Abstracts Switzerland

Abstracts of papers to be presented at E-Conference Zürich Switzerland 2022

Alternating current corrosion of pipelines and the geometrical aspects of the corroded steel surface

Markus Büchler, Hanns-Georg Schöneich, Ashok Vimalanandan,

Based on criteria mentioned in EN ISO 18608 German technical rule DVGW GW 28 B1 (A) (2018) provides algorithms to assess the alternating current corrosion risk of high voltage interfered pipelines. One key element is the geometry of the corroded steel surface in combination with the associated defect in the coating. Because EN ISO 18086 – criteria are based on current densities it can be concluded that corrosion may proceed under the extension (depth, width) of the corroding steel surface while current density decreases. This concept comprises some implications with regard to the geometry of the corroded steel surface that has to be expected depending on (beside the impact of AC-voltage, cp-on-potential and soil resistivity) the size of the coating defect and also on the used type of coating. The paper proposes the relevant mathematical equations and shows the conclusions that can be drawn regarding the depth and width of corrosion pits. The results are discussed against the background of corrosion found on high voltage interfered pipelines.

Depolarisation phenomena in soils: remanence of protection after interruption of cathodic protection.

a) GRTgaz, Research & Innovation Center for Energy (RICE), Villeneuve-la-Garenne, France,
clemence.rogier@grtgaz.com, ahmed.fakhry@grtgaz.com and elisabeth.fleury@grtgaz.com
b) TEREGA, Technical Department, Pau, France, francois.castillon@terega.fr
c) GRDF, Technical Department, Paris, France, laurent.henry@grdf.com
d) GRTgaz, Technical Department, Compiègne, France, david.sellam@grtgaz.com
e) Storengy, Technical Department, Bois-Colombes, France, yves.zannier@storengy.com

Cathodic protection conveys an active protection against corrosion to pipeline steel surface in case of coating defect. Operators can be confronted to cathodic protection interruptions leaving the steel surface exposed to corrosion and without active protection during a certain amount of time. This work studies depolarisation phenomena that occurs after cathodic protection interruption. The term “depolarisation” refers to the pipes returning to its free potential value after cessation of cathodic protection. Here we present a laboratory study in soils which shows that shortly after cathodic protection interruption the free potential value of the metallic steel coupon doesn’t return to initial free potential value. A higher free potential value than before cathodic protection application is measured for a long period of time. This effect can be attributed to the formation of a passivation layer at the metallic surface due to pH increase during cathodic protection application. This passive layer confers a remanence to the protection against corrosion of the metallic surface after cessation of cathodic protection. After a certain amount of time a sudden drop of free potential value is observed. This phenomenon can be attributed to the damage of the passivation layer explaining the end of the remanence of protection and localized corrosion initiation. This study focuses on understanding this depolarization behaviour depending on various parameters: level of cathodic protection, time duration of uninterrupted cathodic protection, composition of the soil media and successive cathodic protection interruptions. The objective is to give insight to pipeline operators as to the safety of cathodic protection interruptions on the network depending on environmental conditions.

Keywords : cathodic protection, depolarisation, pipelines, corrosion

Catching the IR-free potential: an overview of the remaining IR components in Off measurements, and importance of the design for PRE with integrated coupon.

Automa S.r.l. – Via Casine di Paterno, 122/A – 60131 Ancona – Italia

As known, ISO 15589-1 protection criteria refers to IR-Free potentials values to be met by applying CP to limit corrosion rate and at the same time to avoid overprotection: in this respect, according to the type of currents influencing the metallic structure, EN 13509 proposes different measurement techniques for measuring IR Free potential.

Off potential measurements are usually performed, both on pipeline and by means of coupon, to try catching the best approximation for the IR-free potential value: for this reason, a fully understanding of all the components that contribute to the obtained potential measure is of very great importance for making better assessment.

In this paper, an overview of the IR components remaining in Off measurements is shown, in order to give a better understanding of the results obtained while performing a method or another.

Particularly, when performing instant-off measurements on coupon, both the effects of measurement timing and the importance of the design of the permanent reference electrode with coupon used will be shown by means of real field data.

Alkali resistance of coatings? Will tests of cathodic disbondment provide reliable statements to this question?

Thomas Loeffler  

It is generally accepted that the effect of cathodic protection is based on the activation polarization and the concentration polarization of the steel surface resulting in an increase of the pH at the interface between steel and soil. This increase in pH value may affect the adhesion of the corrosion prevention coating in the immediate vicinity. The criterion of cathodic disbondment CD is therefore part of all serious standards for the corrosion protection material of buried or subsea steel pipelines. in conjunction with CP.

Interestingly, the effects of the alkaline environment on corrosion protection materials themselves have not yet been the subject of normative considerations, although possible damage to the coating material by alkali may pose a significant risk to the pipeline.

To close this knowledge gap, experts from various areas of the pipeline industry have developed a quick and easy to perform test under the umbrella of the DVGW.

The first results of this study will be presented in this paper. The results confirm a very different behaviour of the investigated materials, which properties can also differ significantly from the behaviour shown in the established CD test.

Stress Concentration Tomography Linked to Metal Loss on Corroded Pipelines

Ben Clarricoates
Speir Hunter

Stress Concentration Tomography (SCT) has been used to inspect over 1000 kms of operational pipeline globally with 163 Direct Assessment excavations used to verify the Stress Concentration Zones (SCZs) detected. Commonly integrity managers have struggled to fully understand stress information and know how to incorporate it into their management plan. Clearly there is a need to translate stress into a more recognisable quantity. In this paper we use this database to show how SCT stress correlates with the independently measured depth of corrosion and has no apparent relationship with other geometric variables which includes circumferential and axial extent of corrosion. This research offers integrity managers a more tangible and valuable SCT output for inclusion in their management plans.

In-situ spectroscopy measurements on carbon steel under cathodic protection

Federico Martinelli-Orlando, Ueli Angst
ETH Zurich, Zurich, Switzerland

Cathodic protection (CP) is an electrochemical technique used to reduce corrosion rate of carbon steel to negligible values. Despite the worldwide use of this technique for protecting underground structure for almost 100 years, the working mechanism of CP is still under debate. The aim of this work is to verify with in-situ spectroscopy measurements, the formation of a passive film on carbon steel during CP. In this study active reflectance spectroscopy (ARS) and electrochemical impedance spectroscopy (EIS) measurements were used to verify the passive film formation in CP. The increase in absorbance in the UV region and the increase in the polarization resistance (Rp) suggest the formation of passive film on the steel surface under cathodic polarization.

A New Rapid and Non-Intrusive Magnetometry-Based Inspection Method to Address Corrosion Under Insulation Problem

Chau Vo      chau.vo@speirhunter.com

Managing Corrosion Under Insulation (CUI) is one of the key challenges faced by the oil and gas processing industry. CUI is estimated to incur 40-60% of the process plant maintenance costs in the UK. The principal issue is that external coatings and insulation prevent advanced and conventional inspection techniques from detecting the presence of corrosive product build-up on the external pipework surface.
This paper introduces a Magnetometry based inspection method called Focussed Stress Concentration Tomography (FSCT) which is rapid and non-intrusive and has been shown to successfully detect the presence of corrosion without removing the coating or insulation. The results of testing and trials on pipework in both operational and decommissioned plants will be presented along with a description of the probe, methodology and real time notification to the operator where corrosion is detected. The paper will also go on to describe enhancements which are intended to further improve the technique.

Real-time analysis of CP data to detect external damages by construction machinery (PipeMon+)Real-time analysis of CP data to detect external damages by construction machinery (PipeMon+)

Patrick Krzyzak

For a safe long-term operation of pipelines continuous remote monitoring gets more and more important. PipeMon+, an Open Grid Europe development, can detect third-party damages by real-time monitoring of cathodic corrosion protection system. To handle this big amount of data the system uses a cloud-based software which computes the incoming data virtually in real time. In various field tests, practical applications on customers and OGE pipelines and in external benchmark tests PipeMon+ has proven its functionality and performance. Herein the general principle of PipeMon+ and the development of an AI based CP data analysis tool is reported.

The role of HCO3− and iron bacteria in the tubercle formation on ductile iron pipelines in aerobic alkaline soil

Fumio Kajiyama, Dr.
Tokyo Gas Pipeline Co., Ltd., 1-5-20, Kaigan, Minato-ku, Tokyo 105-8527, Japan

The author noted that a natural gas 150 mm diameter ductile iron pipeline corrosion as high as 0,384 mm/y in aerobic alkaline soil containing HCO3− and iron bacteria. The pipeline had been in service of 17 years. The aerobic iron bacteria contain chemolithotrophic autotrophs, which can be considered to obtain energy from the oxidation of Fe(CO3)22− to FeOOH. It is probable that the observed formation of stabilizing hard tubercles is the result of the coexisting opposite charges, that is, positively charged FeOOH and negatively charged H3SiO4− in soil. Thus, tubercles shield the surface of pipes from oxygen, resulting in differential aeration corrosion. Graphitic corrosion occurs at the pit beneath the tubercle.

Cathodic Protection of Above Ground Storage Tank Bottoms – Soil Side

Lessons Learned and what we are doing today
Jeff Didas – Kinder Morgan, Inc.  Tubac, AZ USA
Discussion – Storage Tanks
We have learned a lot of lessons about CP for storage tank bottoms the past 100 years.
This paper will discuss some of those lessons, how we have changed CP designs due to regulatory changes and what we are doing today to provide CP for the soil side of storage tank bottoms.

Microbially influenced corrosion on pipelines: A discussion of the influencing parameters based on the concepts of R. J. Kuhn

Markus Büchler , (SGK Swiss Society for Corrosion Protection)

Kuhn introduced cathodic corrosion protection (CP) for pipelines in 1928, establishing a protection criterion of -0.85 VCSE in relation to the on-potential based on empirical investigations and electrochemical considerations. In the following decades, CP with this on-potential criterion was successfully applied to largely all oil and gas pipelines worldwide. In the 1960s, however, corrosion damage occurred on buried gas pipelines despite compliance with this protection criterion, in which poor bedding and the involvement of sulphate-reducing bacteria in the corrosion process were identified. As a result, the IR-free potential with a limit value of -0.95 VCSE was introduced as a protection criterion for anaerobic soils. Even today, the question often arises with regard to the protection criteria to be applied and the operational assessment of the effectiveness of CP. These aspects are discussed taking into account the current state of knowledge and the mechanisms involved.

Condition assessment of asbestos cement pipes in drinking water distribution systems in Germany

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

In Germany, approximately 7 % (36.000 km) of the drinking water distribution system are made of asbestos cement (AC) pipes. As the average age of these pipes is estimated to be 62 years, the majority of them approaches the end of service life which is assumed to be 70 to 80 years for this kind of pipe. The lack of uniform concepts for testing, surveillance and evaluation of the technical condition of AC pipes led to a research project funded by the DVGW (German Technical and Scientific Association for Gas and Water) and some German water distribution companies which was conducted by IWW. The aim was to close these gaps by data collection, systematic acquisition of material specific characteristics and evaluation of operational experiences as well as by corrosion chemical investigations of AC pipe samples.

Problems with the assessment of interference of high-voltage lines on underground pipelines with very good coatings

Jerzy Sibila, Jerzy Mossakowski, Łukasz Sadowski
Corrstop Co. Ltd. Poland

When evaluating a.c. corrosion of underground pipelines, soil resistivity values and quality of pipelines coatings are of significant importance.
Of course, both the high soil resistivity and the excellent quality of pipeline coating significantly reduce the risk of a.c. corrosion. However, excellent coating facilitates the transfer of the a.c. voltage induced in the pipeline, sometimes even for long distances.
However, on the distance of several dozen kilometers away from the intersection of the high-voltage line with the pipeline, the quality of insulation on the pipeline may be significantly worse and the soil resistivity may be low. This is often the case for sections of the pipeline laid in the HDD technology, e.g. under the rivers or lakes.
The article presents the risk of a.c. corrosion for such sections of the pipeline, for which bentonite with resitivity of 2-3 Ωm was used to facilitate pulling of the pipes.
In such situations, in places of coating defects, even a low induced voltage may cause an outflow of a.c current with high density.

Corrosion on domestic installation pipes: Water damage caused by galvanic corrosion currents

by D. Joos (SGK Swiss Society for Corrosion Protection)
M. Büchler (SGK Swiss Society for Corrosion Protection)

In combination with geothermal probes, heating systems are nowadays increasingly used to cool buildings in the summer months. The economic and environmental advantages of this technology are undisputed. However, its successful use requires that the conditions relating to corrosion protection are respected. Otherwise, costly leaks can occur after only a few years of operation. The underlying damage mechanism is driven by galvanic corrosion. While the process responsible for damages is well understood, the sudden occurrence of relevant damages needs further consideration. In the past, the damage caused by external corrosion of domestic installations negligible. However, with the introduction of systems that are used for cooling in the summer months the risk of external corrosion in domestic installations has increased considerably, which is reflected in an accumulation of the corresponding damages. The causes of the damages are explained, particularly critical situations identified, and possible protective measures discussed.

Long-term experiment with an AC corrosion penetration probe

By David Joos, SGK, Zürich, Switzerland

 In relation with the investigations in the research projects on AC corrosion on pipelines, an AC corrosion penetration probe was installed at the SGK laboratory in the fall of the year 2013. The probe was exposed to critical conditions regarding AC corrosion. After only one year, the first penetration level of 1 mm was reached. Although the experiment was continued and the basin was sporadically watered again, further penetrations could never be detected subsequently. The experiment was finally terminated at the beginning of the year 2022. The observations are described and put into context with the present understanding of the mechanism of AC corrosion.

Solving shortcomings in CP surveys of complex pipeline structures

By Christophe Baeté, ELSYCA, Leuven, Belgium

Cathodic protection assessment of complex pipeline systems is often challenging due to the limited access of the pipeline or the congested nature of the system. In particular gas stations, river and high-way crossings, or areas where pipelines require mechanical support to avoid stresses on the asset may require a more advanced approach for assessing the protection level and the need for local cathodic protection systems.
One of the solutions is to perform 3D computational modeling that provides a detailed visual representation of the potential and current distribution around the structure. Survey data collected at soil grade is used to calibrate the model which in turn will provide more insight on the protection level of eventual coating defects and will determine the detection limit of the survey methods.
This paper discusses two case studies where the advanced approach supported the pipeline operator in its decision to implement additional cathodic protection systems.

Remote controlled instant off surveys – technological advancements

By Andreas Junker Olesen (MetriCorr)
Frank Fontenay (MetriCorr)
Lars Vendelbo Nielsen (MetriCorr)

Instant-off survey are used to provide important information about the functionality and operation of cathodic protection of buried pipelines. However, traditional measurement campaigns where the CP system is being switched on/off while technicians are performing field measurements may take a long time (weeks or months) and will not provide information on the continuous evolution of the pipeline instant-off potential or other parameters. This paper presents results from a small- and large-scale test of a remote-controlled GPS time-synchronized remote monitoring system, capable of capturing the instant-off potential at every logger position, when synchronized with a rectifier interrupter unit. Additionally, the loggers have a built-in line-current measurement module, that allows for detection of changes in the CP consumption between logger positions, detailed coating impedance analysis and detection of 3rd party coating damage incidents. The functionality is illustrated through examples.

Condition Assessment of metallic pipes – Experiences and Takeaways of collecting pipe samples over 15 years

By Maxim Juschak and Angelika Becker, IWW- Wasser

 The calculation of the individual remaining lifetime of metallic pipelines is a basic factor in rehabilitation planning.
But which kind of benefit is generated, using these experiences in a statistical analysis of a collection of more than 400 pipe samples?
What are the (sometimes surprising) takeaways considering specific use cases or even whole networks? And how can this knowledge be applied in the context of ongoing developments using methods of non-destructive inspection of pipelines.

Soil corrosivity –
What the standards say and what can be actually measured

By Frank Fontenay (MetriCorr)
Amber Hildebrand (Louisville Gas and Electric, LG&E)
Lars Vendelbo Nielsen (MetriCorr)
Andreas Junker Olesen (MetriCorr)

MetriCorr has deployed several thousand corrosion rate sensors for more than 150 pipeline operators. The sensors correlate corrosion rates with pipe-to-soil DC potential (ON/OFF/IR compensated), Pipe-to-soil AC potential, DC current densities, AC current densities, spread resistance etc. The majority of sensors are connected to the pipelines’ CP systems, but a great deal has been left to corrode freely – without cathodic protection.

Louisville Gas and Electric (LG&E) have conducted soil sampling at sensor position (pipe depth) at more than 150 positions where soil type, texture, grain size distribution, chemical analysis, pH, soil resistivity, buffer capacity, microbial SRB activity etc. has been analyzed This has provided an opportunity to correlate corrosion rates actually measured with aforementioned parameters, thus discussing the applicability of various standards predicting soil corrosivity versus real corrosion rate measurements. The field observations are discussed and supported by simple laboratory observations.

Over-Polarization and possible effects on buried pipelines(update)

Lucio Di Biase, Scientific Consultant (Past President of CEOCOR 2009 – 2015) – Italy lucio.dibiase@alice.it
Michael D. Fumei, Project Manager IMOGIS – 28, Rue Diderot 92000 Nanterre – France michael.fumei@gmail.com

Over-polarization on buried pipelines may occur when CP Currents are too high. The effect of over-polarization on the metal of the pipelines depends on their coating, soil conditions and relevant characteristics. The most known effect of over-polarization is “coating disbonding”. Another phenomenon often referred to is the “hydrogen embrittlement” of the steel. Recently some theoretical scientists are trying to consider the phenomenon of “over-polarization” as the main responsible of very catastrophic effects on buried pipelines. Our experience on gas and oil transport pipelines buried since more than 50 years in the real field, on the contrary, demonstrates that the effect of “over-polarization”, while is in practice sometimes unavoidable, on the contrary, it has never been a real concern for pipeline safety/integrity. In countries where the Railways are fed by DC, the interference in the negative section can increase the pipeline On-Potential up to -30 Volt. The Drainages which are installed in the positive position of the section of the interfered pipeline, deliver currents up to more than 30 A, which is the maximum drained value admitted by law, according to the Italian Ministerial Decree edited in 2014.
Only in some specific oil pipelines laid in the 50-60ies, containing some spots of hardened steel (factory defects) in correspondence of some coating fault, some cracks occurred having as a consequence catastrophic oil pollution. Nevertheless, this has been a rare phenomenon. In order to reduce D.C. Interferences on Pipelines, it is technically necessary to install insulating joints thus shortening the parallel routing between Pipelines and Railways. Where the transported fluid is conductive (e.g. Oil or Water Pipelines), particular attention must be paid as the internal part of the pipe may be subject to corrosion due to electrical interference between the sides of the insulating joint. 

EN 50122-2: Provisions against the effects of stray currents caused by DC traction systems

Ulrich BETTE IfB Wuppertal – ulrich.bette@ifb-wuppertal.de

TC 9X/SC 9XC/WG 01 hat die Normenreihe EN 50122 überarbeitet. Die Schlussentwürfe wurden akzeptiert und werden im Laufe dieses Jahres veröffentlicht. In Bezug auf EN 50122-2 wurden im Wesentlichen folgende Änderungen vorgenommen:
– Harmonisierung mit prEN 50122-1:2022;
– Verweise von EN 50162 wurden geändert zu EN ISO 21857:2021;
– Verbesserung von Messmethoden in Anhang A;
– neuer Anhang D „Laborprüfung von Materialien für die Isolation von Schienen”
In dieser Präsentation wird auf einige dieser Änderungen aber auch auf weitere Ergänzungen eingegangen. Hierzu gehören die Empfehlungen bei oberirdischen Strecken keine geringeren Ableitungsbeläge als 0,5 S/km zu fordern und auf Streustromsammelmatten zu verzichten. Weiterhin wurde das Messverfahren zur Ermittlung örtlicher Ableitungsbeläge vereinfacht.

TC 9X/SC 9XC/WG 01 has revised the EN 50122 series of standards. The final drafts have been accepted and will be published later this year. With respect to EN 50122-2:2010, the following significant technical changes were made:
– harmonization with prEN 50122-1:2022;
– references from EN 50162 have been changed to EN ISO 21857:2021;
– improvement of measurement methods in Annex A;
– new Appendix D “Laboratory testing of materials for the insulation of rails”.
This presentation will address some of these changes as well as other additions. This includes the recommendations not to require a conductance per length of less than 0.5 S/km for at-grade sections and not to use stray current collecting mats. Furthermore, the measurement method for assessing the local conductance per length has been simplified.

Pasing the Baton

Vanessa Sealy-Fisher PrSciNat. M.Sc.FCorrISA
Director-Isinyithi Cathodic Protection
Neil C Webb C.Eng. C.Sci. B.Sc.Eng. F.I.Corr
Nace corrosion specialist
Technical Director -Isinyithi Cathodic Protection


The classic image evoked by the term “Passing the Baton” is that of well-toned runners smoothly passing the baton in a relay race. A successful handover is key to winning the race.

This analogy has long been used in the business world – the concept of a smooth transition in leadership requiring a thorough and effective handover, is not unknown to anyone.

So how does this analogy apply to the world of corrosion?
Should this analogy be used in the world of corrosion?

Are the fears of lost corporate memory and lost expertise valid?
How can we “plug the holes” and “mind the gap” to ensure that past mistakes are not repeated.
How can we stop ourselves from re-inventing the wheel?

This paper will examine the handover of corrosion experience and expertise between generations. Through discussion and investigation, we will explore some avenues through which those of us with grey hair can ensure that our scars were not earned in vain and seek to find ways that others can benefit without being scarred as badly in the process.