Due to the outbreak of the Coronavirus (COVID-19) around the world, many of the major up-coming events have been cancelled or postponed. These include, CORROSION 2020 (NACE) conference and expo in the USA which is now schedule for June 14-18, 2020. In Europe, Eurocoat in France, PaintExpo in Germany, and Surface World and Surfex in the UK, have all been postponed until later this year.
A Journey into the World of Corrosion Science
The timeline for innovation in corrosion prevention is evolving
Corrosion is a factor within all industries, and left unchecked corrosion has catastrophic effects on infrastructure and transport. With its potential to cause widespread damage across multiple economic sectors, corrosion has spawned an entire sphere of scientific study, innovation, and engineering.
Corrosion science is interdisciplinary in nature, involving organic chemistry, microbiology, electrochemistry, metallurgy, and more. However, it is also a relatively new field, dating back only a few hundred years. In this article, we take a brief look at the history of corrosion science.
Observations of corrosion in history
Throughout the centuries, we can observe actions taken against corrosion. For example, we know that the Romans covered copper utensils with a thin layer of tin to prevent corrosion.
Counterintuitively, there appears to have been little investigation into corrosion until Robert Boyle published two papers which served to introduce corrosion science in 1675. These papers – Of the Mechanical Origin of Corrosiveness and Of the Mechanical Origin of Corrosibility – detailed notes of experiments, mostly undertaken with Robert Hooke between 1654 and 1668 and beyond when Boyle moved to London.
However, despite Boyle introducing corrosion as a science, it wasn’t until the 1830s that the economic consequences of corrosion became apparent. Consequently, in 1837, the British Association for the Advancement of Science offered grants to those studying the action of water and temperature on wrought iron. It was around this time that the potential for profiting from anti-corrosive processes and coatings was first established.
Advances in corrosion protection
Largely because of the financial potential of lengthening the life of corrosive metals, anti-corrosive inventions flowed reasonably quickly in the ensuing years. These included:
- 1837: Galvanisation of puddled iron, invented by H. W. Cranford in England
- 1840: Silver electroplating, invented by George E. Elkington and H. Elkington
- 1869: Nickel electroplating, invented in the United States
- 1878: Hit-dip tinning, patented by Morewood in England
- 1906: Phosphating, invented by T. W. Coslett
- 1923: Anodised aluminium, invented by Guy D. Bengough and J. M. Stuart in England
The rise of corrosion resistant alloys
As well as protecting corrosive metals, corrosion science sought to develop new corrosion-resistant alloys. This branch of corrosion science – the deliberate addition of elements to steel to enhance resistance to corrosion – was pioneered by Michael Faraday in 1819.
Faraday was inspired to find a non-corrosive alloy by the observation that meteorites did not rust. These meteorites contain 8% nickel.
However, Faraday’s main conviction was in the research of electromagnetic induction, and so he did not continue his alloy experimentations. It wasn’t until 1931, when Robert Hadfield was examining Faraday’s notes and experiments, that the scientific community realised that the steel alloy age could have started half a century earlier – if only Faraday had pursued his findings.
The timeline of corrosion-resistant alloys includes these two significant discoveries/inventions:
- 1905: Albert Portevin observed that steels with a chromium content of more than 10% are resistant to attack by common reagents
- 1912-1914: Stainless steels were developed in England and Germany
Electrochemistry, hydrometallurgy, and corrosion science
The electrochemical nature of corrosion is one of the most experimented and discussed aspects of corrosion science. The first record of this theory is found in a paper published by French chemist Louis Jacques Thenard in 1819. Developments after this came as follows:
- 1824: Humphrey Davy first proposed cathodic protection principles.
- 1830: Swiss physicist Auguste de la Rive attributed rapid attack by acid on impure zinc to the electrochemical interaction between the zinc and the impurities.
- 1834: Faraday provided evidence of the connection between chemical action and electrical currents.
- 1907: The function of oxygen as a cathodic stimulator was recognised by Walker, Cederholm and Bent when developing theories of corrosion by neutral liquids.
- 1908: In Germany, Heyn and Bauer found that attack on iron is stimulated by contact with a nobler metal, while contact with a baser metal offered protection against corrosion.
- 1924: Whitman and Russell discovered that corrosion is often intensified when a small anode is connected to a large cathode.
The connection between corrosion and hydrometallurgical processes was first made in the late 1880s, when John Stewart MacArthur discovered the cyanidation process for leaching gold from its ores. However, it wasn’t until many decades later that the process was shown to be an electrochemical one. In 1947, P.F. Thompson demonstrated that by developing a galvanic cell on a gold particle, oxygen on the surface was reduced. This acts as a cathode, while the gold dissolving away acts as an anode. Thus, many hydrometallurgical processes are, in fact, electrochemical processes.
Acid is replaced by oxygen as a main protagonist of corrosion
It wasn’t until the early 1900s that oxygen’s status as a main protagonist of corrosion was established. Until then, it was generally held that acidic conditions were mostly responsible for corrosion of metals. This was specifically assumed in the corrosion of iron, which was assumed to only take place when carbonic acid was present.
In 1905, this false assumption was disproved when it was found that iron exposed to water and oxygen, without the presence of carbon dioxide, was subject to corrosion. Though the presence of acid does accelerate some types of corrosion, it is now understood that water and oxygen are the chief corrosion agents in most natural environments.
This advance in understanding wasn’t entirely revolutionary, however. Many scientists had noted the effect that different concentrations of oxygen have on corrosion. These observations by scientists included:
- 1830: Marianini, in Italy
- 1845: Aldi, in England
- 1889: Warburg, in Germany
- 1908: Kistiaknwosky, in Russia
Further experimentation confirmed that oxygen concentration is an important factor for corrosion scientists to consider. These included experiments by Aston in the United States in 1916, and by U.R. Evans and others in England between 1922 and 1934. U.R. Evans in particular played a key role in establishing contemporary understanding of corrosion processes and is often referred to as ‘the father of corrosion science’. An award in his name is presented annually by the Institute of Corrosion.
As corrosion science improved and developed, it was discovered that covering the anodic or cathodic parts of a metal with certain soluble substances stopped corrosion. These substances came to be called inhibitors. Polish scientist Chyzewski classified these into anodic and cathodic inhibitors.
Much of the experimentation in this area has helped to develop inhibitive paint, mechanically-excluding paints, and zinc-dust coatings. The need for different types of coatings was established by John Samuel Forest in England in 1930.
As with all branches of corrosion science, our understanding of coatings is continually evolving and this is reflected in the continuous development of coating and inspection training.
Corrosion science – a rich history with an exciting future
Like the spectrum of scientific knowledge, corrosion science continues to develop and advance. The brightest and most innovative minds will help all industries to accommodate corrosion in their long-term strategic thinking and everyday plans.
The Institute of Corrosion was specifically set up in May 1959 with the objectives to “disseminate technical information about corrosion matters and to develop by means of social activities, the free interchange of information among members.” Further, the objectives included to “progress towards the establishment and acceptance of suitable qualifications for corrosion engineers, and a promotion of standardization in the terminology and techniques of corrosion control.”
These objectives remain encapsulated in our core values today.
One of the aims of our Young Engineer Programme (YEP) is to ensure that early career members of the Institute of Corrosion benefit from prestigious training initiatives. To learn more about the Young Engineer Programme, visit our YEP pages or email the Institute of Corrosion at firstname.lastname@example.org.
The February meeting was held at Impalloy’s new manufacturing facility in the West Midlands, with Impalloy also sponsoring the food for the event, and Prafull Sharma of CorrosionRADAR, gave a very interesting talk on the monitoring of Corrosion Under Insulation (CUI), Latest Developments and Trends.
Prafull provided with an enlightening presentation into the trends of monitoring CUI and oil and gas inspections in general. Hidden corrosion such as CUI continues to be a big challenge for the asset integrity management of industrial facilities. Industry still spends a huge amount of their maintenance budget on routinely opening up the insulation to inspect the pipes and equipment. There is a growing trend to remotely monitor corrosion in accessible locations using the wireless connectivity and battery powered devices. A new innovative sensor system for monitoring CUI has been developed by CorrosionRADAR. The sensing principle uses Electromagnetic Guided Radar (EMGR), which uses a permanently embedded sensor into the insulation. The data is transmitted wirelessly onto a cloud or on-premises platform and visualization is performed using a remotely accessible dashboard.
The presentation also detailed the latest developments in remote monitoring technology for Corrosion and CUI.
The company have produced a very comprehensive monitoring database utilising 3D models of the plant requiring monitoring. Discussions followed about modification of the system to cover many other aspects of the corrosion dictionary, which Prafull said would be possible! Watch this space!
Following the presentation, a branch meeting was held, with Paul Segers taking on the chair. Detailed discussions followed about future events, membership etc. The branch is looking for new committee members from outside of the CP discipline, in coatings, research, monitoring, etc. If you would like to be involved please contact Paul via via the ICorr office.
The February talk was given by George Winning, Technical Service Manager for Clariant Oil Services in Africa, a Fellow member of ICorr and London branch committee member. George explained in his presentation why the corrosion inhibitor injection systems are required, and reviewed typical systems and corrosion control options, both mechanical and chemical. This was an excellent talk which produced significant discussion amongst those attending.
Within oil and gas operations there is a need to maintain and optimise production through life. One of the most common options to achieve this is the use of water injection to maintain reservoir pressure. With the use of these systems comes issues regarding corrosion as the presence of oxygenated water, scale and microbial growth can lead to premature failure unless efficiently mitigated.
The above corrosion threats were outlined in the presentation, followed by discussion on how the various systems used, amongst seawater, aquifer water, river water and other systems such as PWRI and water and gas (WAG), determine the most suitable mitigation methods.
This led onto the need for the fit-for-purpose design of the system, the maintenance of any mitigation measure and the required monitoring to ensure safe and efficient operation.
This brought up a discussion on many subjects covered. These included microbial monitoring of the system and identification of the most reliable methods, which opened up a philosophical debate on whether any method is truly reliable and led to a conclusion that a number of methods, Serial dilutions, ATP, qPCR or even H2S monitoring should be used in conjunction with trend mapping to ensure the system is running at its optimum level. Other questions revolved around reliability of systems, particularly the deoxygenation system, with the conclusions that effective maintenance and monitoring of the system to identify problems at an early stage are imperative to allow changes to the operation to be made and the system optimised. It was also highlighted that water injection systems are regularly overlooked, as they are not seen as the sales point in oil and gas production, and leaks are not of high environmental concern. This is a mistake as these systems are the most important measure taken to maintain oil production in the secondary oil recovery phase of a project and overlooking these in the short term will affect the economics of the asset in the long term.
The talk was well received being described as ‘Master Class’ and well delivered with clear and relevant arguments made. It was closed with a vote of thanks and a presentation to the speaker.
The branch held its 5th event of the 19/20 season at RGU Aberdeen, with a paper entitled “Structural Integrity Issues: under-deck, air-gap, splash zone assessment / deterioration / repair mechanisms, (for corroded / fatigued conductors, caissons and risers)” by Chris Tierney, SETS. This was a highly successful 1st joint presentation with EI – The Energy Institute, with 75 attendees.
The first part of the presentation considered, conductor integrity, hidden risks and corrosion mitigation, and in the second part Chris discussed new platform-launched technologies for repair of caissons and conductors subsea on ageing assets. After a decade in the subsea engineering sector with Technip, Chevron Upstream Europe, and Pro Dynamic Lifting (PDL), Chris founded SETS in 2011 as a subsea engineering and consultancy specialist. A platform splash zone is an area of multiple risks to production due to the high likelihood of mechanical damage to elements running through this area, cracking and in some geographical locations, very high corrosion rates. SETS provide innovative, engineering and tooling services to deliver efficient conductor management and repair solutions. The company have continued to innovate, learn and produce solutions for this difficult work zone and have been at the forefront of the design and development of technically advanced subsea tooling for conductor cleaning and inspection, clamp repair and shim installation. Unusually, their technology is remotely operated from topside, eliminating the requirement for diver support, and dramatically reducing time and cost. Their success in this area has resulted in the recent acquisition of the company by AquaTerra ( Kintore, Aberdeenshire).
The SETS presentation concentrated on conductors but the technology is equally applicable to caissons and risers. Conductors run from seabed to wellhead, providing environmental protection to the most vulnerable well components. A conductor should be considered a complex system, and its integrity managed accordingly, spanning wells, structural and operational functions. The condition of conductor and guide frames at the spider deck reflect the condition of these at the first elevation subsea. These are the most highly utilised areas in a conductor system, subjected to the greatest environmental loads and generally where majority of defects present themselves. The presentation discussed in detail, marine corrosion, fretting, fatigue, damage mechanisms and progression rates affecting conductors on ageing assets. Chris explained how different marine environments worldwide impact on conductor, caisson and riser integrity and following this, there were many thoughtful questions from the audience.
The February 2020 evening meeting with 55 attendees opened with a discussion of the new ICorr logo and re-branding of the Institute to provide a much needed re-start and more professional focus, with the key being firmly on corrosion prevention by all available means. Following this introduction, there were very informative twin presentations by DNV-GL on risk based inspection activities, covering both PSVs (Pressure Safety Valves) and FPSO’s (Floating Production, Storage and Offloading) units.
The first presentation, by Dr Chris Bell discussed how data analysis of servicing has helped reduce cost and improve safe interval servicing of PSVs. PSVs are installed in process and utility systems to prevent build-up of internal pressure, or external effects such as fire. Over pressurisation of any vessel, or other equipment item, with energy released from the pressurised fluid, or the hazardous or flammable nature of the contents, can have significant consequences on a platform. Valves can block through build-up of wax, gunk or corrosion products within the system and the PSV will fail to lift. For this reason, PSVs are classed as safety critical when protecting hydrocarbon containing equipment and must be safety tested on a regular basis. The testing cannot generally be done in-situ, and valves most usually have to be taken onshore, tested, refurbished and refitted. Typically there are over 100 PSVs on a platform so it is worth optimising the maintenance interval. This can be done by data analysis to find the appropriate time to service the valve based on previous history and ensure a safe practice whilst minimising costs, and the inspection interval can be set so that the residual risk of failure is acceptable.
0.5 billion hours of service data for PSVs have been analysed from 10,311 tests and 544 failures by DNV-GL to allow optimisation of maintenance intervals and manage the inspection of PSVs. A methodology was developed that combined qualitative and quantitative RBI analysis. This multi-layered assessment gained the most information possible from the data, and as an outcome, the average maintenance interval was changed from 37 to 44 months and the test failure rate dropped. So, for an average PSV maintenance cost of £1000, total cost has now reduced by £ 1.1m from £6.5m to £5.4m per year.
The second presentation was by Dr Madhu Parlapalli, who presented a paper on risk based inspection (RBI) of FPSO Cargo Tanks. Risk based inspection in the oil and gas industry of piping, pressure vessels and other critical equipment has been used more recently for planning structural inspections. For floating structures like FPSOs where there are additional requirements to satisfy in the form of Classification Society rules, although risk based approaches are allowed under these rules there are relatively few examples of where this has been applied to plan structural inspections on FPSOs, for items such as cargo or ballast tanks.
It is operationally quite inconvenient to carry out inspections of these tanks on a fixed 5-year interval in line with a standard Class schedule. A risk based inspection schedule has to take account of all relevant degradation mechanisms and the corresponding means of inspection. For FPSO cargo tanks the main degradation threats are fatigue cracking and corrosion / coating degradation and of course general inaccessibility for inspection. The RBI process involves developing a structural hierarchy of ‘accessible’ elements, identifying the relevant ‘failure modes’ and damage mechanisms then evaluating the ‘probability’ ranking for the relevant mechanism. The ‘consequence’ ranking for safety, environment or business impact is then added, and the risk level is evaluated using an agreed risk matrix with the client/owner. An inspection plan can then be developed for different inspection activities to form an optimised inspection schedule. Case studies were presented for ‘hotspots’ identified on an FSPO and RBI analysis used to look at the fatigue degradation mechanism and a coating degradation mechanism. An extensive Q&A followed these 2 excellent papers.
Full details of future branch events can be found on the diary page of this magazine and on the website, or by contacting: ICorrABZ@gmail.com. Copies of the majority of past branch presentations can be found at: https://sites.google.com/site/icorrabz/resource-center, and a photo gallery for all Aberdeen events can be found at: https://sites.google.com/site/icorrabz/event-gallery
A special reminder is drawn to the August 2020 Annual Corrosion Forum (ACF), which unfortunately has now been cancelled owing to the Covid.19 outbreak and knock-on financial effects.