Abstracts Bratislava 2023

Complex Impedance Measurements on a pipeline section to localise corrosion sites

• Lucio Di Biase, Scientific Consultant (Past President CEOCOR 2009 – 2015) – Italy
• Edoardo Proverbio – Full Professor at University of Messina – Italy
• Osvaldo Fumei Technical Director of SOLARIA – Route d’Ajaccio Lieu-dit-Croccichia – 20260 CALVI – France

The measurements of the Complex Impedance on a buried pipeline is an above–ground technique which enables the localisation of corrosions on the steel of a pipeline, even under disbonded coatings. This technique is not simple to be used in the real field as it needs the installation of special equipment to feed an a.c. signal and particularly sophisticated equipment to detect and to record the relevant signal response over the pipeline.
The Complex Impedance Measurements technique over a buried pipeline allows the identification of low/very-low values of the Rp (Polarisation Resistance). This information, together with the D.C. Current requirements and the IR Drop values over a specific section of the pipeline, allows to localise areas where the coating is disbonded, where this disbondment corresponds to corrosions on the steel pipeline or where the coating is missing and corrosion is taking place.
In this paper the results of some tests performed on a real, corroded pipeline are reported. The main limitation of the technique is certainly the fact that, as the portion that can be investigated is in the order of some hundred metres, in order to investigate other sections, the whole installation and equipment (temporary Groundbed, A.C. Feeder, Potentiostat, Galvanostat, Frequency Response Analyser) must be moved along the pipeline, over suspected sections.
Anyhow, it could be of great support in solving doubt cases when the pipeline/coating laying conditions and soil characteristics suggest corrosion likelihood on a specific section of the pipeline.

Degradation of grounding conductors for ac mitigation:
influence of backfill composition and ac current level

Julien Duboscq, Nada Marzouq, Keltouma Zmoug, Ahmed Fakhry, Romuald Bouaffre.

Buried pipelines protected against corrosion by CP systems can be influenced by alternative current flowing from different sources. These influences can lead to important corrosion phenomena. In order to reduce corrosion risk, GRTgaz installs grounding systems such as galvanized steel to mitigate ac effects and discharge induced current in the ground. After a few years, GRTgaz found some grounding conductors with a premature degradation. RICE (Research and Innovation Center for Energy – GRTgaz) has conducted laboratory tests to investigate the impact of ac current level on the degradation of galvanized steel, with different backfill material: sand, bentonite and coke breeze. In the chosen conditions, the higher the ac current, the greater the degradation. The aging of a conductor placed half in sand and half in bentonite or coke breeze does not induce a greater degradation, compared to aging in simple backfill materials (only bentonite or coke breeze). Finally, these tests showed that bentonite allows for a longer protection of steel by zinc, contrary to coke breeze that accelerates the degradation of the conductor.

Julien Duboscq, RICE – GRTgaz  PhD – Corrosion Engineer
julien.duboscq@external.grtgaz.com  

Influence of overprotection on AC corrosion.
Analysis of a real case.

I.MAGNIFICO ivano.magnifico@byautoma.com

Automa S.r.l. – Via Casine di Paterno, 122/A – 6013  Ancona – Italia

 The risk of AC corrosion has always been linked in particular to the parallelisms of underground pipelines with HVAC lines, especially in those geographical areas where the morphology of the territory creates obligatory so-called “technological corridors”, and therefore forces the coexistence of different services over long distances.

More recently, the greater diffusion of AC-powered railway networks has further increased the AC interfering sources, while the use of more performing coatings on underground pipelines has on the one hand increased their insulation from the surrounding soil, and on the other has increased the risk of overprotection compared to old, less performing, or more degraded coatings.

This paper, starting from a real case found in a gas distribution network in a European capital, will present the normative criteria to be used to keep the AC corrosion risk under control, and will highlight how precisely the simultaneous presence of cathodic overprotection may result in an autocatalytic cycle leading to accelerated AC corrosion, in which monitoring becomes essential in order to be able to carry out on time the appropriate corrective actions.

Remote synchronized CP off-potential measurements of test-posts. 

 Paul Mignot

One of the challenges for implementing a remote monitoring strategy for CP is when off-potential measurements are required on the structure. To solve this a remote monitoring solution has been developed that remotely switches the Rectifier and simultaneously identifies the connected test posts and measures the CP at 100ms intervals. In this way the depolarization curve of each test post is recorded. From this curve the off potential value is then automatically identified. The benefit is that a 100% remote monitoring maintenance strategy is now possible when off potentials measurements are required of the structure. This case will be presented in cooperation with DSO Stedin  A secondary use case will be presented where the off potential value is calculated from microvolt measurements along a 30-50m fixed length pipe. This will be presented in cooperation with DSO name to be confirmed 

Stray current corrosion of pipelines: An assessment of critical conditions

David Joos, Markus Büchler and Michael Gerhard
SGK Zurich, Switzerland

The concepts associated with stray current interference are well understood and described in EN ISO 21857. DC interference represents a possible risk for the integrity of buried infrastructure and assessing potentially critical conditions is of highest relevance. In order to understand the limiting influencing factors, laboratory investigations have been performed under extreme soil and interference conditions. These include very low soil resistivity, increased chloride content and anodic current densities of up to 100 A/m². These represent extreme conditions that may indeed be encountered in field applications. The associated results are presented and the possible implications with respect to the integrity of pipelines and mitigation methods are discussed.

Corrosion of steel in soil: A discussion of relevant influencing factors

Markus Büchler
SGK Zurich, Switzerland

Experience shows that corrosion occurs on steel in contact with soil. Without protective measures, such as cathodic corrosion protection, the service life of these installations is often limited and damage cannot usually be ruled out. Nevertheless, numerous infrastructure installations, such as water transport pipelines, low-pressure gas pipelines or penstocks are often buried underground and are operated over extended periods of time. In many cases, the corrosion protection is limited to a coating of comparatively poor quality. The corresponding empirical values regarding the occurrence of damage, the metrological effects as well as the influence of soil parameters and the earthing situation are presented and discussed.

Cathodic protection shielding of buried pipeline coatings

Abdelkader Meroufel, Andrew Gordon, Dominique Thierry
RISE Research Institutes of Sweden

During the 2000s, the concept of cathodic protection (CP) shielding was first raised in open literature and remains debated between coatings professionals. The mechanism of CP shielding, and its understanding continue to be studied for different coatings with different approaches and using various techniques. From the CP shielding factors to the assessment methods, published scientist’s efforts merit a deep analysis to capture the established knowledge and identify the research gaps for complete control of the phenomenon for the reliability of structures. A holistic approach to this topic seems necessary where materials, corrosion, electrochemistry, and transport processes should be considered. In the first part of the present review the recent works related to the understanding of CP were considered to discuss the mechanisms involved underneath coatings. Transport phenomena and their relationship with coating structure are tackled in the second part. Finally, CP shielding assessment methods and modelling works are presented and discussed from different perspectives.

Title: Effects of electrical interference on Microbiologically Influenced Corrosion (MIC)

 S. Jansen, J. Gerritse (Deltares), G.H. Horstink (Gasunie)

Several forms of AC and DC stray currents can lead to interference with cathodic protection, and thus to corrosion. ISO DIS 21857 E:2019 describes criteria for the assessment and monitoring of possible effects of electrical interference, including the practical Q-test. It is unknown whether these criteria are valid for Microbiologically Influenced Corrosion (MIC). This was tested using laboratory experiments with Electrical Resistivity (ER) probes covered with an active MIC biofilm under controlled sulphate-reducing conditions with cathodic protection (-1200 mV vs Cu/CuSO4) in combination with electrical interference. Three exemplary forms of electrical interference were simulated: 1) stray current from a solar park (12 hours interference with +500 mV, 12 hours no interference); 2) interference from passing trains (3 V sinus with a duration and frequency comparable to a representative Dutch railway track); 3) 50 Hz AC interference (1 V and 3 V). The results demonstrate that the timing of interference is important for the effects: in case of 50 Hz interference and interference by trains, no corrosion occurred, whereas in the case of 12 hr interference (simulation of stray current from a solar park), corrosion was stimulated. This might be related to the fact that kinetics is important: for interference, the building up/breaking down of pH gradients is needed, and the increase of microbial activity requires time.

In-situ photometric reflectance measurements of passive film on carbon steel in alkaline electrolyte

Federico Martinelli-Orlando and Ueli Angst
Institute for Building Materials, ETH Zurich, Zurich
fmartine@ethz.ch

The passive film formation on carbon steel has been extensively characterized in the last decades. However, the formation and growth of passive film in presence of cathodic current density, e.g., during application of cathodic protection, is still under debate. The aim of this work is to study the influence of the applied current densities on the passive film formation and growth on carbon steel samples. The formation and growth of the passive film was monitored with in-situ spectroscopy measurements in alkaline electrolyte (pH 13) as a function of the applied potential and as a function of the experimental time. The results showed that the passive film can be formed in presence of both anodic and cathodic current densities. Moreover, the results also showed that the thickness of the passive film increases with the application of less negative potentials and with increasing the experimental time for all the potentiostatic conditions considered. The results obtained in this study are of main interest for cathodic protection conditions of carbon steel in soil.

CP measurements by coupons / Terèga’s feedback

CASTILLON François
francois.castillon@terega.fr

Terega, which operates a 5000 km long gas network in southwest of France, uses permanent coupons on each test point (4000 TP) to assess the CP efficiency, by disconnecting pipe/coupons measurements.
The first coupon was installed in 2003, twenty years later, what is Terega’s feedback on this measurement method ?
Can we detect deposits on the coupon surface ?
Can we evaluate the CP effectiveness with good accuracy ?
What are the disadvantages ?
This presentation is a quick review of the cathodic protection measurements on coupons method and our approach to CP efficiency criteria, cathodic overprotection…

Introducing CMI – a new remote field inspection technique for buried unpiggable pipelines

Mark Glinka
Electromagnetic Pipeline Testing GmbH
Berlin, Germany

For large parts of the buried pipeline network, referred to as unpiggable pipelines, there is no simple and established procedure for assessing the integrity of the pipeline. The Current Magnetometry Inspection (CMI) method detects localised pipe wall anomalies from the ground surface without direct contact with the pipeline. CMI enables the combined assessment of pipeline integrity and coating condition and is simultaneously used to 3D-map pipelines. The condition assessment of the pipe is based on the analysis of the magnetic vortex field generated by an AC-energized ferromagnetic pipe. The underlying physical effects are the skin effect and the magnetic leakage flux.

Effectiveness of cathodic protection under disbonded coatings,
 redefining shielding properties

Dr. Thomas Löffler
DENSO GmbH, Leverkusen, Germany
e-mail: thomas.loeffler@denso-group.com

In the context of cathodic corrosion protection (CP), the shielding effect of delaminated coatings is often discussed. Particularly in the North American countries, the use of non-shielding coating systems is required from the operator for certain pipelines. This is leading more and more to the displacement of coating systems based on polyethylene (PE) and in favour to epoxy based liquid coatings or semi-permeable bitumen tapes with a mesh carrier. In recent years, the debate on shielding or non shielding materials has also been intensified in Central Europe, which is accompanied by the increasing marketing of so called non-shielding products.
This presentation will provide an overview of the shielding/non shielding discussion of pipeline coatings based on current scientific surveys by Dr. Büchler, with taking into account the work of Professor Schwenk and the statements of DIN 30670:2012.
We will try to reverse the discussion from myths and assumptions back to proven scientific facts.

ILI features & ILI verification dig findings –
A Case Study on DESFA pipelines

by N. Kioupis (DESFA S.A., Athens, Greece)

An ILI project is not complete until the reported features have been verified in the field. The process which is followed in the field is important as it helps to a) confirm the reported features providing better knowledge of the condition of the pipeline to the operator and b) confirm the ILI tool performance for use on future inspections.
A case study is presented, by collecting the experience in verification digs and direct inspections on ILI findings of DESFA pipelines.
The investigation on the findings raises various concerns about the choice of appropriate ILI tool, defects assessment methodology and selection criteria of verification digs sites.
The effectiveness of corrosion protection is confirmed by the inspection results, further supported through results of ER probes monitoring and the stricter control on CPS operation and maintenance.

Key words/abbreviations: In Line Inspection (ILI), Cathodic Protection System (CPS)

Best Management Practices To Transfer Knowledge And How They Can Help Young Engineers And Their Companies

Izabela Gajewska, Intertek Production & Integrity Assurance, Manchester, UK

Knowledge transfer (KT) is a challenge that every organisation and industry must face sooner or later. KT is particularly important when more senior and experienced personnel in the business are approaching retirement, when the loss of knowledge can be considerable, with consequential risks to the business. These risks can manifest themselves in several ways, including loss of essential core competencies, safety, business efficiency, business continuity, et al.
KT should equip new, and particularly young, employees with the skills and competencies they need to reach key organisational goals to ensure safe and secure continuity of the business. An effective KT strategy, like any other goal, requires a good plan addressing what knowledge is to be transferred, what the available methods of sharing the knowledge are, and how knowledge acquisition by an employee can be measured. Nevertheless, KT is also about the development of competencies in young engineers and positive engagement, and there is a great importance to personal competency when undertaking engineering tasks.
Whatever work projects these employees undertake, they should be competent to do it. By understanding their limitations, organisations can plan and propose solutions to overcome them. This presentation will provide a guide to creating an effective knowledge transfer process, including some common practical approaches employed in many companies that can help young engineers achieve the greatest output of work while making KT more effective.

Izabela Gajewska is a young engineer with Intertek Production & Integrity Assurance, Manchester, UK, who has been going through a curriculum-based plan to transfer knowledge, including site visit to put theory into practice.
Izabela is an Institute of Corrosion Young Engineer Programme 2020 winner who was presented with a winners certificate at a fully expensed trip to the San Antonio AMPP 2020 Corrosion Conference and Expo.

Influence of changing the water-related corrosion conditions on existing drinking water distribution systems

Timo Jentzsch, Angelika Becker,
IWW Water Centre, Muelheim an der Ruhr, Germany

In times of climate change and water scarcity as well as stricter regulations regarding the water quality, many drinking water supply companies are facing the task to adjust their way of water supply. This includes exploration of new water resources, modification of water treatment processes or blending with additional drinking water from neighbouring supply companies. In most cases, this adjustment of water supply is combined with changes of the water composition and therefore with changes of the water-related corrosion conditions in the existing drinking water distribution system, especially when it contains significant percentages of unprotected iron-based materials. Therefore, it is crucial to evaluate these effects in advance.
This presentation provides an overview of strategic approaches to be applied, from corrosion risk assessment and pipe network structure evaluation to remedial measures such as the use of defined flushing measures or dosing of corrosion inhibitors.

Consumption rate of Zinc Sacrificial Anodes under the combined effects of DC and AC

NEIL C WEBB*
C.Eng. C.Sci. B.Sc.Eng. F.I.Corr. F. & H.L.M.Corr.I.S.A. AMPP Cathodic Protection & Corrosion Specialist
Technical DirectInfluence of changing the water-related corrosion conditions on existing drinking water distribution systems
Timo Jentzsch, Angelika Becker,
IWW Water Centre, Muelheim an der Ruhr, Germany

“The unanswered question is related to the effect of AC grounding on the consumption rate of the zinc anodes. No published literature appears to be available related to the consumption rate of sacrificial anodes under the combined effect of DC and AC.”
This was a conclusion of the paper presented to CEOCOR 2021 on the use of zinc ribbon for integrated Cathodic protection (CP) and AC interference mitigation (ACM)
A further question is hanging on the expected life of zinc ribbon when used in conjunction with de-couplers to provide distributed electrode AC mitigation.
A parallel exposure programme over a period of 9 months has been conducted on field and laboratory samples to provide preliminary indications of the consumption rates of zinc ribbon under the influence of DC, AC and combined DC & AC.
The tests were carried out using controlled voltage sources with a steel counter electrode. As far as was possible, the discharge current was kept constant in order to facilitate the integration of current with time. The samples were removed after 3, 6 and 9 months exposure and weighed to determine mass loss over the exposure period.
The results indicate that contrary to expectations, the superimposition of AC when zinc is used at a sacrificial anode actually decreases the consumption rate of the zinc, thereby increasing its effective electrochemical capacity.

Shining Light on Localised Corrosion

By Alison Davenport

Localised corrosion is controlled by a delicate balance between active dissolution and passive film formation that depends upon local interfacial potential and solution chemistry.  This can be revealed by “watching” corrosion sites grow with high intensity X-rays know as synchrotron “light”. These observations have practical implications for developing strategies to limit and predict localised corrosion.

A practical guide to EN ISO 21857 (Prevention of corrosion on pipeline systems influenced by stray currents).

By Ken Lax

EN ISO 21857 is the first published international standard for the prevention of corrosion on pipeline systems influenced by stray currents. Many stray current issues are difficult for cathodic protection engineers to understand if they do not have a foundation or background in electrical systems and/or physics.
For this reason the standard has a number of worked examples of some of the calculations to help cathodic protection engineers to understand them. Some of the calculations can seem difficult the first time you see them, and this paper and presentation will explain the calculations so that the engineers can prepare their own spreadsheets and be able to check if the results are correct.

Corrosion Rates under Cathodic Protection Conditions.

By Lars Vendelbo Nielsen, Frank Fontenay, Andreas Junker Olesen, MetriCorr ApS.

Every so often we bump into a general question if we can reach a corrosion rate equal to zero under cathodic protection conditions – with or without disturbing electrical interference.
MetriCorr has delivered more than 16.000 ER corrosion rate probes to the pipeline sector and a majority of these are producing data which are transmitted remotely to a cloud hosted data base through where pipeline operators can view and analyze their corrosion rate-, interference-, and cathodic protection data to make sure they are compliant. Despite data gathering is a costly discipline, pipeline operators often generously allow their collected data to be utilized for the benefit of the joint industry in order to sustain better understanding and sound cathodic protection criteria. With this acknowledgment, this paper is intended to provide some statistical figures of corrosion rate versus cathodic protection conditions – with and without the presence of interference. . In addition, it is illustrated how a simple factor plays the predominant role in the corrosivity of the soil.
This study has been based on data from customers that have allowed the incorporation of their data for this statistical purpose.
The presentation is intended in particular as a contribution to the current revision of ISO 15589-1:2015: Petroleum, petrochemical and natural gas industries — Cathodic protection of pipeline systems — Part 1: On-land pipelines.

AC Mitigation System After Ten Years of Operation

Jerzy Sibila, Jerzy Mossakowski, Maciej Mleczko
Corrstop Co. Ltd, ul.Kamienna 87, 62-023 Kamionki, Poland

This case study presents experience from ten years of operation of an AC mitigation system for an underground gas pipeline exposed to the interference of runs parallel overhead 400 kV and 220 kV power lines.
In 2012, thirteen solid state decouplers (SSD) were installed on the gas pipeline and as a result, the measured interfered AC voltage and current densities were reduced to acceptable thresholds. However, since 2012 the load on these three overhead voltage lines has increased significantly and the present measured AC current density at one of the points with the SSD is as much as 595 A/m2. Nevertheless, the measured corrosion rate on the ER probe is only 5,01 um/year.
It seems that the allowable corrosion rate below 10 µm/year is due to the fact that the ON potentials for this pipeline are less negative than -1.2 V (CSE).

Overline pipeline inspection in 5 parallel gas transmission pipelines.

By Peter Soukup, EUSTREAM, Slovak republic

Since 1998, we have been collecting comprehensive data on the effectiveness of cathodic corrosion protection on transmission pipelines. This set of measurements is performed by an external supplier and we call it Overline pipeline inspection. The specialty of our gas transmission pipelines is a system of 4 – 5 parallel transmission pipelines with a total length of approx. 2,300 km, with the length of one gas pipeline line of approx. 460 km. The technical condition of the cathodic protection devices was determined by control measurements, which included also the interference measurements of the currents between own and foreign pipes, investigation of soil aggressiveness and evaluation of the presence and effect of stray currents. In addition to the usual measurements of electrical quantities at the corrosion protection structures, intensive measurements are also performed, where the terrain is traversed step by step in parallel above all pipes at the same time. The most important thing is to identify defects on the insulation, find sections without cathodic protection and accurately measure the depth of the pipeline. The gas pipeline has been traversed 3 times in this way so far. From the measured data, we can compare the impact of corrective measures and also respond flexibly to emergency situations.

Evaluating the Performance of Stress Concentration Tomography for Detecting Defects in Underground Pipelines

by Chau Vo, Bach Vu and Paul Jarram, Speirhunter, Newark, Nottinghamshire, UK

The above-ground inspection technique Stress Concentration Tomography (SCT) aims to identify stress concentration zones (SCZs) in underground pipelines, which may be indicative of defects in the pipelines. This study evaluates the performance of SCT in detecting SCZs using data from SCT surveys and from client-conducted excavation assessments as a “gold standard” for comparison. A binary classification system based on probability of detection (PoD) and probability of false alarm (PoFA) was utilized. Results showed that SCT had a PoD of over 90%, but often came with a high PoFA. The study suggested using predicted stress levels in post-analysis procedure to improve these statistical figures, which was successful in reducing PoFA and could be customized to meet clients’ needs. This is the first investigation into the performance of SCT as an emerging technology based on data collected during excavation, and further improvements will be made with a growing database of verification data.

Slovakia on the Crossroad of the main Gas Routes in Europe

By Richard Kvasnovsky, Slovak Gas and Oil Association, Slovakia

Slovakia has achieved the 167th Anniversary of the gas industry in 2023. Starting with 209 gas lamps in the capital city, Bratislava has become the very important gas crossroad connecting Europe in all directions.
Slovakia has more than 100 bcm/year transmission capacity and with more than 33,000 km of distribution pipelines, it is the second most gasified country in the EU.
Last but not least, its storage capacity represents more than two thirds of the annual gas consumption.
For the future of the Slovak gas industry, it will be necessary to strengthen the production of the renewable gases like hydrogen and biomethane. Several projects have been successfully developed yet.