pipeline research council international, inc

Pipeline Research Council International, Inc.

Kick-off Meeting

EC-8-8:

Guidelines on the Selection and Application

of Cathodic Protection Coupons:Phase 2: Model Refinement through Laboratory Testing

Bi Wuxi

Oct 24th 2018

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Outline

Project Overview Coupon Polarization Testing in Field Review（ Phase 1） Laboratory Testing Plan for Phase 2

- Coupon Edge Effects Testing - Coupon Base Plate Lateral Width Effects Testing- Coupon Coating Under-Cut Effects Testing- Coupon Polarization Characteristics Under Different Orientations / Distance to the

Pipe- Pipeline Backfill Soil Effects Testing- Coupon Testing under AC/DC Stray Current Conditions

Key Points for Phase 2 Schedule for Phase 2

Project Name: Guidelines on the Selection and Application of Cathodic Protection Coupons: Phase 2 (EC-8-8)Research Objective Alignment: #4 Improve the accuracy and application of

fitness for service methodologies by reducing uncertainties.

Team Leader FONTAINE Sylvain, GRTgaz Project Completion Estimation 2019

TC Research Area Leader David McQuilling, PG&E TRL Stage at start of 2017 and TRL State at end-2017 TRL 7 -TRL 7

Member Beneficiaries Liquid & Gas Operators & Associates Pilot/Field trial needed? If yes, where & target date

Yes, by end of 2018, China and US locations

Project Overview Brief description of technology: CP coupons are used extensively in the

industry to assess CP levels, yet there are no accepted guidelines for determining the most appropriate coupon configuration and application. The objective of this project is to develop guidelines which will fill this need.

Goal/Deliverables: Give guidelines and recommendations describing how a coupon is representative of the CP level of a pipeline. Establish the technical knowledge for CP coupon selection and application.

Challenges Risks & Mitigations:

Risks: Challenges are (1) how to obtain coupon cathodic polarization curves for typical soils and depths, (2) how to select and determine the controlling soil parameters which dominate coupon polarization behavior.

Mitigations: Besides in-depth related literature reviewing, soil and electrochemical experts will be invited to join in and give professional suggestions on how to perform polarization curves testing and how to select controlling soil parameters.

Strategic Driver Alignment: Aligns directly with the corrosion area research objectives and roadmap. This project improves CP testing accuracy and reliability.

Cylinder shape coupon edge effect

Insert picture here

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Project Overview

Project Value Proposition: Guidelines and recommendation describing how a coupon of representative of the CP level of a pipeline, guidelines for CP coupon selection and application, significance of each coupon design parameters, how to design best coupon for average coating holiday.

Primary Benefit of this work is: Study the unclear CP coupon related problems and provide accepted guidelines for coupon selection and field application.

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Outline


- Coupon Edge Effects Testing - Coupon Base Plate Lateral Width Effects Testing- Coupon Coating Under-Cut Effects Testing- Coupon Polarization Characteristics Under Different Orientations / Distance to the



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Field Polarization Curve Testing

Coupon Polarization Testing in Field Review（ Phase 1）

In Phase1, a large scale of coupon polarization curve testing are performed to obtain reliable boundary condition for coupon numerical modeling.

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-6 typical soils are covered:

Coastal Saline Soil (2.3 Ωm)

Inland Saline Soil (4.5Ωm)

Meadow Soil (rich of organic matters, typical for farming; 46.2 Ωm) , and

Dry Sandy Soil (560.7 Ωm)

Medium Moisture Sandy Soil (22.0 Ωm)

Yellow Clay Soil (803.5 Ωm)

-2 coupon sizes: 5cm2, 50cm2

-2 coupon coatings: FBE (1.00mm) and 3LPE (3.00mm)

- Coupon depth effects: Assessed by 5 parallel coupons from 0.3m to 2.0m.

-Coupon aging effects: 4 test sites are seleceted to do coupon aging tests.

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Field Polarization Curve Testing

Shenyang

Daqing

Yingtan

DaGangKorla

Golmud


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Main Conclusions of Coupon Polarization in Field are:• Generally, coupons exhibit a scattered polarization behaviors in soils, and there is no

obvious common law of how polarization curves change with soils and depths except: The coupon IR-drop in low resistivity soil (like saline), is always very small, and larger

current density is needed to get coupons protected. Coupons, buried in sandy soil, tend to share the same polarization behavior, regardless of

depths.

• Aging effects tend to force coupon polarization curves getting close.• Water level has great influence to coupon polarization behavior.• The influence of coupon coating to polarization curves is not supported by field test

data. • An universal law is found, 50ms-delay phenonmenon. Coupons always take about

50ms to finish the instant-disconnection action.


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Coupon Numerical Modelling are Divided into 4 Points: Coupon Edge Effects Study

-3 typical soil conditions: Inland Saline Soil (4.5Ωm), Meadow Soil (rich of organic matters, typical for farming; 46.2 Ωm) , andDry Sandy Soil (560.7 Ωm)

-3 coupon sizes: 5cm2, 30cm2, 50cm2

-4 coupon shapes: circular, rectangular, cylinder and ring. -Coupon coatings: Flush (no coating), FBE (1.00mm) and 3LPE (3.00mm) 4 typical coupon geometry ratios (GR)

- Coupon Orientations and Distance to the Pipe 4 coupon orientations: face to the sky, back to the pipe, face to the pipe and face to the Earth core. 3 typical soil conditions: Inland Saline , Meadow Soil and Dry Sandy Soil Separation: from 1D to 20D (D: diameter of Coupon)

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Coupon Numerical Modelling are Divided into 4 Points: Coupon Base Plate Lateral Width Effects

-Base Plate lateral Width: from 0 to 5D (D: diameter of Coupon)

-3 typical soil conditions: Inland Saline , Meadow Soil and Dry Sandy Soil

-3 coupon sizes: 5cm2, 30cm2, 50cm2

- Coupon Coating Under-cut Effects

- Disbonded space length: 1cm, 2cm and 3cm

-Disbonded height: 0.3cm, 0.4cm and 0.5cm

3 typical soil conditions: Inland Saline , Meadow Soil and Dry Sandy Soil

3 coupon sizes: 5cm2, 30cm2, 50cm2

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Main Conclusions of Coupon Numerical Modeling are:• Coupon shape and edge effects are negligible for low and medium (<100Ωm)

resistivity soils.• Coupon shape and edge effects become obvous when buried in high resistivity soils,

and increase with coupon size. • Coupon coating especially 3LPE plays a key role in decreasing the coupon edge

effects in high resistivity soils. • Coupon shielding is hard to happen. Coupon shielding start to work only when in

high resistivity soils, facing to the pipe and the coupon within 2D region to the pipe. • Coupons with very thin base plate lateral width, always tend to get more CP current

than the same size and shape holidays on a real pipe. A ≥ 3D coupon base plate lateral width is recommened for all coupon application.

• Both CP current and CP potential decrease sharply under coating disbonded part.


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Outline


- Coupon Edge Effects Testing - Coupon Base Plate Lateral Width Effects Testing - Coupon Coating Under-Cut Effects Testing- Coupon Polarization Characteristics Under Different Orientations / Distance to the Pipe- Pipeline Backfill Soil Effects Testing- Coupon Testing under AC/DC Stray Current Conditions


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Purpose of Phase2

Refining numerical models used in Phase1 and verifying the conclusions from

numerical modeling by parallel lab tests.

Overview of Phase2Six lab tests are proposed in this Phase.TEST1: Coupon Edge Effects Test TEST2: Coupon Base Plate Lateral Width Effects TestTEST3: Coupon Coating Under-cut Effects TestTEST4: Coupon Polarization Characteristics Under Different Orientations /

Distance to the PipeTEST5: Pipeline Backfill Soil Effects TestTEST6: Coupon Testing under AC/DC Stray Current Conditions

Laboratory Testing Plan for Phase 2

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TEST1: Coupon Edge Effects Testing

4 typical coupon shapes

TEST1 will be performed in electrolyte

solution by potential scanning on coupons

with different sizes and shapes.

• 4 coupon shapes: circular; rectangular ;

ring and cylinder

• 3 coupon sizes: 5cm2, 30 cm2 and 50 cm2

• Coupon coatings: Flush, FBE and 3LPE

• Current density: 1A/m2; 5A/m2and 10A/m2.

• Resistivity of electrolyte:～5 Ω•m,～

50Ω•m,～550Ω•m


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Micro-region potential scanner

• Potential scanning set :

A micro-region potential scanner will

be used to do the test with a step

motor, lead rail, screw rod, and SCE

reference.

• SCE reference will be installed with a

0.2mm capillary.

• “U” Glass container: One side for

coupon and the other for anode, a

porous membrane will be set up to

shield anode interference.Capillary with 0.2mm lead


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Scanning Path of RE

• Scanning speed : to restrain disturbance to

polarization, scanning speed will be Less than 1mm/s.

• Sampling rate : 5S/s, and may be adjusted according to

the result.

• Scanning Path: cover the whole coupon surface.

• Data post-processing: present the polarized potential

color map with MATLAB or Origin software. Objectives: To find out the level of coupon edge effects in different

resistivity electrolyte on coupons with different shapes and sizes.

Verifying the results given in Phase1.

Potential distribution


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TEST2: Coupon Base Plate Lateral Width Effects TestingCircular coupons will be used to perform this test in electrolyte solution. Following the idea of Russian Doll, the coupon base plate lateral width will increase from 0 to 4D while recording the coupon current and polarized potential. Repeat this procedures for different coupon sizes and electrolytes. • Coupon shape:

circular only• Coupon sizes:

5cm2, 30 cm2, 50 cm2

• Plate lateral width: from 0 to 4D.

• Electrolyte resistivity: ～5 Ω•m, ～50Ω•m,～550Ω•m


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TEST2: Coupon Base Plate Lateral Width Effects Testing

• Coupon constant potential to remote earth boundary condition (a little more positive than -1.2Vcse) will be used in this test by classical three-electrode system.

• Data Collection: polarized potential, current, and then spread resistance of the tested coupon.

• “U” Glass container will be the same as TEST1.

Objective: To find out how coupon base plate lateral width influences coupon current, polarized potential and spread resistance.


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TEST3: Coupon Coating Under-Cut Effects TestingWire Beam Electrode (WBE) will be used to do this test. to perform this testing.The idea of WBE technology is to divide the coupon surface into many small local areas (active point matrix), and the local current and potential can be recorded by a special scanner. • Coupon shape: circular. • Exposed area of WBE: 5cm2, 30 cm2, 50 cm2

• Electrolyte resistivity: ～5 Ω•m, ～50Ω•m, ～550Ω•m

WBE

A special scanner for WBE


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TEST3: Coupon Coating Under-Cut Effects Testing• Coating Under-Cut simulation :

We will design a series of PVC molds for install WBE to simulate different disbonding area with different heights and lengths.

• The height of disbonding: 1～5mm;• The length of disbonding: 10～30mm;• The tests arrangment is shown in

following table

Coating Under-Cut on WBE

Type Size(cm2) Height of disbond(mm)

Length of disbond(mm)

Flush

5 1 10

30 3 20

50 5 30


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TEST4: Coupon Polarization Characteristics Under Different Orientations / Distance to the Pipe

A large electrolyte solution glass tank(L×W×H: 3m×2m×1m) will be used to

install a coated pipe (L: 2m, D:219mm) and test coupons. The polarization

difference between the real holiday in the pipe coating and test coupons will

be studied.

A diagrammatic sketch of testing

• Coupon sizes:5cm2, 30 cm2, 50 cm2

• Electrolyte resistivity:～5 Ω•m,～50Ω•m,～550Ω•m

• Current density: 1A/m2, 5A/m2, and 10A/m2


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• Coupon shapes: circular; rectangular; ring and cylinder

• Real holiday sizes and positions on the pipe : 5cm2, 30 cm2, 50 cm2 holidays will be set at 12:00, 3:00 and 6:00 of the pipe.

• 4 shape holidays at each position on the pipe: for each position (12:00, 3:00 and 6:00), same-size holidays with different shapes (circular, square, rectangle and strip) will be prepared along the axial direction of the pipe. So there will be 12 real holidays on the pipe.

For each testing, only one coupon and one holiday keep active for testing, and other holidays will be sealed.

3 sizes holiday on pipe

4 shapes holiday on the pipe


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• Coupon orientations: Face to pipe, Back to pipe, Face to sky and Face to the Earth core.

• Distance between the coupon and pipe: The distance will be changed from 1D( diameter of coupon）to 100cm.

Orientation of coupon


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Items Holiday Group1 Holiday Group2 Holiday Group3 Holiday Group4

Holidays on the pipe

Shapes Circular square Rectangular strip

Area (cm2) 5, 30, 50 5 (GRs[1]=1) 30(GRs=3) 50(GRs=5)

Positions 12:00, 3:00, 6:00

Test coupons

Shapes: Circular, Rectangular, Cylinder, and Ring

Area (cm2) 5, 30, 50

GRs Four typical GRs (except circular coupons)

Orientations Face to pipe, Back to pipe, Face to sky and Face to the Earth core.

Distance to the pipe 1D～100cm[2]

Current density 1A/m2, 5A/m2,and 10A/m2

Interrupter① Disconnect coupon from pipe only

①,② Shut off CP current supply and disconnect coupon from pipe simultaneously

[1] GR=Length/Width of holiday. [2] D = The diameter of the coupon.


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Date collection for each size of coupon and holiday:Two interrupters and one ZRA (zero resistance ammeter) will be used in this test. Function of each instrument: Interrupter ①: disconnect coupon from the pipe and obtain the polarized potential. ZRA: record coupon current. Interrupter ① and interrupter ② simultaneously: obtain coupon and holiday polarized

potential at the same time.

We can obtain polarized potential for the test coupon and real holiday on the pipe.


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TEST5: Pipeline Backfill Effects TestThe purpose of this test to verify how backfill soil influences the couponpolarization behaviors.This test will be performed in a real soil tank. The tank will be separated intotwo parts by a plastic plate. Backfill soil and original soil will be filled at eachside of the plastic plate. Finally pull out the plate to make a man-madeenvironment for backfill soil test. Bury two coupons with the same size, shapeand surface condition in two soil conditions separately by drilling.


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TEST5: Pipeline Backfill Effects Test

Coupon and holiday sizes: 5cm2, 30 cm2, 50 cm2. Shape of coupon and holiday: Circular onlyCurrent density: 1A/m2, 5A/m2, and 10A/m2

Data collection: Scanning the holiday and two coupons’ polarization curves twice with the instant-off method as used in Phase1, after one-day aging and one-week aging respectively.


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TEST 6: Coupons Tests under AC/DC Interference Conditions

Two purposes to do the this test: − How to measure the coupon polarized potential under AC stray current

condition (Does coupon instant-off method still work with AC depolarizer?).− How to minimize the IR-drop under DC stray current condition.

For purpose1: Base on the test set of TEST1, a AC stray current condition will be prepared with interfered pipe (with CP) and bonded coupon.We will use to different ways to obtain coupon polarized potential, one with instant-off method, the other with spread resistance method. We will compare the polarized potential difference from the two ways:


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TEST6: Coupons Tests under AC/DC Interference Conditions

3 sizes of coupon and holiday : 5cm2, 30 cm2, 50 cm2

AC current source: An AC signal source will be used to generate sinusoidal AC voltage, and the current density on coupon will be set at 30A/m2, 60A/m2, 100A/m2

Resistivity of electrolyte solution :～5 Ω•m,～50Ω•m,～550Ω•mDC current density: 1A/m2, 5A/m2, and 10A/m2

Reference electrode: SCE at remote earth


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For propose 2:Finding out which way is the most effective way to eliminate IR-drop is the objective of this test.Commonly used eliminating coupon IR-drop method includes soil tubes, IR-free coupons, integrated probes, coupon instant off , coupon instant-off with soil tube. We will test and compare each method in this test.3 sizes of coupon and holiday : 5cm2, 30 cm2, 50 cm2

DC current source: It can generate time-constant and time-variant signal, time-constant output voltage: ±3 Vdc; time-variant output voltage: ±15 Vdc by square wave(duration of A:C=5s:15s)Current density: 1A/m2, 5A/m2, and 10A/m2

Resistivity of electrolyte solution :～5 Ω•m,～50Ω•m,～550Ω•m


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Data collection: Recording ON and instant-off potential by a data logger at 1000S/s sampling rate, and a suitable SHUNT will be used to test and calculate current with real value.Reference electrode: SCE is closed to the couponTesting results: fill the table as follow.

Coupon size (cm2)

Instant–off (-mVcse)

IR-free Probe(-mVcse)

Soil tube (-mVcse)

Soil tube with instant-off (-mVcse)

5

30

50

The results under time-variant condition may be fluctuant , so those will be presented by recording curve.


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Outline


- Coupon Edge Effects Testing - Coupon Base Plate Lateral Width Effects Testing - Coupon Coating Under-Cut Effects Testing- Coupon Polarization Characteristics Under Different Orientations / Distance to the



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Coupon Preparation- All coupons and holidays, used in Phase2 will be prepared to SA 2 ½ surface

which is the same surface as used in Phase 1.

- Before lab installation, all coupons will be kept dry and sealed in plastic bag.

- WBE for coating under-cut effects testing will be manufactured with 100×100

beams. The coating under-cut will be pre-manufactured with PVC mold. The

potential can be measured by micro-electrode, and the current on every beam

can be measured respectively by special scanner.

Key Points for Phase 2

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Electrolyte Solution Preparation- The electrolyte solution will be prepared according to real soil in phase 1 by

some chemical reagent, e.g. NaHCO3, CaCl2, MgSO4, KCl

- Cl- is a depolarizer, we will take care to control the Cl- rate in electrolyte

solution.

- If it is possible, we will use a pH meter to measure the pH on the surface of

coupon to check and validate the polarization of coupon.

- Before we perform any testing, the resistivity, temperature and Cl- will be

checked firstly.


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Data Collection and Characterization:

− For Coupon Edge Effects Test

• The micro-region potential scanner may be a innovative device for potential

scanning, the disturbance of potential should be taken into account, the scanning

speed and sampling rate are still unclear, we may need to try more times to confirm

the optimal settings of movement and sampling.

• Although the micro-reference electrode will be used to measure the regional

potential on the coupon in electrolyte solution, but it is still a ON potential, there

may be a little error in potential, which should be taken into account.


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Data Collection and Characterization

− For Polarization Characteristics Under Different Orientations /

Distance to the Pipe

• There are so many testing groups, so we need to make a reasonable adjustment.

When the testing need to be paused, we will keep CP on all the time.


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Outline


- Coupon Edge Effects Testing - Coupon Base Plate Lateral Width Effects Testing - Coupon Coating Under-Cut Effects Testing- Coupon Polarization Characteristics Under Different Orientations / Distance to the



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Schedule for Phase 2

- Before 31/10/2018:Kick-off meeting of Phase 2.

- Before 15/11/2018:Prepare coupons, pipe, RE, and data loggers. etc. for testing in lab

16/11/2018-31/11/2018:- Coupon Edge Effects Testing - Coupon Base Plate Lateral Width Effects Testing- Coupon Coating Under-Cut Effects Testing1/12/2018-15/12/2018: - Coupon Polarization Characteristics Under Different Orientations / Distance

to the Pipe- Pipeline Backfill Soil Effects Testing- Coupons Testing under AC/DC Stray Current Conditions16/12/2018-31/12/2018:Data analyze and Final report for Phase2.

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Thanks

pipeline research council international, inc

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