PF Thompson Memorial Lecture

P F Thompson Memorial Lecture – 2016

Percival Faraday Thompson (1885-1951) is recognised as Australasia’s pioneer in the science and technology of metallic corrosion and its mitigation. In recognition of this singular distinction the Australasian Corrosion Association inaugurated the P F Thompson Memorial Lecture in 1951. The Lecture is the Association’s premier dedicated Lecture and the Lecturer is encouraged to mark P F Thompson’s distinction by referring to or emulating the academic and technical qualities for which Thompson became known, particularly his prowess with practical demonstration.

Patricia Shaw has been selected to give the 2016 P F Thompson Memorial Lecture.

Patricia Shaw

Research Team Leader, BRANZ, New Zealand

Corrosion of Polymeric Materials
Corrosion is the deterioration of materials by interaction with their environment. The term corrosion is generally used in reference to metals but also applies to the degradation of polymers, concrete and wood. This presentation will explore the causes and effects of corrosion on polymeric materials. It will provide an overview of the environmental factors which may affect polymeric materials, and the impact of those effects on their performance. The challenges of measuring and understanding polymer degradation will be discussed and some practical examples used to illustrate the importance of this field of corrosion.

Patricia Shaw is the Better Buildings Research Team Leader at BRANZ, leading a team of material scientists, fire engineers and structural engineers. The team are currently working on over 20 research projects into improved techniques and materials for use in the building industry. Patricia obtained a PhD in Chemistry from the University of Auckland and has over 20 years’ experience as a Materials Scientist. She previously worked for the NZ Defence Force, specialising in protective coatings and managing their corrosion program. Since joining BRANZ her research focus has been on the resilience and durability of building materials, with a particular interest in the degradation of polymeric materials.

Plenary Lecturers

Howard Combs

General Manager- Global Sales, Carboline, USA

Emerging Technologies for Pipeline coatings – For Directional Drilling
For over 40 years, horizontal directional drilled (HDD) crossings have been used for buried pipelines. During the drilling and installation process the anti-corrosion exterior coatings are subjected to a very high degree of abrasion. This paper talks about the different types of ARO (Abrasion Resistant Overlay) coatings that are used to help protect the pipelines during this process of directional drilling.

Howard Combs has spent the past 38 years in the protective coatings field. He has held senior positions in global companies, being responsible for Sales, Marketing, R&D and Manufacturing. He is a specialist in elastomeric coating technology. Howard graduated with a business degree from Brigham Young University in 1975. Today he is based in the headquarters of Carboline, St Louis USA and heads up the Carboline global sales group.

Nick Laycock

Senior Materials & Corrosion Engineer, Shell, Qatar

Corrosion Control in Wet Gas Pipelines
Wet gas pipelines present multiple challenges for corrosion and integrity engineers. In particular, the presence of CO2 and H2S can create the potential for very high internal corrosion rates and in some cases for Stress Corrosion Cracking. Consequently, there are demanding requirements for pipeline materials, corrosion inhibitors and chemical injection systems. Oil and gas companies use various empirical and mechanistic models to predict the uninhibited corrosion rate for expected service conditions and hence determine their corrosion control strategies. For CO2 corrosion, the various predictive models differ considerably in how they implement the protective effect of surface scales, to the extent that practically significant differences in predicted corrosion rates are often obtained. In sour gas pipelines, there is also a tendency for formation of protective surface scales, but the predictive models are even less well developed. This paper will provide an overview of work carried out in the last decade using various analytical techniques to investigate the structure and composition of the surface scales and how they impact on corrosion in both sweet and sour systems.
Internal corrosion control in wet gas pipelines is primarily achieved by continuous injection of corrosion inhibitor. Many different inhibitor formulations are available in the market and the selection for a particular application is typically based on a programme of qualification testing in the laboratory. Such programmes are intended to ensure that the chosen inhibitor will provide adequate protection to the equipment in all possible environmental conditions that are likely to be experienced during the project lifetime. Since it is not usually practical to test all possible combinations, a selection is often made based on the assumed ‘worst case’ conditions. This paper will discuss some challenges in this approach.
The Pearl asset in Qatar consists of two offshore platforms supplying wet sour gas from the North Field through two subsea pipelines to the onshore Gas-to-Liquids processing plant. This paper will describe the approach taken to the internal corrosion control for these pipelines. Issues addressed will include the chemical selection philosophy, qualification testing protocols, and injection system design. The ongoing integrity assurance process will also be covered, including topics such as corrosion monitoring, cleaning pigging, chemical quality assurance, operating window reviews, and the selection and tracking of appropriate Key Performance Indicators.

Nick is currently the Senior Materials & Corrosion Engineer for the Pearl GTL facilities and the Corrosion R&D Lead for Shell in Qatar. He joined Shell in New Zealand in 2006 and before that he was a researcher and consultant, specialising in localised corrosion. He has authored about 100 peer-reviewed papers and is an Associate Editor of Corrosion Science journal. Nick has an MSc and PhD from the Corrosion & Protection Centre at UMIST, and has received the Shreir Award (1994) and Hoar Award (1997 and 2011) from ICorr, and the Guy Bengough Award (2013) from the Institute of Materials, Minerals & Mining.

Digby Macdonald

Professor in Residence, Departments of Nuclear Engineering & Materials Science and Engineering, University of California, USA

Photo-Electrochemical Impedance Spectroscopic Study of the Passive State
A review is presented of Photo-Electrochemical Impedance Spectroscopy (PEIS), which over the past three decades has developed into a powerful method for investigating the electronic properties of semi-conductors, including the passive films that develop on reactive metals in contact with oxidizing aqueous environments and which have enabled the development of our reactive metals-based civilization. The technique had its genesis in the work of Albery and Bartlett in 1982 and was then extensively developed by Peter starting in the mid-1980s as Intensity-Modulated Photocurrent Spectroscopy (IMPS). The ratio of the vector representation of the incident radiation to the vector representation of the photocurrent, which was an integral part of IMPS, was first demonstrated by Song and Macdonald in 1991 to satisfy the Kramers-Kronig transforms and hence to qualify as a valid impedance within the framework of Linear Systems Theory, thereby validating the use of small signal analysis in interpreting the data. The work of Peter concentrated primarily on characterizing the photo-responses of classical semi-conductors, such as GaAs in sulfide-containing media, which are characterized by relatively small band-gaps, thereby allowing the use of acousto-optic modulators to affect sinusoidal modulation. Macdonald and co-workers explored passive oxide films that are generally characterized by much larger band-gaps. In this case, square-wave modulation produced by a rotating sector light chopper, was employed, with the impedance being acquired using a frequency response analyzer (FRA) that algorithmetrically could accept square-wave modulated inputs. PEIS has proven to be a powerful technique for characterizing the electrical properties of both semi-conductors for solar energy conversion and passive films. In this authors’ opinion, it is the preferred method for exploring the fate of photo-generated electron-hole pairs, which is an issue at the heart of developing more efficient photo-voltaic materials, by quantitatively probing the kinetics of electron-hole recombination. In both the semi-conductor studies and those on passive oxide films, the photo-electrochemical impedance (PEI) is found to be reactive down to very low frequencies (< 0.01 Hz), indicating that the electronic defect structure and dopant defect structure (semi-conductors) or the crystallographic point defect structure (passive films) are strongly coupled, with the relaxation of the latter controlling the relaxation of the former.

Professor Digby Macdonald is currently the Professor in Residence for the Department of Materials Science and Engineering at the University of California at Berkeley. His work involves electrochemistry, thermodynamics, and corrosion science, with emphasis on the growth and breakdown of passive films, chemistry of high temperature aqueous solutions, electro-catalysis, advanced batteries and fuel cells, stress corrosion cracking and corrosion fatigue, materials for nuclear power reactors and the deterministic prediction of localized corrosion damage.  His current research involves studying Simulating Coolant and Corrosion Processes in Water-Cooled Nuclear Reactors and the Development of Deterministic Corrosion Damage Models.  He has published over 900 papers, has 11 patents to his name and still consults with industry on a variety of corrosion related issues.

David Williams

Professor in Electrochemistry, University of Auckland

Advancement of Corrosion Science through New Experimental Methods
Whilst practical studies of corrosion are founded on visual observation, weight-loss measurement and microscopy, and much of corrosion science is still based on the electrochemical techniques originally introduced by U R Evans, these methods are intrinsically limited in the information that they can deliver. Hence there is a constant search for new experimental methods that potentially can lead to new information on the critical chemical events that might drive corrosion processes. Here, I take two examples from my own work.
The introduction of low-noise electrochemical methods to the study of localised corrosion of stainless steels identified the progression from what is now called metastable pitting to a propagating pit. These methods identified the importance of sulphide inclusions and specifically of their size and shape. They did not, however, elucidate the specific chemistry that led to the triggering of the metastable pitting event. New electrochemical microscopy methods identified specific processes at the inclusion edge, that had unusual electrochemistry. New SIMS microscopy then identified a very subtle compositional effect within the inclusions at their edge. The connection between these compositional variations and the observed profound electrochemical effects is however only inferred and has not yet been unambiguously explored. The same low-noise electrochemical methods applied to the study of stress-corrosion cracking of sensitised stainless steels rather elegantly showed cracks jumping one grain boundary facet at a time and interference microscopy identified the initiation event.
Synchrotron X-ray sources have opened up new possibilities for in-situ study of the nucleation and growth of new phases in electrochemical systems since a high-intensity beam of hard X-rays can penetrate a significant thickness of metal and solution without too much scattering. Diffractometry identifies crystalline phases and the high intensity of the synchrotron source means that the development of such phases can be followed from the very first stages of their appearance. Small-angle scattering at grazing incidence detects and measures the appearance of amorphous phases on the nanometre size scale and the use of synchrotron radiation again gives high sensitivity and high time resolution. The combination of these techniques identified the important initial chemistry in the formation of potentially protective crystalline phases – siderite and chukanovite – during carbon dioxide corrosion of steel in hot brine, resulting in a model that broadly explains the significant effects of steel microstructure, alloy composition, solution pH, stirring and of the presence of trace high-valent metal ions in solution. Finally, I shall speculate on the possibilities for mechanistic investigations in corrosion science opened by the new generation of synchrotron and neutron sources and by new in-situ microscopy techniques.

Professor David E Williams is a graduate of the University of Auckland (PhD, electrochemistry, 1974).  After post-doctoral work at Oxford University and Imperial College London and industry experience at IMI Titanium, he developed his research career in electrochemistry and chemical sensors at the UK Atomic Energy Research Establishment, Harwell, in the 1980s. He became Thomas Graham Professor of Chemistry at University College London in 1991 and co-founded Capteur Sensors Ltd. He was Head of the Chemistry Dept. at UCL from 1999-2002 and co-founded Aeroqual Ltd. He was Chief Scientist of Inverness Medical Innovations, based at Unipath Ltd, Bedford, UK, from 2002-2005. He joined the faculty of the Chemistry Dept. at Auckland University in February 2006 and co-founded Air Quality Ltd in 2013. He is a Principal Investigator in the MacDiarmid Institute for Advanced Materials and Nanotechnology.  He is an adjunct Professor at Dublin City University where he was Principal Investigator of the Biomedical Diagnostics Institute and Walton Visiting Fellow of Science Foundation Ireland. He is also a Visiting Professor at University College London and University of Southampton, and has been Honorary Visiting Professor of the Royal Institution of Great Britain, Visiting Professor at University of Toronto and at Cranfield University of Technology. He has published 250 papers in international journals – on electrochemistry, surface science of biomedical devices, semiconducting oxides as gas sensors, air quality instruments and corrosion science – and is inventor of around 40 patents. He is a Fellow of the Royal Society of New Zealand. He has been awarded the John Jeyes medal (chemistry in relation to the environment) and Geoffrey Barker medal (electrochemistry) of the Royal Society of Chemistry, the Pickering medal (technology) of the Royal Society of NZ, the Maurice Wilkins award of the NZ Institute of Chemistry, the U R Evans award of the UK Institute of Corrosion and the Castner medal of the Society for Chemical Industry.