Introduction to Subsea pipe lines

8/10/2019 Introduction to Subsea pipe lines

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Presented by :

Ashok Kumar -01

Gaurav Kumar-02

Harshul Nimje-03

1Indian Maritime University - Visakhapatnam Campus


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INTRODUCTION A submarine pipeline (also known

as marine, subsea or offshore pipeline) is a pipeline that is

laid on the seabed or below it inside a trench.

Submarine pipelines are used primarily to carry oil or gas, but

transportation of water is also important.

A distinction is sometimes made between a flowline and a

pipeline. The former is an intrafield pipeline, in the sense that

it is used to connect subsea wellheads, manifolds andthe platform within a particular development field.

The latter, sometimes referred to as an export pipeline, is

used to bring the resource to shore.



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Flowlines Pipelines

Flowlines transport unprocessed

fluid crude oil or gas.

The conveyed fluid can be a multi-

phase fluid possibly with paraffin,

asphaltene, and other solids like

sand, etc.

The flowline is sometimes called a

production line or import line.

Most deepwater flowlines carry veryhigh pressure and high temperature

(HP/HT) fluid.

Pipelines transport processed oil or gas.

The conveyed fluid is a single phase fluid

after separation from oil, gas, water, and

other solids.

The pipeline is also called an export

line.

The pipeline has moderately low

(ambient) temperature and low pressure

just enough to export the fluid to the

destination.

Generally, the size of the pipeline is

greater than the flowline


NOTE :It is important to distinguish between flowlines and pipelines since the required

design code is different


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SUBSEA PIPELINE SYSTEM



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PIPE LINE CHARECTREISTCS Submarine pipelines generally vary in diameter from 3

inches (76 mm) to 72 inches (1,800 mm) for high

capacity lines. Wall thicknesses typically range from 10millimetres (0.39 in) to 75 millimetres (3.0 in).

The pipe has to be designed for fluids at hightemperature and pressure. The walls are made fromhigh-yield strength steel, 350-500 MPa (50,000-70,000 psi), weld ability being one of the mainselection criteria.



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Sequence of flow

7

Well headplatform

Process +living quarters

Tankeroffloading

Sub seapipeline

Onshore gasterminal

Indian Maritime University - Visakhapatnam Campus


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Modes of hydrocarbon (INDIA)



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FACTORS SEABED.

SOIL CONDITION

SEA MOBILITY

SUBMARINE LANDSLIDES

CURRENTS

WAVES

ICE RELATED ISSUES

PIPE ROUTING



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What can be Transported ? Liquids

Crude Oil

Petroleum Products

Petrochemical Products Chemicals Solids(in slurry

form)

Water

LPG

Gases Natural Gas

Any other Gas

Petrochemical Products Chemicals Solids(in slurry

form)

Coal

Ores

Tailings



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DifferenceOnshore pipelines Submarine pipelines

Cross Country Pipelines

Spur Lines Gathering & Distribution

lines

Trunk lines

Infield pipelines Intra field

Offshore terminals

Effluent outfalls



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Why pipelines? Environment friendly

Least energy requirement

Lowest maintenance costs

Minimal impact on land use pattern

Negligible loss of product in transit

High reliability



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Stages of a Project Conceptual Study

Feasibility Study

Basic Engineering

Detailed Engineering

Construction

Testing & Commissioning



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Conceptual Study Establish System Requirement

Evaluate Constraints on System Design

Identify Interface With Other Systems

Develop Design Data Requirements

Assess Construction Methodology

Finalize the Concept



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Feasibility Study Evaluate Technical Options

Eliminate Unviable Options

Firming up of Process Facilities

Develop Broad System Specifications

Establish Project Cost

Plan Project Implementation Scheme



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Basic Engineering

Finalize Process Scheme & Equipments

Environmental & Process Data Review

Pipeline Routing & Size Optimization

Establish Requirements for

Surveys and Investigations

Material of Construction

Preliminary Analysis

Construction, Testing and Commissioning

Develop Implementation Schedule



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Safety Aspects Environmental Parameter and Soil Data

Pipeline Stability

Shore Approaches

Trenching and Burial

Safety of Existing Facilities



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Detailed Design & Engineering Engineering Design basis

Route Engineering & Surveys

Engineering analysis and Calculations

Specification and Job Standards

Engineering for Procurement

Drawings for Construction

Installation analysis and Procedures



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Construction, Testing &

Commissioning

Pipe Corrosion Concrete& Coating

Welding and Joint Coating Pipeline Laying

Specialty Items Installation

Riser Installation

Pipeline Crossing Installation

Testing, Dewatering, Drying and Commissioning



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Surveys The marine survey includes all operations required toobtain the bathymetry, morphology of the sea bottom

and shallow geology

Geo-physical & Geo-technical Surveys Platform Approach / Riser Face Survey

20Indian Maritime University - Visakhapatnam CampusFig : observations


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Route Selection The shortest distance between end points may result in

minimum material costs,

But may not necessarily be the optimum pipeline route

Routing Considerations

Low cost (select the most direct and shortest P/L route)

Seabed topography (faults, outcrops, slopes, etc.)

Obstructions, debris, existing pipelines or structures

Environmentally sensitive areas (beach, oyster field, etc.)

Marine activity in the area such as fishing or shipping Installability (1st end initiation and 2nd end termination)

Required pipeline route curvature radius

Tie-in methods



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Route Optimization

For seabed with onerous terrain significant savings on construction

and installation costs may be achieved by route optimisation

Need accurate cost data for: Supply of pipeline

Fabrication cost

Free span correction

Trenching, rock dump, weightcoat, anchoring

Pipeline design must be reasonably complete before route

optimisation can be done



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Pipeline Wall Thickness Selection

Analysis / Calculations

Hoop Stress

Buckle Initiation Buckle Propagation

Collapse Bucking

Local Buckling

Pipeline Stress Checks Hoop Stress

Equivalent Stress



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Anti Corrosion Coatings Coating Anti-Types

Coal Tar Enamel

Fusion Bonded Epoxy

Selection Criteria Service Conditions

Performance Record

Ease of Repair

Cost Effectiveness Compatibility with Concrete

Coating

25Indian Maritime University - Visakhapatnam CampusFig : CTE

Fig : FBE


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Pipe Coatings1. Corrosion Coating

Inner surface protection-

fusion bonded epoxy (FBE)

coating or plastic liner is

applied. Outer surface- carbon steel-

FBE or neoprene

Abrasion resistant overlay

(ARO) is commonly applied

for the horizontal directional

drilling (HDD) pipes or bottom

towed pipes.


Fig : 3LPE Coating

(high density polyethylene )


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Pipe Coatings2. Insulation Coating

To keep the conveyed fluid

warm , heated by active or

passive

Active- electric heat tracingwires wrapped around the

pipeline, circulating hot

water through the annulus of

pipe-in-pipe, etc.

passive heating method is

insulation coating, burial,

covering, etc.


Fig: GSPU (Glass syntactic polyurethane)

Fig : Syntactic Foam Insulation


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Pipe Coatings3. Pipe-in-Pipe

an inner pipe is covered by

a larger outer pipe

The annuls between inner

pipe and outer pipe arefilled with insulation

materials

Eg- micro-porous silica

(Aerogel), polyurethane

foam(PUF),

Wacker/Porextherm,

Mineral wool, etc.


Fig : PIP


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Pipeline Coating4. Concrete Weight Coating

applied to make the pipestable under the water

Concrete coating is the

most cost effective optionto increase pipe weight.

The polyethylene outerwrap in the picture isremoved after the concrete

coating is cured left without concrete

coating for welding andwelding inspection


Fig :Concrete Weight Coating

Fig:Coating Cut-Back Length


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Field Joint Coating After the field weld is made, each pipe joint should be coated with a

corrosion resistant coating. The field joint coating (FJC) can be done by FBE, heat shrink sleeve, or

PU foam (for concrete coated pipe).


Fig : Field Joint

Coating


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CATHODIC PROTECTION DESIGN Corrosion is a deterioration of a material

Corrosion resistance coating is applied to prevent

corrosion Cathodic protection (CP) system using anodes is used as

a supplemental corrosion protection system.

Corrosion coating can be damaged during pipe

transportation and installation.

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Fig :CP System ComponentsIndian Maritime University - Visakhapatnam Campus


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CP system Half shell anodes are

tied-on the pipe outer

surface at certain

intervals. Typically 75 to 115 lb

aluminum alloy anodes

are installed at 200 to

1,000 ft intervals. Design guidelines can be

found at DNV-RP-F103

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Fig:Anode Types for Pipeline CP System



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Pipeline inspection Pressure tests

External pipeline inspection (Direct Assessment)

Internal pipeline inspection (in-line inspection)


Fig : Pressure testing (left)& Internal inspection(right )


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Internal &External inspection

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Fig :The bristle-actuated pipelinetractor is powered through riser and

operated by brush modules that when

actuated against each other provide a

high pull-capability along the riser or

pipeline (left)

Fig :Guided ultrasonic waves are used toscreen long length of pipeline (several

tens of meters) for corrosion or cracks

from a single transducer location.)



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Requirements Regarding Pipeline

MaintenanceThe maintenance process must ensure that:

The pipeline is always operated safely

The pipeline is operated efficiently and economically

The pipeline is compliant

The pipeline is available.

A typical inspection and monitoring system includes:

Polymer monitoring: online, offline, topside and subsea; Annulus monitoring: vent gas rate, annulus integrity;

Riser dynamics: tension, angle and curvature;

Steel armor: inspection method, magnetic or radiographic;

Use of existing sensors, pressure and temperature sensors.



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References[1] Http://En.Wikipedia.Org/Wiki/Submarine_pipeline

[2] Introduction To Offshore Pipelines And Risers/JaeyoungLee, P.E. /2008

[3] Offshore Pipeline Systems/Raj Kumar/Sr. Manager/EIL

[4] Ocean Engineering Series Volume 3 - Pipelines AndRisers/Series Editors/R. Bhattacharyya & M.E. Mccormick

[5] Handbook Ofoffshore Engineering Subrata K. ChakrabartiVOV1&2/Subrata K. Chakrabarti



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Introduction to Subsea pipe lines

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