Support to GOG in integrity assessment of unpiggable ... · Support to GOG in integrity assessment...

ACTIVITY COMPLETION REPORT

Support to GOGC in integrity assessment of unpiggable pipelines

(in the framework of CWP.08.GE)

INOGATE Technical Secretariat and Integrated Programme in support of the Baku Initiative and the Eastern Partnership energy objectives

Contract No 2011/278827

A project within the INOGATE Programme

Implemented by: Ramboll Denmark A/S (lead partner)

EIR Global sprl. The British Standards Institution

LDK Consultants S.A. MVV decon GmbH ICF International

Statistics Denmark Energy Institute Hrvoje Požar

Document title Activity Completion Report "Support to GOGC in integrity assessment of unpiggable pipelines (in the framework of CWP.08.GE)"

Document status Final

Name Date

Prepared by K. C. Lax 26/03/2016

Checked by

Nikos Tsakalidis

Adrian Twomey

March – April 2016

Approved by

Peter Larsen 08/06/ 2016

Revision History

Revision Reason Author Checked Approved Date

0 First issue K. C. Lax R.K.Lindley M.J. Holland 30/03/2016

1 ITS comments K. C. Lax R.K.Lindley M.J. Holland 31/03/2016

2 ITS comments K.C. Lax R.K. Lindley M.J. Holland 01/04/2016

This publication has been produced with the assistance of the European Union. The contents of this publication are the sole responsibility of the authors and can in no way be taken to reflect the views of the European Union.

Abbreviations and acronyms

AC (ac) Alternating Current

ASME American Society of Mechanical Engineers

ACVG Alternating Current Voltage Gradient

DC (dc) Direct Current

DCVG Direct Current Voltage Gradient

ECDA External Corrosion Direct Assessment

CIPS Close Interval Potential Surveys

CP Cathodic Protection

ISO International Organization for Standardization

MAOP Maximum Allowable Operating Pressure

pH A logarithmic measure of the hydrogen ion concentration

PVC Electrical Insulation Tape

Table of Contents 1 PART 1 – EUROPEAN COMMISSION ............................................................................................ 1

1.1 Background ........................................................................................................................ 1

1.2 Essence of the Activity ....................................................................................................... 1

1.3 Key Findings ....................................................................................................................... 2

1.4 Ownership and Benefits of the Activity ............................................................................... 3

1.5 Recommendations ............................................................................................................. 4

1.6 Impact Matrix .................................................................................................................... 4

2 PART 2 - BENEFICIARIES.............................................................................................................. 5

2.1 Executive Summary ............................................................................................................ 5

2.2 Background ........................................................................................................................ 5

2.2.1 Objectives of the study, key findings and recommendations .......................................................... 6

2.2.2 Methodology and outputs ............................................................................................................. 6

2.2.3 Limitations and further work........................................................................................................ 6

2.3 Recommendations ............................................................................................................. 6

2.3.1 Integrity Infrastructure ................................................................................................................ 6

2.3.2 Corrosion Strategy ...................................................................................................................... 7

2.3.3 Repair Procedures ..................................................................................................................... 10

2.3.4 ASME B 31 G Assessment .......................................................................................................... 10

2.3.5 Proactive Approach ................................................................................................................... 10

2.4 ECDA Manual ................................................................................................................... 11

Annex 1. First Mission Report .......................................................................................................... 17

Annex 2. Second Mission Report ...................................................................................................... 24

Annex 3. Bell Hole Reports............................................................................................................... 42

Annex 4. Conceptual Cathodic Protection Design ............................................................................. 50

Annex 5. Priority Matrix- Example.................................................................................................... 51

Annex 6. Workshop material ............................................................................................................ 52

Annex 7. Beneficiary appreciation letter .......................................................................................... 52

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1 PART 1 – EUROPEAN COMMISSION

1.1 Background

Assignment Title: Support to GOGC in integrity assessment of unpiggable pipelines

Country and Dates: Georgia

Beneficiary Organisation(s): Georgian Oil and Gas Corporation

Beneficiary Organisation’s key contact persons – name and e-mail address

Georgian Oil and Gas Corporation (GOGC)

Mr. Tato Guguadze, Deputy Technical Director ([email protected])

Deliverables Produced Classroom and field training. Customized Priority Matrix to enable proactive approach to gas leak prevention.

Expert Team Members K. C. Lax, R. K. Lindley, B.W. Green (Corroconsult UK Ltd)

1.2 Essence of the Activity

The specific objectives of this assignment were to:

Assess and propose the most feasible for the local context methods and technology for

inspection and direct assessment of the unpiggable gas pipelines (focus to be made on the

feasibility of the ECDA method).

Carry out ECDA on a selected section of pipeline to validate the techniques.

Provide training to GOGC's personnel in the inspection and direct assessment of the

unpiggable gas pipelines with focus on the ECDA method. Prepare the manual (guidelines)

for using the ECDA method in Georgia.

These objectives have been addressed by performing the following actions:

1. Introduce the concepts of External Corrosion Defect Assessment (ECDA) as an integral part of

asset management for pipelines.

2. Provide explanations for the benefits and limitations of the various above ground survey

techniques that form part of ECDA.

3. Workshop presentation "Introduction to ECDA".

4. Agree a suitable location for the demonstration and training of personnel in the ECDA

processes on an exposed pipe.

5. Training in ECDA assessment of exposed coating, pipe surface and corrosion damage.

6. Explanation and application of ASME B31 G standard "Remaining strength of corroded

pipelines’’.

7. Training in the application of visco-elastic corrosion protection (coating repair) materials on

exposed pipe before re-burial.

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8. Direct Current Voltage Gradient (DCVG) above ground survey training and defect

assessment.

9. Training in the importance of cathodic protection as a long-term mitigation for external

corrosion.

10. Close-out workshop to emphasize that long-term protection of the pipeline is required after

leak repairs using a combination of visco-elastic corrosion prevention material, mechanical

protection with an overwrap, and the application of cathodic protection.

During the second mission extensive works were carried out on the pilot section to:

Excavate six locations identified from the Priority Matrix;

Evaluate the existing coating;

Prepare the pipe surface for circumferential wall thickness and pit depth measurements;

Restore the corrosion protection coating with Stopaq visco-elastic material and mechanical

overwrap;

Backfill the excavation;

Demonstrate the use of DCVG survey equipment for ECDA on both protected and

unprotected pipelines.

The results of the survey and investigation works on the pilot section are given in Annex 2 Second

Mission Report.

1.3 Key Findings

The key findings of the activity were:

1. GOGC has no written policy or procedures regarding the control of external corrosion on the

North South gas pipeline.

2. GOGC has no written Pipeline Integrity Management Scheme (PIMS).

3. GOGC has no in-house expertise for external corrosion control using either coatings or

cathodic protection.

4. Due to the criticality of gas supply to Armenia there are severe technical and political

constraints on the prompt and effective management of gas leaks.

5. Substantial training in ECDA techniques, coating repair, cathodic protection implementation

and cathodic protection monitoring is recommended.

6. Additions to the work scope were requested by GOGC:

a) Provision of a conceptual cathodic protection system for the pilot section;

b) Develop a generic Priority Matrix specific for GOGC North South Line;

c) Develop a spreadsheet to record and calculate measurements on exposed pipes to comply

with ASME B31 G "Remaining Strength of Corroded Pipelines".

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7. Long-term gas leakage is accepted by GOGC on the grounds that the gas supply can only be

interrupted to allow repairs under special circumstances. Acceptance of gas leaks is

unthinkable within the European Union, and most other parts of the world, on the grounds

of danger to people, harm to the environment and risk of catastrophic explosion.

8. Gas leakage is not quantifiable based on anecdotal evidence and the leaks that were seen

during the first and second missions. The best way to quantify the leakage over the entire

pipeline would be to compare the delivered gas metering records at the Russian border and

the Armenian border. This is outside the remit of the present scope of works.

1.4 Ownership and Benefits of the Activity

The main benefits of the activity for the Beneficiary are:

1. Clear understanding of the requirements for ECDA.

2. Ability to calculate the Maximum Allowable Operating Pressure (MAOP) for a section of

inspected pipeline.

3. Long-term repair techniques to prevent further external corrosion.

4. Understanding of the requirement to apply properly designed cathodic protection systems to

supplement the coating repairs and thus ensure protection against external corrosion.

GOGC (the Beneficiary) were fully engaged in the process of the ECDA works and the subsequent

repairs and have shown a willingness to develop a Pipeline Integrity Management Scheme (PIMS) to

ensure that there is a clear program in place and implemented. The gas experts from GOGC received

on-the job training during the two weeks of ECDA exercises on the selected pilot area (see Annex 3

&4). The representative of EU Delegation to Georgia also took part in one of the training sessions in

the field. In the end of the assignment there was held a one day workshop where the results of the

pilot area assessment have been discussed as well as the GOGC personnel took part in the practical

work of calculation of maximum allowable pressure using the priority matrix (see Annex 5). The

capacity of the GOGC personnel has been strongly increased as a result of the performed pilot

survey, on the job training and the workshop (see Annex 6 for the relevant documents). Participants

have been requested to complete a questionnaire before and after the workshop (ex-ante and ex-

post questionnaire) which mapped out the level of understanding of each individual and served as a

basis on which to compare the knowledge gained after the workshop. The analysis of the responses

show that the participants are fully aware of ECDA method and are able now to perform the works

on their own. The ITS received an appreciation letter from GOGC where the impact and the

ownership is indicated as a result of performed work (see Annex 7).

Given the age and the condition of the pipeline that was the subject of the pilot study it was evident

that a progressive program of inspection, repair, and maintenance is required to maintain the critical

gas supplies of Russian gas from Georgia to Armenia. Although it is not a part of this study it is

evident that GOGC benefits financially and politically by ensuring a secure supply of gas from Russia

to Armenia.

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1.5 Recommendations

The key activities that are recommended for GOGC to manage the gas leakages and continuing

external corrosion damage to the pipeline can be summarized as:

Develop an infrastructure within GOGC to manage the integrity of the pipeline;

Develop a strategy for managing the existing condition of the pipeline;

Coating repairs using non-crosslinkable visco-elastic materials with an overwrap;

Apply cathodic protection system with remote monitoring and control;

Implement repair procedures;

Apply ASME B 31 G criteria to assess the safe operating condition of the pipeline;

Become proactive rather than reactive in dealing with gas leakages.

1.6 Impact Matrix

Impact Area Developments 2012 (%) 2016 (%)

Integrity infrastructure implementation

Department within the GOGC dedicated to pipeline integrity

20% 90%

Corrosion strategy Develop and implement a corrosion strategy

25% 75%

Repair procedures Implement new repair procedures 25% 75%

Pipe assessment ASME B31 G procedures adopted 0% 100%

Proactive approach Improve pipeline before incidents occur. Apply cathodic protection.

10% 90%

Environment Fewer leaks. Less environmental impact 15% 85%

Economics Fewer leaks mean fewer interruptions to supply and less loss of product.

No information

No information

Social Fewer interventions means less disruption to communities

20% 80%

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2 PART 2 - BENEFICIARIES

2.1 Executive Summary

The specific objectives of the missions were:

Assess and propose the most feasible for the local context methods and technology for

inspection and direct assessment of the unpiggable gas pipelines (focus to be made on the

feasibility of the ECDA method).

Carry out ECDA on a selected section of pipeline to validate the techniques.

Provide training to GOGC's personnel in the inspection and direct assessment of the

unpiggable gas pipelines with focus on the ECDA method. Prepare the manual (guidelines)

for using the ECDA method in Georgia.

During the course of the two missions GOGC requested additional information/training and

assistance beyond the original objectives, and this additional information and training was provided.

2.2 Background

GOGC are responsible for operation and maintenance of the North-South pipeline that runs from the

Russian border in the North to the Armenian border in the South. The pipeline carries the only supply

of gas that there is to Armenia. This means that the supply of gas is politically sensitive as well as

being essential for the wellbeing of the population of Armenia.

The pipeline is 48 years old and has never had a fully functional external corrosion system. Internal

corrosion risks are considered negligible since the gas is dry and non-corrosive.

Because of its age and hence lack of facilities, the pipeline cannot be inspected internally using a

pipeline inspection tool (also known as a pig). It is also likely that the geometry of the pipeline may

preclude the use of an internal inspection due to dents, bends, and possible valve intrusions.

Internal inspection tools can, amongst other things, detect and measure both internal and external

corrosion over the entire length of the pipeline.

To achieve a similar result for external corrosion defects using only above ground survey techniques

requires the use of different techniques and skill to interpret the results from those measurements.

Collectively these techniques and the analysis of the results are known as External Corrosion Direct

Assessment (ECDA).

GOGC have acquired a number of the instruments required to perform these works. These include:

Direct Current Voltage Gradient (DCVG) equipment;

Pipe and depth location systems;

Alternating Current Voltage Gradient (ACVG) equipment;

Cathodic protection instrumentation and reference electrodes;

Ground penetrating radar (GPR);

Soil resistivity measuring system (Wenner 4 pin);

6

Ultrasonic pipe wall thickness measuring instruments;

High voltage coating defect detectors.

Without a documented strategy, written procedures and interpretation skills the equipment is

of limited value.

2.2.1 Objectives of the study, key findings and recommendations

The objectives of the study have been fulfilled completely. GOGC are now able to apply the principles

to develop their own Pipeline Integrity Management Scheme and implement a program of

inspection, maintenance, and repair.

The practical demonstrations of the principles and the hands-on training have given the GOGC staff

the necessary confidence to progress to the next step in their development.

2.2.2 Methodology and outputs

The approach involved a mixture of presentations and field work to demonstrate the principles of

ECDA. This report, combined with the documentation and training provided constitutes a manual to

enable GOGC to develop their integrity management scheme and apply it.

2.2.3 Limitations and further work

It is not possible to equip anyone with the skills developed by experience in ECDA and pipeline repair

in a short period of time. Nevertheless, the combination of the detailed presentations, with question

and answer sessions, and the participation of GOGC personnel in the field work will enable the GOGC

to move on and develop their own systems.

2.3 Recommendations

The key activities that are recommended for GOGC to manage the gas leakages and continuing

external corrosion damage to the pipeline can be summarized as:

Develop an infrastructure within GOGC to manage the integrity of the pipeline;

Develop a strategy for managing the existing condition of the pipeline;

Coating repairs using non-cross linkable visco-elastic materials with an overwrap;

Apply cathodic protection system with remote monitoring and control;

Implement repair procedures;

Apply ASME B 31 G criteria to assess the safe operating condition of the pipeline;

Become proactive rather than reactive in dealing with gas leakages.

2.3.1 Integrity Infrastructure

Within GOGC there does not appear to be an infrastructure to deal exclusively with pipeline integrity

issues. A department with sole responsibility for the development and implementation of integrity

strategies would be of benefit.

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A department with the sole responsibility for integrity would enable a focused approach to the

required training/education and management of the issues. External advice should be sought to

support the Integrity Group with the necessary training and assistance with the implementation e.g.

risk assessment, cathodic protection etc.

2.3.2 Corrosion Strategy

The corrosion control strategy is not well-formed or documented. Great reliance is placed upon

monitoring of cathodic protection by personnel who do not have the required skill levels to

undertake anything more than simple readings. The validity of the collected data cannot be verified

with the existing skill levels. Written procedures and method statements are required to ensure that

the methodology for the measurements and assessments is validated.

Principle activities that require method statements, procedures, and operating training are:

ON and OFF potential measurements at test posts:

o Reference electrode calibration;

o Placement of reference electrode;

o Importance of polarities;

o Interpretation of results to determine acceptability;

o Dealing with a.c. interference;

o Dealing with d.c. interference;

o Dealing with telluric interference.

Transformer-rectifier measurements and tests:

o Voltage output;

o Current output;

o Electrical condition.

Close Interval Potential Surveys (CIPS) measuring ON and OFF potentials:

o System set-up;

o Calibration;

o Defect identification;

o Correlation with DCVG results.

Installation and measurements of coupons:

o Current density (a.c. and d.c.);

o ON and OFF potentials;

o A.C. potentials.

Direct Current Voltage Gradient surveys (DCVG):

o System set-up for cathodically protected sections;

o System set-up for unprotected sections;

o Defect location;

o Defect classification (% severity).

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Alternating Current Surveys (ACVG):

o System set-up;

o Interpretation of results;

o System limitations.

Cased crossings:

o Determining whether an undesirable contact exists between carrier pipe and

casing;

o Corrosion risks inside casings;

o Cleaning casing annulus;

o Filling annulus with non-crosslinkable visco-elastic casing filler to prevent

corrosion inside casing to carrier and casing;

o Replacing end-seals;

o Potential measurements of carrier and casing.

Installation of cathodic protection system elements:

o Impressed current anode horizontal groundbeds;

o Impressed current vertical anode groundbeds;

o Linear polymeric anodes;

o Galvanic anodes;

o Test posts for potential monitoring and bonding.

Populating the Priority Matrix.

Inspection, preparation and repair of exposed sections:

o Coating inspection;

o Coating removal;

o Measurement grid mark-up;

o Ultrasonic measurements;

o Pit depth measurements;

o Repair/replacement of coating using non-crosslinkable visco-elastic and

overwrap

o pH measurements;

o Soil resistivity measurements (Wenner 4 pin).

A Corrosion Strategy is required to drive the entire Integrity process. The Corrosion Strategy should

be prepared, initially with the assistance of an external Consultant, which covers the particular

requirements of aged pipelines under the control of GOGC. The Corrosion Strategy should serve to

change the way that GOGC view, and manage, the corrosion risks. A proactive approach is required

rather than a reactive approach. In particular the strategy should be emphatic about the requirement

to make every repair with a view to the long-term performance of the pipeline so that once a section

has been repaired and cathodically protected it becomes part of the regular monitoring and will

require no further interventions. In this way the pipeline will gradually be returned to safe operation

with an increased reliability.

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It is noted that there numerous above-ground sections that also require intervention to prevent

further deterioration and possible leakage risk. An example of this would be the Kura River crossing

that was a part of the pilot section. The aerial crossing section has shifted on the support bases and

should be restored to the original condition and eliminate unnecessary mechanical strain on the

pipeline as well as the risk of erosion caused by movement of the pipe on the support features.

Photographs of Kura River Aerial Crossing

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2.3.3 Repair Procedures

After any section of the pipeline has been exposed the coating should be repaired / replaced. The

existing PVC tape wrap is insufficient to provide continuing long-term protection. To ensure quality

in the repair of the section it is required to instigate procedures for the repair crew to follow. There

is evidence that in the past the pipe has not been protected from continuing external corrosion

after repairs have been carried out.

The coating repair procedures should include:

Surface preparation;

Application of non-crosslinkable visco-elastic corrosion protection material;

Application of an overwrap to provide mechanical protection.

There are already procedures in place within GOGC for the repair of leaks and this could be

supplemented by external strengthening in areas where the wall thickness is considered to be

insufficient or marginal. External strengthening could be in the form of proprietary wrap-around

composites. The corrosion protection does not add mechanical strength to the pipe it prevents

further weakening of the pipe.

2.3.4 ASME B 31 G Assessment

ASME B 31 G provides an industry accepted standard to determine the acceptable extent of pit

depths and wall loss. It is sometimes criticized as being too conservative an approach, but is

considered to be entirely appropriate for ageing pipelines with no historical records of corrosion

protection or leak history.

During the second mission the principles that were explained during the first mission were

developed and demonstrated. GOGC embraced the technique and undertook many of the

measurements under the supervision of the Corroconsult specialist Engineer. The results were

processed on an Excel spreadsheet and are presented in Annex 2.

Results from the measurements and ASME B 31 G assessment were further categorized into three

levels of inspection to suit the GOGC requirements. Each set of readings was assessed to see if it

met the requirements of the successive levels of acceptance.

2.3.5 Proactive Approach

The East-West line is cathodically protected and GOGC undertake routine monitoring of the

cathodic protection ON potentials and transformer-rectifier status. The East-West line is not a part

of the pilot study. The pilot study was carried out on the North-South line, where there is presently

no cathodic protection.

In the absence of documented and formal strategies the two missions formed the impression that

GOGC react only to critical incidents that could impact on the political and fiscal implications of an

interruption to the gas supply to Armenia.

All gas leaks should be repaired immediately.

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A change in the approach to the issues of gas leaks is required. Instead of just reacting to the issues

it is required to predict where the issues could occur and take the necessary steps to see that they

do not. This approach may not have much impact initially, but over time there will be a gradual

decline in the number of incidents. The improvements in repair technology will avoid future

corrosion and eliminate the need to re-visit the same area to repair more leaks.

2.4 ECDA Manual

INSPECTION AND DIRECT ASSESSMENT FOR UNPIGGABLE GAS PIPELINES IN GEORGIA

EXTERNAL CORROSION DEFECT ASSESSMENT MANUAL

References

Source Number Title

CENELEC 15280 Evaluation of a.c. corrosion likelihood of buried pipelines applicable to cathodically protected pipelines

ASME B 31 G Manual for determining the remaining strength of corroded pipelines

CENELEC 50162 Protection against corrosion by stray current from direct current systems

CEN 12501-2 Corrosion likelihood in soil

CEN 15257 Competence levels and certification of cathodic protection personnel

NACE RP0502 Pipeline external corrosion direct assessment methodology

ISO 16440:2016 Design, construction and maintenance of steel cased pipelines

Scope

The ECDA manual is provided as a part of the scope of work in the framework of CWP.08.GE. An

overview of the ECDA process is provided but not detailed operating instructions and calculation

methodologies. These functions are adequately described in the standards and guidelines that are

referenced in the manual.

The applications are restricted to pipelines buried in soil, although there may be short river crossing

sections.

Background

Buried pipelines are protected from external corrosion by a combination of coatings and cathodic

protection. In this context a coating is any material applied to the pipe with the purpose of reducing

the risk of external corrosion.

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Typical coatings that are anticipated in Georgia are:

Fusion bonded epoxy (FBE);

Three layer polyethylene (3LPE);

Coal tar enamel;

Tape wrap;

Non-crosslinkable visco-elastic.

Coatings are often referred to as passive corrosion protection and cathodic protection as active

corrosion protection.

The corrosion process is inextricably associated with a flow of current from the pipe into the soil.

The corrosion process is described in many text books and standards and will not be elaborated upon

here, except to say that the magnitude of the flow of current is directly related to the loss of metal.

The corrosion rate is governed by Faraday's Law, which states that a current of 1 ampere, leaving a

carbon steel pipe and flowing into the surrounding electrolyte (e.g. the soil) for a period of 1 year will

consume 9.1 kg of steel.

Coatings are applied to provide a resistance to the flow of current from the pipe. Any flaws in the

coating will allow current to flow and hence corrosion to take place. There are many ways in which

the performance of a coating as an effective resistance to current flow can be affected.

A detailed explanation of coating failure mechanisms is beyond the scope of this manual but some

key features that are necessary for the effective performance of a coating as a corrosion barrier are:

Compatibility with the anticipated operating temperature of the pipe.

Resistant to damage from the environmental conditions:

o Effects of pollutants;

o Mechanical damage (e.g. boulders in rivers and streams);

o Flora and fauna.

Correct application in the factory or mill.

Correct field application at field joints:

o Surface preparation o Primer application (if primer required);

o Pipe profile with suitable material (e.g. visco-elastic);

o Correct ambient conditions at the time of application: Temperature;

Dew point;

Dust;

Precipitation;

Pre-heating (if required);

Curing time;

Applicator competence;

Tape overlap (at least 50%).

Natural ageing of the coating.

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Except for short sections of pipe, prepared under carefully controlled conditions, it is unrealistic to

expect a perfect coating. For this reason the corrosion protection properties of the coating are

supplemented by the application of cathodic protection.

Cathodic protection is an electro-chemical technique that applies current that flow on to the pipe to

counteract the current that is flowing off the pipe. Theoretically it is possible to protect a pipeline

with cathodic protection that has no coating at all. Indeed, structures that are totally immersed in

water are protected in this way.

It is logical to assume that the more bare steel that is in contact with the soil then the greater the

cathodic protection current is required. There are many text books and standards that deal with the

subject of cathodic protection and this manual will only deal with the practical applications required

to test the satisfactory performance of an installed cathodic protection system.

Even cathodic protection that is not 100% effective can still significantly reduce the corrosion rate.

This is an important point since cathodic protection may be the only practical thing that can be

achieved on some sections of pipeline that cannot be accessed for coating repair (e.g. river

crossings).

External Corrosion Direct Assessment (ECDA)

The purpose of ECDA is to establish whether or not the pipeline is in a fit condition to continue

operating and what remedial measures are required to maintain that fitness.

In the absence of other influences the corrosion risks will exist at coating defects that are not

cathodically protected. ECDA, therefore is focussed on techniques to locate the coating defects, and

then to evaluate their severity.

Description of the ECDA defect location techniques

The techniques can be broadly separated into three categories:

Category 1: Holiday detection of exposed coating using a high voltage source.

Category 2: Location of coating defects with the aid of an applied signal (a.c. or d.c.).

Category 3: Measurement of pipe-to-soil potentials.

High Voltage holiday detection

This technique is used on exposed pipe and works by effectively testing the dielectric strength of the

coating by applying a high voltage. Dielectric strength is an indication of the ability of an insulator to

withstand a voltage, so indirectly it can assess the resistance of the coating. Care is required in the

application of this technique because there is a risk of damaging good coating by incorrect voltage

selection and speed of measurement.

The coating manufacturer's data sheet should be consulted to determine the correct test voltage. If

that is not available then a useful guideline is given in ISO 21809-3 for different coating types and a

recommended scan speed of no greater than 300 mm per second.

Note that this device is not suitable for use on wet surfaces.

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Applied Signal

Applying a signal to the pipe and tracing the effects of the signal can locate coating defects

accurately. Sizing them, or quantifying the severity, is not so simple.

A.C. signal devices inject a signal with a known frequency and evaluate the strength of the signal

along the pipeline. The signal will be attenuated where the coating is defective because the signal will

take the lower resistance path through the earth rather than through the pipeline. The attenuation

characteristics are different for different frequencies and the manufacturer's recommendations

should be followed to establish the correct frequency for the pipeline coating under evaluation.

Generally speaking a.c. injection devices are better suited to locating general areas of poor coating,

rather than discrete coating damage.

D.C. signal devices include Direct Current Voltage Gradient (DCVG) and Close Interval Potential

Surveys (CIPS).

DCVG systems require a d.c. source to interrupt so that the operator can observe the voltage gradient

of the applied d.c. signal. Usually the d.c. source is an existing cathodic protection system.

If there is no permanent cathodic protection system then a temporary system can be applied using a

d.c. voltage source and a temporary anode groundbed.

The d.c. source is interrupted with cyclic switcher. The switcher is set to a fast cycle, typically 0.3

seconds n and 0.6 seconds off. The cycle period is not usually critical but it is important to be able to

recognize what constitutes an ON signal and what constitutes an OFF signal when observing the

instruments. Probes are placed in the ground to measure the voltage gradient. Where the current

enters the pipeline represents a coating defect and is easily detected on the mobile instrument.

Once located the coating is assessed by measuring the potential to remote earth and the potential at

the epicentre of the coating defect. The severity is expressed as a %IR. The manufacturer's

instructions should be followed for system set-up and operation. The survey results and

interpretation are very much operator dependent and it is essential that the operators are skilled in

the set-up, application, and interpretation of the results. A formal training course is a pre-requisite

before the operator can be considered competent to carry out a survey.

Measurement of pipe-to-soil potentials

CIPS surveys are carried out only on pipelines that have an established cathodic protection system.

The survey measures the pipe-to-soil potentials over the entire pipeline at close intervals

(approximately every 2 m for cross-country pipelines). The cathodic protection sources of power are

synchronously interrupted using satellite controlled switchers and the mobile potential measuring

devices is synchronised to the same source. In this way accurate ON and OFF potential

measurements can be recorded. These values can be compared with the prescribed limits given is

ISO 15809-1 (or other cathodic protection standards) to determine whether or not the pipeline is

cathodically protected. If the data is plotted on an XY graph it is possible to detect coating defects by

looking for marked changes of polarity in the positive (anodic) direction.

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ECDA Assessment Techniques

The difficulty in determining where to excavate when there are many indications of coating failure

and/or cathodic protection anomalies can be overcome by using a Priority Matrix. A Priority Matrix

employs simplistic Bayesian logic to establish locations that are statistically significant based on a

number of factors. During the Mission visits to GOGC a Priority Matrix template was created and has

been supplied in electronic form.

It is good practice to also excavate a location where the Priority Matrix indicates that there is a low

risk of corrosion damage. This location is a Control Location and serves as a benchmark to confirm

that the Priority Matrix is meaningful. If, for example, corrosion is detected at the Control Location

then it indicates that the Priority Matrix weighting values require adjustment.

Once the locations have been determined, and the pipe exposed, there are a number of assessments

that should be carried out.

The assessments that are required are scheduled in the electronic reporting form that has been

provided to GOGC. The form uses the collected information to calculate the maximum allowable

operating pressure (MAOP) that the corroded pipe is capable of handling. The calculation

methodology utilised in the reporting form is from ASME B 31 G.

If it is not practical to undertake any excavations then the best principle is to verify that the cathodic

protection is effective at the areas identified as having coating failures.

Other Measurements

Other measurements that can be used to help populate the Priority Matrix and assist in the

assessment of the defect severity include:

Wenner 4 pin soil resistivity (useful for corrosion likelihood assessment);

Soil pH;

Sulphate reducing bacteria (culture kit);

A.C. interference (recorded with a data logger e.g. Weilekes MiniLog);

D.C. interference (recorded with data logger e.g. Weilekes MiniLog);

Transformer-rectifier current and voltage output.

Coating Repairs

To accommodate the varying types of coating that may be encountered on Georgian Pipelines and

the requirement for ease of application it is recommended that the coating repair materials be

standardized. The recommended material is an amorphous, non-crosslinkable visco-elastic. This is

readily available in Georgia and the product has a long shelf-life. Training in all aspects of the product

can be arranged by the Georgian distributor.

16

Casings

Casings, also known as sleeved crossings, are a particular risk for pipelines because of the uncertainty

they create. The uncertainty is caused by the inability to inspect the pipe within the sleeve and the

high consequence of failure of the pipe.

The recommendations are that wherever possible sleeved crossings and casings should be avoided.

It is recognized that in Georgia there are cased crossings that have been poorly constructed.

A carrier pipe within a sleeve should be electrically isolated from the sleeve and there should be no

conducting medium within the sleeve. In Georgia the electrical separation has been attempted by

pushing wooden wedges between the carrier pipe and the sleeve at the ends of the sleeve. The wood

soon becomes saturated and conductive and if the crossing is sufficiently long the carrier pipe can

sag and make contact with the sleeve.

Measurements in accordance with ISO 16440:2016 Design, construction and maintenance of steel

cased pipelines should be carried out.

It is recommended that since the cased crossings are in-situ and poorly constructed that a separate

intervention program is established. This program will have the aim of substantially reducing the

corrosion risks to the carrier pipe within the sleeve. The methodology can include steps such as:

Expose both ends of the crossing;

Temporarily support the carrier pipe;

Remove any supports (wood or steel);

Water blast any detritus within the sleeve;

Install insulating spacers with the use of hydraulic rams (coating damage is not important);

Install a vent pipe/filler at either end of the sleeve (at the top at one end and at the bottom

at the other end);

Apply high quality casing end seals with additional Stopaq material;

Fill the sleeve with Stopaq casing filler.

The casing filler will provide external protection to the carrier pipe and internal protection for the

sleeve pipe for a minimum of 30 years and requires no maintenance or inspection.

Competence of Personnel

As with any other technical task carried out on live pipelines it is important that the personnel are

competent to undertake the prescribed tasks. This is particularly important where the application

and interpretation of the survey results is operator dependent. European Standard EN15257 provides

guidance for cathodic protection applications and these guidelines can be extended to include CIPS

and DCVG surveys.

17

Annex 1. First Mission Report

Mission to Tbilisi from 18 January 2016 to 22 January 2016

Report by K. C. Lax, Corroconsult UK Ltd

1. Background

Project number 2011/278827 within the INOGATE program is to provide support to the Georgian Oil

and Gas Corporation (GOGC) in the integrity assessment of unpiggable pipelines. Corroconsult UK

Limited have been contracted to provide this technical support.

The technical support is to be provided in two phases, or missions. The first mission was for the

provision of documentation, review of data, and carry out a site visit for the proposed pilot study.

2. Visit dates

A Consulting Engineer visited the offices of GOGC and travelled the entire proposed pilot section area

between 18 January and 22 January 2016 inclusive.

3. Organization visited

Office visits were carried out at the GOGC head office in Tbilisi. The pilot study site was between KP

57 and KP 49 on the North South gas pipeline that runs from Russia to Armenia.

4. Participants

The office participants, who all attended the Intriduction to ECDA Seminar were:

1. David Klibadze - technical monitoring group;

2. George Zaqarashvili - technical monitoring group;

3. Tamaz Shanidze - technical monitoring group;

4. Niko Gogoladze- technical monitoring group;

5. Irakli Kapanadze- technical monitoring group;

6. Kakhaber Daneli- technical monitoring group;

7. Isidore Tsiklauri - expert in electricity chemical dept;

8. Anton Goguadze -deputy chief of technical department at GOGC;

9. Nikos Tsakalidis - INOGATE deputy team leader;

10. Rusudan Nonikashvili - INOGATE communication expert.

The site visit was attended by Anton Goguadze and David Klibadze plus six members of the

monitoring team.

18

5. Discussions and Findings

The notes for each day's activities are copied in Appendix A.

A tabular summary of the First Mission Deliverables and the status at the end of the visit is given in

Table 1: Summary of deliverables for first mission.

No. Activity Action Status

1 Review technical

characteristics of the

pipeline

Office meetings and site visit Complete

2

(a) Examine pipeline route maps and topography;

(b) Create a pipeline profile

(a) Office meeting and site visit;

(b) Awaiting information from GOGC

(a) Complete (b) On hold. No

impact on future program

3 Determine current local

practices for ECDA

Office meetings and

discussions with field staff Complete

4 Determine suitable way

forward Review of data Complete

It had been proposed that the second phase would comprise of examining and repairing sections of

the pilot length. This would include transfer of knowledge as to how to calculate the Maximum

Allowable Operating Pressure (MAOP) based on pipe surface measurements. Coating repairs will be

made using modern technlogy viso-elastic anti-corrosion materials. An Introduction to ECDA seminar

was presented and during this presentation is was evident that:

GOGC personnel were already trained and competent in the use of the requisite techniques;

GOGC has purchased instrumentation to carry out ECDA;

GOGC required only some minor additional instruction in the evaluation of the collected

data;

GOGC had no knowledge of how to assess the remaining strength of corroded pipelines.

Corroconsult proposed, and GOGC accepted, that they would concentrate on training GOGC

personnel on how to correctly assess the condition of the pipe once it is exposed. Corroconsult would

also provide the additional training required for the above ground surveys.

During the site visit the location excavations were agreed with GOGC. See Annex B for photographs

and maps.

6. Next Steps

Phase 2 is scheduled to commence 21 February and last until 06 March 2016. A separate report will

be prepared for Phase 2.

19

Annex 1.1 Inspection and Direct Assessment for Unpiggable Gas Pipelines in Georgia - Daily Reports

GEORGIAN OIL AND GAS CORPORATION - MEETING NOTES

Tbilisi, 18 January 2016

Attendees: Zakaria Avaliani, Technical Director; Tato Goguadze, Head of Construction

Supervision: Nikos Tsakalidis, INOGATE. Ken Lax, Corroconsult

Notes:

1. Some pipes were constructed during 1955-57. The newest is 1989.

2. Re-hab. Program started 5 years ago.

3. Diameters vary between:

a) 200 mm - Russia to Armenia;

b) 700 mm-Majority of lines;

c) 500 mm;

d) 300 mm.

4. For this project the line under consideration is the East-West line, which is 700 mm diameter.

Mostly constructed in 1967 but some parts were constructed in 1980.

5. There is a 14 km non-operating section which is unpiggable. Although the line was cleaned

and the pigs propelled by compressed air the ovality of the pipe and the sharp bends pre-

vented pigs from running and stuck pigs had to be removed.

6. 60 km of the East-West pipe is still in operation. The pipe cannot be stopped. Present operat-

ing pressure is 15 bar. Design pressure is 55 bar. Need to operate at around 25 - 30 bar.

7. There is no CP on the pipeline.

8. Saguramo is a hub and is near Tbilisi.

9. Agreed to focus attention on the 23 km section of pipe near to Saguramo for this project.

10. Question was asked whether or not CP is essential for ECDA. KCL advised that ECDA compris-

es a number of techniques and if CP is not available then there are other techniques that can

be used.

11. ZA advised that the coating within the section is all bad and that they have carried out an

ACVG survey. KCL agreed that ACVG, DCVG and CIPS were not sensible ECDA options at this

stage.

12. KCL requested additional information to enable a desk top study to be completed in order to

establish locations for bell hole excavations to enable:

a) coating inspection/evaluation;

20

b) pipe circumference measurements,

c) wall thickness measurements,

d) pit depth and location measurements.

13. Coating repairs to be made with Stopaq visco-elastic to ensure compatibility with adjacent

parent coating/tape. If additional strength required then a fibreglass outerwrap will be add-

ed.

14. Next meeting 1000 hours 20 January, at which time ZA will produce data requested and KCL

will provide the proposed program of works for this visit.


Attendees: Tato Goguadze, Head of Construction Supervision. David Inspection Manager.

Supervision: Nikos Tsakalidis, INOGATE. Ken Lax, Corroconsult

Notes:

1. Proposed pilot study site has been changed to the North South line because they have al-

ready decided to replace the section on the East West line.

2. Location is at Gardobani between KP 57 and 43.

3. Generally low lying and wetland area

4. D.C. railway crossing at KP 57.

5. Leakage history.

6. No profile available yet but will do for tomorrow.

7. All other information will also be provided for tomorrow (casings, crossings, leakage loca-

tions.

8. Pipeline depth of burial is no greater than 1 m.

9. Excavations quick and easy to achieve. About 3 hours per excavation.

10. KCL explained that it was important that the responsibilities of INOGATE were fulfilled but al-

so that GOGC achieved the maximum benefit from the transfer of knowledge from Corro-

consult. To do this within the project timeframe we need to plan the time so that all objec-

tives are met.

11. KCL observed that it seems as though GOGC are well equipped to carry out ECDA above

ground surveys but there was a lack of procedural discipline and training for the actual pipe

examination, calculations, archiving and reporting.

12. On this basis KCL proposed:

a) He will present a classroom course "Introduction to ECDA" on Thursday 21 January 2016;

21

b) During the presentation he will deal with specific equipment queries from GOGC to make

sure that only key points were covered during the second visit;

c) The pilot study will not utilise all of the survey skills, since the general condition is known and

there is easy access for excavations;

d) It is anticipated that at least 6 bellhole excavations will be made during Phase 2 and at each

one of the excavations Corroconsult Engineers will provide on-site training for GOGC staff:

i. How to evaluate coating condition

ii. Removal of coating

iii. Preparation of steel surface

iv. Grid marking on pipe

v. Wall thickness and pit depth measurements

vi. Measurement of corrosion extent

vii. Completion of site excavation report

viii. Calculation of MAOP

ix. Re-coating of exposed pipe using visco-elastic materials and overwrap

13. Soil resistivity measurements will be made during the pilot survey and suitable locations to

determine suitable anode groundbed locations.

14. A suitable location for the cathodic protection power supply will be identified during the pi-

lot study.

15. Corroconsult will prepare a cathodic protection system design, including specifications,

which will include remote monitoring and remote control.

16. TG advised that the cost per metre to lay a 720 mm pipe is about $350.00 in Georgia and he

anticipates that a 1000mm line would be at least double that.


Attendees: Tato Goguadze, Head of Construction Supervision;

Nikos Tsakalidis, INOGATE. Ken Lax, Corroconsult;

David Klibadze - technical monitoring group;

George Zaqarashvili - technical monitoring group;

Tamaz Shanidze - technical monitoring group;

Niko Gogoladze- technical monitoring group;

Irakli kapanadze- technical monitoring group;

Kakhaber Daneli- technical monitoring group;

Isidore Tsiklauri - expert in electricity chemical dept;

Anton Goguadze -deputy chief of technical department at GOGC;

Rusudan Nonikashvili - INOGATE communication expert.

22

Notes:

A presentation was provided to the attendees by KCL, with Georgian Translation arranged by

INOGATE. The presentation was entitled "An Introduction to ECDA".

The presentation focused on the actual requirements for the proposed ECDA on the North-South

line.

No further information was provided on the line, but the site visit is confirmed for tomorrow.

The presentation was not a power point and required active participation and attention to the

presentation. All attendees participated well and there were some good questions at the end of the

session. The entire presentation and questions lasted two hours.

A copy of the presentation will form a part of the final report and will be passed to the beneficiary.


Attendees: Tato Goguadze, Head of Construction Supervision;

David Klibadze - technical monitoring group;

Plus 6 others.

Notes:

A visit to the agreed site for the pilot study was undertaken. There were three vehicles involved and

the attendees were knowledgeable about the pipeline route and its history.

During the site investigation six locations were agreed upon and chosen for excavation.

The survey started at KP 57. It was confirmed that in this section there were 13 known locations

where leakage had occurred. Of these 13 locations 10 had been repaired and 3 were waiting for a

period of pressure reduction to be repaired. At some of the locations there were as many as 25 holes.

Repair is made by welding a plate over the hole and wrapping the exposed section with a two layer

tape. The first layer being a thin adhesive and the second being a PVC overwrap. There were no

photographs or documented reports of the repairs although the person who carried out the repairs

said that the holes were all the same - the hole was the same size as the defect in an otherwise intact

coating.

It was confirmed that GTC undertaken the routine measurements on behalf of GOGC.

KP 57

Railway crossing. The railway is d.c. electrified and it is the main Baku-Tbilisi line. Good bonds were

noted at the crossing area. The pipe is cased for a distance of at least 25 m either side of the twin

railway lines. This would make the cased crossing about 55 m long. The casing ends were not visible.

There was one vent pipe. It is very tall and can be as much as 5 m from the actual casing.

The casings were made in the Russian style and there are no separators, just a baulk of timber

rammed in at each end. Casing end-seals are PVC tape.

North of the crossing a section of pipe has been replaced and an isolation joint has been installed at

23

each end of the new section. The new section is protected with magnesium galvanic anodes. Pipe-

to-soil potentials at the test post are around -1.2 V, and mid-way between the 1 km spaced test posts

the most positive measured potential is -0.95 V.

Excavation Location 1

Close to an existing, defunct, CP test post. Approximate KP 55.5. Opportunity will be taken to

investigate the reason for the TP failure and make replace it with a functioning TP.


Approximately 80 m further south from Location 1. There is a 90 degree bend here and hence a

mechanically weak point.


Approximately 5 to 10 m north of the leak in the ditch. Approximately KP 54.7


About 20 m South of the white bag marking a previous repair location.


KP 51.4. This is an exposed section of pipe. Wall thickness measurements were taken, 11.5 mm


KP 49. Just south of the casing vent.

There is a river crossing at KP 46.4 where the pipe is severely dented. During construction they ran

out of pipe and used a damaged section. Wall thickness measured as 11.43 mm. The pipe cover is

less than 1 m and concrete slabs have been installed to protect the pipe.

The pipe continues through a national park, Arghvatili, and much of it is above ground. The Kura River

crossing is also aerial.

There is evidence of significant movement and damage to some sections of the pipe and the trestles.

TG advised that he will mark up the agreed locations on a Google map and provide the raw files to

INOGATE to use.

It was agreed that TG will undertake soil resistivity measurements at a depth of 1 m at the locations

selected for excavation. Additionally a team will undertake a profile survey.

A functioning power supply located on the East West line was visited. The unit is of Russian

manufacture. The rating label states - Primary a.c. voltage is 10kV, secondary a.c. voltage 48 V.

Measured d.c. output is less than the a.c. voltage on the output terminals e.g. 16 V d.c. and 24 V a.c.

This can be investigated during the mission, if time permits.

24

Annex 2. Second Mission Report

Second Mission Report

INTEGRITY (ECDA) ASSESSMENT OF UNPIGGABLE PIPELINES - GEORGIAN OIL AND GAS CORPORTATION (GOGC)

1. Introduction

This report details the findings of the second mission of part of the integrity (ECDA) assessment of

unpiggable pipelines project for GOGC (Georgian Oil and Gas Corporation).

2. Bellhole Excavation Assessment / Training

2.1. Overview

Excavations were undertaken at the locations determined from the priority matrix created by Ken Lax

during the first mission site visit for the pilot area. The locations selected for excavation are

illustrated in this Goole Earth image;

Site works started at Bellhole 001 on Tuesday 23 February 2016 and were completed at Bellhole 006

on Wednesday 02 March 2016.

2.2. Assessment Methodology

In order to allow GOGC to analyse their own future measurements, an adapted interpretation of

ASME B31G has been translated into three levels;

Level 1: Assessment based on measured UT Wall Thickness:

o <10% Wall Loss at all measurements = PASS ;

o 10-80% Wall loss at any single measurement = LEVEL 2 REQUIRED ;

o >80% Wall loss at any single measurement = REPAIR / REPLACE.

25

Level 2: Assessment based on Longitudinal Length & Depth of Interactive Pits:

o Measurement less than allowable length for depth = PASS ;

o Measurement greater than allowable length for depth = LEVEL 3 REQUIRED .

Level 3: Assessment by comparison of operating pressure to MAOP:

o Calculated MAOP greater than Operating Pressure = PASS ;

o Calculated MAOP less than or equal to Operating Pressure = REPAIR / REPLACE.

2.3. Summary of Results

The following table summarises the findings for the excavations completed, full records (where applicable) are included within Appendix A.

GOGC Assessment Level

Level 1 Level 2 Level 3

Bellhole 001 FAIL FAIL PASS

Bellhole 002 FAIL PASS -

Bellhole 003 N/A - Leaks Identified

Bellhole 004 PASS - -

Bellhole 005 FAIL PASS -

Bellhole 006 N/A - Excavation Flooded by Adjacent Canal

3. DCVG Survey Technique / Training

3.1. Overview

DCVG Training was provided to GOGC personnel on Thursday 03 March 2016. The training was

intended to cover the basic field techniques, theoretical principals and record keeping.

Calculations of DCVG results for %IR at Defect analysis were also demonstrated.

As GOGC operated pipelines existing both with and without cathodic protection, techniques were

demonstrated for both.

The current interrupter included with the DCVG kit is polarity sensitive, and as such techniques have

been demonstrated with the interrupter in either leg (positive or negative) of the CP circuit.

3.2. Existing ICCP system

3.2.1. Summary

Utilising an existing transformer-rectifier, isolate the mains supply. Disconnect and install the current

interrupter on either the positive or negative cable in accordance with the diagrams provided.

Reinstate the mains power supply and ensure that the interrupter is turned on. Check the nearest

available test post for the starting signal strength. If necessary adjust the output of the TR to provide

sufficient signal strength for the length of the intended survey.

Where multiple transformer-rectifiers provide cathodic protection to the pipeline under survey, other

26

TRs should be isolated at the TR nearest the area of survey interrupted for the duration of the survey.

It is imperative that all TRs are left re-energised and with their original current outputs when the

surveys are completed.

3.2.2. Overview Diagram

3.2.2.1 Interrupter in TR Positive

3.2.22 Interrupter in TR Negative

27

3.3. Temporary ICCP System

3.3.1 Summary

A temporary anode groundbed can be constructed from lengths of rebar / sections of old pipe that

are connected to one another via welded bolts and an interconnecting cable.

This temporary groundbed should ideally be placed in a stream or canal near the CP current injection

point. If necessary the groundbed can be shallow buried, but this will limit the output of the

groundbed and therefore in turn the DCVG survey signal.

Instead of a TR (for an existing ICCP System) a 12 Volt DC battery can be used. Alternatively a

controllable DC output welding machine can also be utilised (which does not operate "soft start"),

although a power supply e.g. generator would also be required.

A connection to the pipe is still required to complete the CP circuit, this could be at existing test

posts, valves or exposed sections of pipe (thermit welding / pin brazing of new cable connections

must be subject to a preliminary wall thickness measurement).

The interrupter is installed as per the diagrams. The signal strength should be measured at the point

of injection, and the next available point.

If the signal is required to be increased the following options are available;

Install additional 12 Volt DC batteries in series i.e. 24V, 36V, 48V etc.

Increase the DC Output of the welding machine.

Increase the quantity (surface area) of the temporary groundbed materials.

Reposition the temporary anode groundbed to a more remote position from the pipeline.

3.3.2 Overview Diagram

3.3.2.1 Interrupter in TR Positive

28

3.3.2.2 Interrupter in TR Negative

29

4. Appendix 2.1- Bellhole Excavation Full Records

4.1. Bellhole 001

4.1.1 Data Input

Unique Excavation ID: 5525-BH001

Date of Inspection: 25 February 2016

Pipe Construction (Year): 1968

Age: 48 Years

Steel Grade: X52

Classification: Class 1

Operating Pressure: 30 bar

Operating Temperature: < 250 deg F

Pipe Internal Diameter: 1000 mm

Nominal Wall Thickness: 12.00 mm

Depth of Cover: 2.1 m

Latitude: 41° 27' 14.356" N

Longitude: 45° 7' 6.184" E

Elevation: 1006 ft

As Found Site Photo: As Found

Soil Resistivity @ Interface: 465 ohm.cm

pH @ Pipe / Soil Interface: 6.03

Excavated Site Photo: Excavation

Coating Type: Two Layer Tape Wrap

Coating Condition (General): Good

Coating Condition Photo: Coating

Weld Type: Spiral

UT Grid Square Size: 100 mm

Length of Pipe Tested: 1.0 m

Longitudinal Grids: 10 A-J

Circumferential Grids: 32 1-32

UT Grid Photo: UT Grid

Calibration Block Measurements:

1.43 1.5mm

2.46 2.5mm

4.95 5.0mm

9.96 10.0mm

15.07 15.0mm

20.04 20.0mm

30

4.1.2. UT Grid Records

A B C D E F G H I J

1 11.83 11.92 12.03 11.76 11.89 11.88 11.75 X 11.94 11.63

2 12.04 12.19 11.95 11.76 11.87 11.78 11.73 11.68 11.56 11.25

3 11.76 11.76 11.85 12.00 12.02 12.20 11.89 11.74 11.73 10.43

4 12.08 11.76 11.88 X 11.92 X 12.02 11.69 9.39 11.66

5 12.00 12.19 11.62 12.01 11.91 11.64 11.65 10.30 11.74 11.94

6 11.71 11.80 11.92 X 11.89 11.90 12.18 11.74 11.77 11.77

7 11.98 11.86 11.85 11.75 12.08 11.75 11.78 11.85 11.67 11.79

8 11.72 12.17 11.89 12.06 11.90 11.89 11.82 11.72 11.71 11.86

9 11.86 12.12 11.88 11.91 11.96 11.69 11.70 11.65 11.73 11.74

10 11.77 11.87 11.78 11.98 11.78 11.85 11.90 11.83 11.74 11.78

11 12.03 11.97 12.07 11.64 11.88 12.02 11.74 11.73 12.00 11.92

12 11.92 11.94 11.89 11.89 11.96 11.99 11.92 11.79 11.79 12.20

13 11.64 11.76 11.87 11.81 11.81 11.77 11.72 11.73 12.06 11.74

14 12.05 11.98 11.60 11.96 11.74 11.73 11.99 11.92 12.03 12.06

15 11.83 11.68 11.72 11.72 11.78 11.80 12.05 11.89 11.81 11.98

16 11.83 11.79 11.89 11.89 11.75 11.77 11.93 11.86 11.61 11.63

17 11.94 11.92 11.76 11.75 11.78 11.35 11.34 11.11 10.53 11.61

18 11.69 11.78 11.50 12.01 11.72 11.61 11.85 6.50 11.72 11.67

19 11.88 11.81 11.75 11.85 11.85 11.88 11.39 4.35 11.64 11.64

20 11.88 11.81 11.75 11.85 11.85 11.88 11.68 11.78 11.78 11.18

21 11.70 11.76 11.82 11.96 11.60 11.84 11.87 11.91 11.72 11.78

22 11.80 12.01 11.89 12.05 11.78 11.73 11.76 11.74 11.58 11.99

23 11.55 11.91 11.82 12.05 11.60 11.91 11.64 11.58 11.74 11.74

24 11.76 11.65 11.76 11.68 11.68 11.64 9.15 11.59 11.24 11.67

25 11.66 11.82 11.76 11.70 12.05 11.31 11.75 11.69 11.70 11.72

26 11.84 11.84 11.72 11.93 12.00 11.41 11.62 11.29 11.75 11.75

27 11.96 11.76 11.73 11.74 11.80 11.74 11.80 11.78 10.92 11.76

28 11.84 11.67 11.66 11.65 11.77 11.77 11.88 11.69 11.57 11.71

29 12.05 12.05 11.48 11.22 10.56 10.52 11.81 11.74 11.76 11.93

30 11.99 11.92 11.83 11.89 11.98 11.82 12.02 11.81 11.71 11.32

31 12.07 11.83 11.79 12.02 12.02 11.92 12.09 11.85 11.66 11.62

32 12.04 X X 11.74 11.75 12.04 12.05 12.00 11.89 11.70

31

4.1.3. Pitting / Longitudinal Measurements

Grid Positions

Maximum Pit Depth (mm)

Longitudinal Length (mm)

Allowable Length (mm)

Pass / Fail

B30 4 35 145.15 PASS

C30 2 25 496.61 PASS

C29 8 42 68.69 PASS

C29/B29 3 39 215.04 PASS

19H/19I/19J 8.37 82 65.33 FAIL

4.1.4. Google Earth Image

4.1.5. Output Summary Tables

4.1.5.1 GOGC Level 1 Assessment (Remaining Wall Thickness)

GOGC Level 1 Assessment Fail

Minimum UT Grid Measurement 4.35 mm

UT Grid Percentage Wall Loss 63.8%

GOGC Level 1 Assessment Requirement Undertake GOGC Level 2 Assessment

4.1.5.2 GOGC Level 2 Assessment (Pitting / Allowable Longitudinal Length


% Over Allowed Effective Length 25.51%

Pit Depth (@ Worst Case) 8.37 mm

Measured Effective Longitudinal Length 82 mm

Allowable Effective Length 65.33 mm


32

4.1.5.3 GOGC Level 3 Assessment (Maximum Allowable Operating Pressure

GOGC Level 3 Assessment Pass

Operating Pressure 30 bar

Level 2 Worst Case Pit Depth 8.37 mm

Level 2 Worst Case Longitudinal Length 82 mm

Design Pressure 61.95 bar

Safe Operating Pressure 59.44 bar

GOGC Level 3 Assessment Requirement Coating Repair Sufficient for Operating Pressure

4.2. Bellhole 002

4.2.1 Data Input


Date of Inspection: 25 February 2016


Age: 48 Years

Steel Grade: X52







Latitude: 41° 26' 45.459" N

Longitude: 45° 6' 34.712" E

Elevation: 1000.56 ft








Weld Type: Spiral



Longitudinal Grids: 10 A-J



Calibration Block Measurements: 1.53 1.5mm

2.53 2.5mm

5.07 5.0mm

33

10.03 10.0mm

15.08 15.0mm

20.06 20.0mm

4.2.2 UT Grid Records

A B C D E F G H I J

1 10.62 10.50 10.68 X 10.45 10.47 10.47 X X X

2 10.69 10.46 10.51 X 10.65 10.50 10.76 10.57 10.66 X

3 11.52 11.08 10.93 X 11.01 10.80 10.93 10.53 11.14 11.15

4 X 10.85 10.87 X 11.00 10.64 11.12 10.85 11.38 10.75

5 10.83 10.91 11.15 11.85 10.97 10.72 10.74 11.40 10.73 10.66

6 10.92 X X 11.98 11.38 11.35 11.05 10.87 11.23 10.90

7 11.07 10.83 11.17 10.74 11.01 9.24 X 10.96 10.82 10.61

8 11.20 10.70 10.55 10.71 10.69 10.56 X 10.73 10.56 10.74

9 10.48 10.98 10.60 10.64 10.67 10.98 X 10.61 10.62 10.67

10 10.93 11.66 10.86 10.54 10.71 10.57 X 10.68 10.56 10.70

11 10.61 10.77 X 10.77 10.59 X X 10.74 X X

12 10.90 10.75 11.00 10.54 X 10.60 11.00 10.58 10.63 10.41

13 10.54 10.52 10.57 10.58 X 10.54 10.50 10.62 10.45 10.75

14 10.61 10.50 10.43 10.70 10.81 10.66 10.52 10.92 10.55 10.47

15 10.49 10.53 10.50 10.42 10.41 10.59 10.53 10.70 10.45 10.41

16 10.33 10.41 10.36 10.35 10.45 10.38 10.49 10.45 10.37 10.43

17 10.33 10.42 X 10.29 10.26 10.25 10.26 10.37 10.34 10.31

18 10.35 10.77 10.42 10.49 10.42 10.45 10.18 10.40 10.30 10.27

19 10.32 10.39 10.75 10.50 10.83 10.42 10.48 10.49 10.80 X

20 10.38 10.46 10.57 X 10.65 10.75 10.40 10.37 10.37 X

21 10.31 10.26 10.51 10.75 10.59 10.56 10.36 10.30 X X

22 10.62 10.30 10.35 10.47 10.49 10.45 10.42 10.32 X 10.42

23 10.32 10.38 10.37 10.54 10.47 10.45 10.47 10.32 10.33 10.39

24 10.33 10.35 10.31 10.33 10.41 10.38 10.44 10.30 10.33 10.44

25 10.34 10.37 10.33 10.31 10.45 10.49 10.47 X 10.53 10.35

26 10.33 10.21 10.31 10.35 10.41 10.41 10.32 10.41 10.30 10.31

27 10.37 10.41 10.40 10.35 10.34 10.27 10.45 10.40 10.22 10.90

28 10.82 10.48 10.48 10.43 10.42 10.45 10.49 X X 10.57

29 10.36 10.42 10.45 10.35 10.40 10.67 X 10.43 10.54 10.34

30 10.93 10.63 10.46 10.93 11.21 10.79 11.02 11.41 11.09 11.09

31 11.25 11.37 11.04 11.00 11.27 11.54 11.51 11.34 11.27 11.10

32 10.87 11.01 11.04 11.21 11.12 10.55 10.61 11.32 10.53 11.22


No external pitting present.

34








4.2.52 GOGC Level 2 Assessment (Pitting / Allowable Longitudinal Length






GOGC Level 2 Assessment Requirement Carry out Coating Repair

35

4.3. Bellhole 003

4.3.1 Data Input


Latitude: 41° 26' 34.009" N

Longitude: 45° 6' 45.780" E




Coating Type: Single Layer Tape Wrap


Weld Type: Longitudinal (Seam)

Length of Pipe Tested: N/A (see Note)

Note: Two leaks were identified when the coating was removed. The areas of corrosion were

associated with the minimal overwrap on the original coating (50mm of 900mm width tape).

A coating repair was undertaken such that no further corrosion would occur at the existing leaks (i.e.

the holes would not increase in size), and sufficient reinforcement was made to ensure the repair

remains in place but it was made clear to all personnel that this does not constitute a repair of the

leak.

4.4. Bellhole 004

4.4.1. Data Input


Date of Inspection: 01 March 2016


Age: 48 Years

Steel Grade: X52







Latitude: 41° 24' 52.57" N

Longitude: 45° 7' 32.42" E







36

Coating Condition (General): Fair





Longitudinal Grids: 5 A-E




1.78 1.5mm

2.8 2.5mm

5.31 5.0mm

10.33 10.0mm

15.39 15.0mm

20.32 20.0mm


A B C D E

1 11.99 11.94 12.46 12.53 12.01

2 12.25 12.11 12.13 12.16 12.13

3 12.12 12.09 12.15 12.06 12.05

4 11.97 12.07 12.02 12.04 12.09

5 12.37 12.12 12.12 12.15 12.17

6 12.18 12.20 12.12 12.14 12.05

7 12.18 12.24 12.37 12.33 12.50

8 12.58 12.31 12.22 12.51 12.49

9 12.43 12.26 12.41 12.23 12.35

10 12.73 12.44 12.21 12.19 12.19

11 12.27 12.36 12.23 12.24 12.18

12 12.16 12.44 12.33 12.44 12.11

13 12.17 12.66 12.55 12.61 12.42

14 12.21 12.38 11.99 12.07 12.11

15 12.97 12.77 12.38 12.12 11.99

16 12.82 X X 12.33 12.30

17 X X X X X

18 X X X X X

19 X X X X X

20 11.93 11.84 11.53 11.88 11.49

21 11.48 11.70 11.52 11.64 11.72

22 11.54 11.78 11.69 11.58 11.51

23 11.49 11.66 11.91 11.41 11.46

24 11.33 11.38 11.38 11.44 11.50

25 11.44 11.49 11.28 11.33 11.25

37

26 11.46 12.13 11.42 11.36 12.30

27 11.37 11.39 11.37 11.34 11.39

28 11.35 11.44 11.43 11.56 11.47

29 11.31 11.29 11.29 11.86 11.92

30 11.37 11.41 11.40 11.45 11.68

31 11.32 11.38 11.33 11.35 11.30

32 11.39 11.45 11.34 11.42 11.38


Grid Positions

Maximum Pit Depth (mm)

Longitudinal Length (mm)

Allowable Length (mm)

Pass / Fail

ROW 15 0.5 280 INVALID PIT DEPTH N/A

ROW 16 3 85.5 215.04 PASS


4.4.5. Output Summary Table





GOGC Level 1 Assessment Requirement Carry out Coating Re-pair

38

4.5. Bellhole 005

4.5.1. Data Input


Date of Inspection: 23 March 2016


Age: 48 Years

Steel Grade: X52







Latitude: 41° 24' 27.11" N

Longitude: 45° 6' 52.26" E

Elevation: 1121 ft








Weld Type: Spiral



Longitudinal Grids: 5 A-E




1.54 1.5mm

2.53 2.5mm

5.01 5.0mm

10.06 10.0mm

15.11 15.0mm

20.07 20.0mm

39


A B C D E

1 10.41 10.46 10.58 10.61 10.61

2 10.57 10.68 10.70 10.67 10.56

3 10.36 10.62 10.58 10.61 10.66

4 10.58 10.64 10.64 10.69 10.58

5 10.58 10.63 10.59 10.58 10.58

6 10.60 10.68 10.66 10.54 10.64

7 10.61 10.64 10.62 10.56 10.61

8 10.61 10.61 10.62 10.61 10.59

9 10.61 10.57 10.62 10.62 10.61

10 10.61 10.64 10.67 10.61 10.63

11 10.66 10.66 10.69 10.62 10.65

12 10.70 10.64 10.69 10.74 10.67

13 10.62 10.74 10.71 10.76 10.63

14 10.71 10.76 10.64 10.66 10.56

15 10.50 10.56 10.60 10.68 10.59

16 10.57 10.58 10.53 10.51 10.61

17 10.54 10.46 10.50 10.51 10.43

18 10.42 10.49 10.54 10.59 10.44

19 10.66 10.49 10.61 10.37 10.46

20 10.60 10.64 10.70 10.46 10.42

21 10.59 10.66 10.66 10.63 10.50

22 10.75 10.63 10.41 10.41 10.45

23 10.65 10.45 10.42 10.41 10.43

24 10.65 10.43 10.47 10.49 10.62

25 10.78 10.51 10.49 10.56 10.54

26 10.48 10.48 10.56 10.52 10.39

27 10.42 10.49 10.55 10.49 10.50

28 10.50 10.49 10.51 10.49 10.56

29 10.47 10.50 10.58 10.50 10.51

30 10.54 10.50 10.58 10.50 10.51

31 10.49 10.54 10.53 10.54 10.51

32 10.57 10.53 10.54 10.53 10.51


None.

40








4.5.52 GOGC Level 2 Assessment (Pitting / Allowable Longitudinal Length)






GOGC Level 2 Assessment Requirement Carry out Coating Repair

41

4.6. Bellhole 006

4.6.1. Data Input


Latitude: 41° 23' 13.23" N

Longitude: 45° 5' 39.74" E




Coating Type: Single Layer Tape Wrap



Length of Pipe Tested: N/A (see Note)

Note: The excavation was continually filling with water and as such further testing was not possible at

this time.

42

Annex 3. Bell Hole Reports

Bell Hole 1

Coating damage is where corrosion can take place

43

Water trapped beneath poorly wrapped pipe can lead to corrosion

44

Pits filled with Stopaq

45

Bell Hole 2

Poor coating – allows water ingress

Coating repair – GOGC crew Test post cable re-installed

Ultrasonic calibration

46

Bell Hole 3

Extensive pit Deep pit

Coating repair As found coating condition

47

Bell Hole 4

As found – exposed pipe

Ultrasonic measurements – GOGC crew

48

Bell Hole 5

As found – poor coating

Soil resistivity measurement

49

Bell Hole 6

As found – poor coating. Full of water.

50

Annex 4. Conceptual Cathodic Protection Design

A site survey is required to prepare a detailed design for the pilot section. This conceptual design is

intended to provide a guide to the requirements.

Summary of cathodic protection requirements

No. Description Quantity Measure Remarks

Pipeline Data

ine Data 1 Pipeline length (unterminated at both ends) 19 km

2 Pipeline external diameter 1 m

3 Pipeline average wall thickness 12 mm

4 Coating type - poorly applied PVC tape Survey March 2016

Data from Bellhole Surveys March 2016

5 Average soil resistivity 8 Ohm.m

6 Highest soil resistivity 17 Ohm.m 7 Lowest soil resistivity 5 Ohm.m

Assumptions

8 Coating breakdown 30 % Assumed

9 Protection current density for bare steel 10 mA/m2 Industry norm.

10 Natural potential of pipe -0.5 Volts Assumed

11 Most negative acceptable potential -1.2 Volts ISO 15589-1

12 Most positive acceptable potential -0.95 Volts ISO 15589-1

13 Steel resistivity 0.21 ^.m Typical value

Calculated values

14 Total pipe surface area 59690 m2

15 Bare surface area 17910 m2 Based on item 8

16 Total protection current required 179 Amperes 17 Current density for entire section 3 mA/m2

18 Required negative potential shift at remote point

-0.45 Volts

19 Protection length in one direction 4.1 km

20 Maximum spacing between transformer- rectifiers

8.2 km

An impressed current cathodic protection system has been selected. The current will be supplied

from three 48 Volt 60 Ampere transformer-rectifier units located at KP2, KP10 and KP18. In this case

KP0 is considered to be the railway line.

Anode groundbeds will be of the shallow horizontal type located approximately 100 m from the

pipeline. The length and depth of the groundbeds will be calculated after the site survey results have

been analysed.

Test stations should be installed at approximately 2 km intervals.

51

Annex 5. Priority Matrix- Example

Kilometre Point Weighting 61.45 85.038 98.138 102.947 110.952 111.844 127.744 129.124 132.999

Soil

Re

s

(oh

m.m

)

<10 6 6 6 6 6 6 6 6 6 6

10-50 4

>50 1

SRB present 5

Wit

hin

10

0m

of

Spe

cifi

ed

loca

tio

n

Railway Crossing 10 10 Foreign Crossing 5 5 5 5 Road / River Crossing 5 5 5

3rd Party Damage 10 Previous Leak Evidence 10

Overhead Power Lines 1 1 1 1 Exposed Pipe 1 1 Excavation within 2km -5 -5 -5 -5 -5 -5 Leak History 10 10

CP Mid Point 4 4 4 4 4 Elevation Low Point 10 10 10 10 10 10 10 10 10

Good Access 8 8 8 8 8 8 8 8 8

Coating Defect >10% 10 10 10 10 10 10

Coating Defect <10% 5 10

Standing Water 10 10 10 10

Weighting 34 40 39 38 31 29 45 33 39

52

Annex 6. Workshop material

The relevant documents (agenda, participant list, presentations, photos, etc) could be found in the ITS web site (please follow the link http://www.inogate.org/projects/72/?lang=en )

Annex 7. Beneficiary appreciation letter

The letter has been uploaded in the ITS web site.

http://www.inogate.org/projects/72/?lang=en

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