrease slowly: The principle of this option is to try not to abandon the pipe; the steps will be as follows; i) The anchor handling tugs pick up the forward anchors and drops them at the maximum possible length. They then shorten the stern anchor lines. At the end of anchoring operations, the anchor pattern must be such as to allow the longest advance of the barge without new anchoring operations.

ii) The pipelaying rate is reduced according to pipe stock onboard the lay Barge and as per the slow laying rate procedure described in section below and in line with fatigue analysis report. It should be noted that pipelaying will continue as long as the tugs can move anchors. If this is not achievable, the pipe abandonment will be initiated on barge by Superintendent Initiative when the anchor pattern approaches the configuration which allows the minimum forward movement necessary to accomplish abandonment. A slow pipelaying rate will be adopted if the line pipe supply is critical or impossible for any reason, such as: 

Coming alongside the lay Barge is difficult, for pipe carriers or tugs, due to bad weather, residual swell, breakdown of tug, etc.



Impossibility for the tugs to pick up and handle anchors.



Breakdown of the unloading cranes.

The lower limit for such a slow rate is determined by the maximum time during which it is possible to keep the barge at a certain position without risking: 

Fatigue damage of the pipe due to stress fluctuations resulting from barge and pipe motions.



Damage to the coating due to distributed load over barge and/or stern rollers.

The fatigue damage of steel pipe during pipelay is usually unexpected even in the worst weather conditions. The only problem that may be encountered is damage to the anode or coating surface from repeated impact loads resulting from the pipe contacts with rollers. 8.2

Buckle Detection - General

A buckle is deemed to occur when the circular cross sectional profile of the pipe is distorted beyond allowable deformation stipulated in the installation code. This procedure deals specifically with wet and dry buckles. A dry buckle is deemed to occur when the inner pipe circular profile is distorted but the pipe-wall is not punctured; hence the pipe interior remains dry (not flooded). Dry buckles in the pipe during pipe lay may be detected by: 

damage of buckle detector gauge plates



Increasing of load cell during pulling buckle detector

A wet buckle is deemed to occur when the inner pipe circular profile is distorted and the pipe-wall is punctured; hence the pipe interior becomes wet (flooded). Wet buckles in the pipe during pipe lay may be detected as follows: 

visual observation on the barge ramps



tension/roller load monitoring



excessive excursion of the lay barge observed by dive survey

8.2.1

Visual Observation on the Pipe Ramps

In most cases the most stressed section of the pipe string during pipe lay is just beyond the stinger tip in the “over bend” region. CCTV cameras are mounted on the ramp, below the water line. A buckle occurring on the over bend region could potentially be seen on the CCTV monitors. 8.2.2

Tension/Roller load monitoring

There will be 24 hours monitoring and recording of rollers boxes load cells in order to ensure that the operation is within the acceptable bandwidth. 8.3

Buckle Repair - General

If a buckle is detected during pipe lay operations, the barge will immediately stop. Production along the firing line will also stop. Any anchors that were being re-positioned will, if necessary, be re-placed at their original location prior to the detection of the buckle. Once the extent of the buckle is determined, there are two basic approaches to buckle removal.

 Recovery of the pipeline – only after determining, via a diver survey, that it is safe to do so. Back up on the pipe, and cut the pipe joint by joint until the buckle is removed. A consideration when making this decision is the extent to which the pipe is permanently bent and consequently problems moving through the tension machine could occur.  Lay the pipe down, go back to the buckle point and cut the pipe, which will involve flooding and drying steps, this option is usually weather driven. It is more desirable to recover the pipeline through the tensioner and reinstate the pipe on the lay barge. The second option is to abandon the pipeline by laying down on the seabed and performing subsea remedial work. Every effort will be made to recover the pipeline, and the decision to lay the pipeline down will only be made if absolutely necessary. 8.4

Dry Buckle Recovery Procedure

Prior to proceeding with buckle repair operations, the internal pipeline line-up clamp and other internal equipments will be removed from the pipeline, and the firing line cleared of all none essential personnel. The lay barge will be backed up in steps of one joint. The pipe will be reversed out of the firing line and subsequently inspected prior to re-bevelling. Note: Joints, which cannot be re-beveled, will be quarantined for return to load out base. The lay barge will continue to back up until the buckled section is in front of Tensioner. The A&R head will be welded to the pipeline and the A&R cable will be attached to the head. Tension will be transferred from the tensioner to the A&R winch. The tensioner will then be opened. The barge will afterward be backed up until the buckled section has cleared the tensioner. Tensioner will then be closed and tension transferred from the A & R winch back to the tensioner. The A&R head and remaining joints will be cut out until the buckle has been removed and the first acceptable field joint is reached. Note: If the buckle is sufficiently minor, the Lay Barge Superintendent may choose not to weld on the A&R head, and to recover the buckled sections through the tensioner in turn The pipeline end will then be re-bevelled and the internal pipeline equipment replaced in the pipe. Normal pipe lay operations will resume. Pipelay records and as-laid length will be amended to reflect the line pipe joints cut out. Pipe joints cut out will be inspected and quarantined if necessary. Cut out joints that are undamaged will be re-bevelled and enter the production system again. 8.5

Wet Buckle Recovery Procedure

The occurrence of a wet buckle will be immediately detected, as the load of the rollers will increase significantly. If due to the heavy weight, the flooded pipeline cannot be recovered through the tensioner then the following procedure will be followed: i)

The pipeline will then be fitted with the A&R head and abandoned on the seabed.

ii)

Diver will be used to ascertain the extent of the damage to the pipeline.

The vessel will then position above the damaged pipe section and the pipeline will be cut at a location determined by the lay barge superintendent. The damaged pipeline section will be moved clear of the area and recovered with wet buckle recovery head. The relevant Pipeline recovery tool will be inserted into the intact end of the pipeline, and the lay barge A&R wire will be attached to the recovery tool. Since the pipeline cannot be recovered in the flooded condition the pipeline will be dewatered via the contingency pig in the pull-in head or A&R head from the shore approach location prior to commencing recovery. The water present in the pipeline will bypass the Pipeline recovery tool.

The barge will then back-up and recover the pipe string onto the barge through the tensioners as detailed in the Jascon 2 abandonment and recovery procedure. The joints in the vicinity of the wet buckle will be inspected thoroughly for damage. If damage has occurred to a joint the barge shall be further backed up and the damaged pipe removed. The pipeline end will then be re-bevelled and the internal pipeline equipment replaced in the pipe. Normal pipeline operations will recommence. 8.6

Stinger Failure

Probable cause of damage is one of the following: 

roller box failure



load cell failure

Following remedial action shall be adopted: 

Divers will inspect to ascertain the location of damage in stinger.



If stinger can be fixed without pipeline abandonment, divers will repair it with crane assistance.



If damage is serious, the pipeline will be abandoned and damaged parts will be removed and replaced by divers/mechanics.

8.7

Tensioner Failure

This can be caused by one of the following: 

Mechanical parts Failure



Electronic parts Failure

For safety reasons the following remedial action shall be adopted immediately: 

Using the A&R winch to lay down the pipe.



Damaged tensioner would be repaired afterward.

If repairs to the tensioner cannot be completed within a short period (less than two hrs.), the internal line-up clamp shall be removed from the pipeline. The abandonment head shall be welded to the pipeline. Tension on the A&R cable shall be transferred to the pipeline-securing sling aft of the tensioner. Release the A&R cable from the forward choker and shackle A&R cable to abandonment head. Increase tension on A&R cable to transfer complete operating tension from tensioner to A&R winch. Maintain constant tension on the pipeline. 8.8


Normal laying operation requires minimum of two different AHT to assist Jascon 2 during anchor running. If breakdown of one support Tug occurs, it will be replaced by another. In case that no substitutive tug is available for assistance [due to simultaneous operations on field] pipelay may temporary continue under reduced production rate. This will guaranty enough time to safely redeploy anchors by means of only one AHT.

9

WORK PLAN

The Work Plan is made up of various sections of activities to be undertaken during the Pipe lay operations. Please see various sections for the respective work plan. Work Plan 001: Pre-Mobilization S/N

Description of Steps

References

1.

Issue all relevant documentation to all parties involved

2.

Issue Notice to Mariners.

3.

Check A&R winch status pennant wire on J2 deck.

4.

Check Tensioner Brakes.

5.

Check tension transfer between tensioner and winch.

6.

Check opening of tensioner.

7.

Responsible Person

MDR

Project Manager

NA

Lay Barge Master

NA


SAS equipment manual


NA


SAS equipment manual


Check load cell of the A&R winch.

NA


8.

Check status of internal line up clamp.

NA


9.

Check roller box load cells and cameras and lights.

NA


10.

Check Pipe Joints


11.

Check Lay down head.


12.

Four (4) Pipe joints and initiation head welded as string in firing line.

13.

Check Slings/Shackles/Clips,


14.

Check DMA and pennant buoy


with

NA

Check


NA 15.

NDT, Equipment, Welding, Consumables, grinder, Gases, Discs, etc.

Offshore Field Engineer Materials Coordinator

/

Work Plan 002: Mobilization After the pre-mobilization activities, Jascon 2 shall be mobilised for the offshore pipe lay. Other step by step activities that will be undertaken as part of mobilisation for the pipe lay campaign include but are not limited to the following. Steps


References

1

Obtain weather forecast for the pipe lay location area

NA

2

Ensure Survey equipment on board is fully operational and calibrated.

NA

3

Arrange harbor pilot and towing tug as required for safe departure

NA

4

Obtain Command and Control Mobilization approval from Company‟s Offshore Construction Group.

NA

5

Depart from mobilization port and sail to pipe lay location.

NA

6

NDT Equipments and consumables , Welding Equipments and Consumables, Diving Equipments, HSE Equipments etc.

NA

7

Rigging Equipments

NA

8

Splice first end of initiation wire (on winch drum) and connect to stem of DMA.

NA

Set-up at location; confirm position.

NA

9

Responsible Person Lay Barge Superintendent

Survey Party Chief Lay Barge Superintendent Lay Barge Superintendent

Lay Barge Superintendent Lay Barge Superintendent

Lay Barge Superintendent Lay Barge Superintendent

Survey Party Chief

Check

Work Plan 003: Initiation Operations The following tasks will be conducted under the instruction of the lay barge Superintendent who is fully responsible for all barge operations and determine if the weather conditions are suitable for pipeline initiation and subsequent commencement of pipe lay. The initiation operations will be undertaken with any of the five methods for applicable pipelines according to the individual requirement of the platform. The initiation tasks are described in the following work plan below.

Steps


References

Responsible Person

Check

Hanging Initiation Option 1.

Start welding of line pipe to pipe string already in the firing line.

Lay barge superintendent

2

Grip pipe with tensioner as soon as pipe passes tensioner.

NA


3

When pipe strings comes to the end of the last stinger roller, stop welding pipe and put on tensioner

NA


4

Position Jascon2 lay Barge with stern towards the Installation target location, heading 0 deg.


5

Connect Initiation Cable between the Attachment C Jacket leg and the pull head of the pipeline. Lower the Stinger.

Diving Supervisor / Lay barge Superintendent

DMA Initiation Option: See Attachment D 6

Position J2 with stern at DMA Installation target location, heading 0 deg for the applicable pipeline.


7

Connect upper loop of pennant wire to whip hoist using short sling.


8

Lift pennant system with DMA from deck, slew and lower to seabed, paying out sufficient initiation wire from winch.


9

Stop lowering as soon as hook load drops indicating DMA on seabed.


10

Release pennant wire from hook, using winch along boom.


11

Move J2 ahead slowly along target route paying out initiation wire from winch (monitor wire departure angle)



12

Hang off final part of initiation wire to deck using chain section.

References

Resp. Person


Check

13

Move J2 back to ensure that initiation wire hangs near vertical.


14

Disconnect end of initiation wire from winch.


15

Lift initiation wire end with whip hoist of main crane, slew over to stinger and lay initiation wire at the last stinger roller.


16

When pipe strings comes to the end of the last stinger roller, stop welding pipe and put on tensioner.


17

Secure the initiation wire by the last stinger roller with a chain section and disconnect the crane whip hoist.


18

Connect slack initiation wire to pad eye at start-up head by shackle and release chain.


19

Connect Initiation Cable between the Jacket and the pull head of the pipeline.

Diving Supervisor

20

Move the barge forward to take slack out of initiation wire.


Sheave Pulling Option 21


22


NA


23

When pipe strings comes to the end of the last stinger roller, stop welding pipe and put on tensioner

NA


24

Position J2 with stern towards the Platform Installation target location, heading 0 deg


25

Connect Initiation Cable between the Attachment D Jacket and the pull head of the pipeline.


Steps



References

Responsible Person

Bow-String Option 26



27


NA


28

When pipe strings comes to the end of the barge, stop welding pipe and put on tensioner

NA


29

Position J2 with stern towards the Platform Installation target location, heading 0 deg


30

Connect Initiation Cable between the Attachment E Jacket leg and the pull head of the pipeline.


Check

Survey crew will confirm actual location and orientation of the initiation head. Reference datum will be centre of pull pad eye on the initiation head.

Work Plan 004: Normal Lay Operations The normal lay activities shall begin thus, following the step by step approach below: Step

Action

Drawing/Document Reference

Responsible Party

1.

Once the initiation cable is connected pipelay operations can commence.

Offshore Field Engineer/Welder Foreman/ Lay Barge Master

2.

Pipe joints will be transferred from the pipe haul vessel to the pipelay vessel prior to start of pipelay. Pipe joints will be swabbed to ensure they are clean and pipe bevels shall be checked to ensure they are not damaged and re-beveled if damaged.


3.

Each joint will be transferred into the firing line and the butt end aligned with the previously installed joint. Alignment will be achieved by use of up-and-down rollers and side-to-side rollers.

Lay Barge Master/Dive Supervisor

4.

Once the correct alignment is achieved, the line-up clamp will be engaged.


5.

The root and hot passes weld will be made in the bead stall and welding, NDT and FJC will be done at the other work stations. NOTE: It will not be permitted to advance the pipe until the root and hot passes have been completed.


6.

When work is complete at each workstation, they will indicate so. A series of lights are switched on in the pipe alley that shows the personnel in the tower that the weld has been completed and the barge can begin pulling pipe.

NA

Lay Barge Master

7.

When all workstations have indicated that their work is complete, a signal will be given for those in the firing line to move away from the pipe.

N/A

Lay Barge Master

8.

The barge pulls ahead on anchors, one joint length as the tensioner pays out pipe under controlled constant tension.

NA

Lay Barge Master

9.

The joints will be welded up using the welding procedure as per the requirements of the appropriate WPS.

Pipeline and Riser


10.

Upon completion of each weld, the weld area will be buffed with a wire wheel to prepare for the NDT.

QA/QC

11.

Each weld will be examined using radiograph system in NDT Station on the firing line. Each radiograph film will be reviewed by certified Radiography inspectors for unacceptable defects.

QA/QC

12

Upon acceptance of the weld by radiograph, the field joint area will be covered with suitable anti corrosion coating.

QA/QC

Work Plan 005: Laydown Operations Step

Action

Drawing/Document Reference

Responsible Party

1.

Survey will inform the Barge Superintendent that the final joint should be loaded into the firing line. At this time normal lay operations will be suspended.

N/A

Lay Barge Master

2.

The laydown joint will be moved into the line-up station. An internal equipment to be taken out, and then weld laydown head on the end of the final joint. It may be necessary to cut the final joint in order to laydown the pipeline in the proper location.

N/A

Lay Barge Superintendent/Lay Barge Master/Offshore Field Engineer

3.

The final joint will be welded using normal welding procedures and will be coated the same as the previous joints

Superintendent/Welding Foreman

4.

Once the weld, NDT, and coating are complete the A / R wire will be connected to the laydown head. The firing line will be cleared of nonessential personnel prior to the connection of the A/R cable

Lay Barge Master

5.

Close all valves on the laydown head (if applicable)


6.

The A / R winch will slowly take the load of the pipeline

Offshore Field Engineer/Lay Barge Master

7.

Once the A / R winch has the load of the pipeline the tensioner will be opened up and the total load will be on the A / R winch.


8.

The barge will slowly move ahead as cable is paid out. The pipe will be monitored (A & R load indicator) by Tower Operators to ensure proper tension is maintained throughout the laydown.

Offshore Field Engineer /

9.

The barge will slowly move ahead and pay out cable until the pipeline is on bottom.

Offshore Field Engineer /Lay Barge Master

10.

Once the pipeline is on bottom the barge will back up while retrieving cable


11.

When the stern of the barge is over the pipeline the A/R wire will be removed from the stinger using a snatch block on the auxiliary block

Dive Supervisor

Lay Barge Master

and brought to the stern of the barge 12

Diver to establish crossover line to the laydown head

Dive Supervisor

13.

Diver to establish downline at the laydown head.

Dive Supervisor

14.

Diver will disconnect the A/R cable from the laydown head and the topside crew will recover remaining cable.

Dive Supervisor/Lay barge master

15.

It may be necessary to remove the downlines from the pipeline if the barge is to leave location. Diver to return to the barge.

Dive Supervisor

Pipelay Procedure Revised

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