CED Working Day and Symposium on Atmospheric Corrosion in Industrial Applications
The tenth CED Working Day was held on Tuesday 24 April 2018 at The Centre, Birchwood Park, Warrington. Some thirty-nine delegates were welcomed by Chairman, Nick Smart. In addition, there were several exhibition stands, a visit to Wood plc test facilities, and CED Working Group Meetings.
Professor Stuart Lyon (University of Manchester) gave an introductory lecture entitled, ‘Introduction to atmospheric corrosion – mechanisms etc’. Given the large surface areas of materials exposed to the atmosphere, annual losses due to corrosion in the UK are in the order of several hundred million pounds. The atmosphere is one of the most common natural environments to which materials are exposed, however unlike most environments, the atmosphere does not provide constant exposure conditions. Thus, the corrosion rates of similar specimens exposed to the atmosphere have poor reproducibility. The main constituents of the atmosphere are essentially constant, however minor components can affect corrosion rates significantly, for example, the concentration of water vapour can vary over a large range. Three primary sources of air pollution are, volcanic action, vegetation and animal wastes, however sea-spray and dust from the earth also need to be considered. Pollutants are also classified as gaseous, particulate or aqueous (dissolved in rain) and man-made atmospheric pollution includes that from burning fossil fuels, chemical processing, sewage treatment and farming. Stuart went on the explain climate effects, macroclimates and microclimates, and that ISO 9223 provides a classification scheme for ranking pollution in a particular climatic location, which is based on the deposition rates of SO2 and Cl-. Atmospheric corrosion only proceeds when sufficient water is present to solvate ions generated during anodic and cathodic reactions. By definition, at 100% Relative Humidity (RH) condensation occurs. Metal corrosion cannot occur unless there is sufficient liquid water on the surface. The time during which RH exceeds a critical value is defined as the ‘Time of Wetness’ (TOW) and ISO 9223 also includes a scheme for ranking a particular climate in terms of TOW (hrs/year). The standard also provides a classification scheme for the ‘Corrosivity’ of an environment, based on the expected annual corrosion rate over 1 year. Finally, specific mechanisms relating to the atmospheric corrosion of iron and zinc were outlined.
Richard Bewell (Engineering Manager, BAM Nuttall) gave a presentation on, ‘Atmospheric corrosion prevention in the windpower industry’. The ‘Blyth Demonstrator Project’ (located about 5.6 km off the North-East coast of England at a water depth of about 38m) has five 8.3 MW turbines, capable of supplying power to 34,000 homes, with a design life of 26 years, and commercial operations commenced in October 2017. The design is essentially a monopole with a heavy reinforced concrete base approx. 30m diameter x 1.1m deep and using over 1,800m3 of concrete with over 500 tonnes of steel reinforcement per foundation. The towers comprised steel shafts, 60m high x 7.5m diameter with a wall thickness of 70mm. For protection in the splash zone and for atmospheric exposure, Norsok C5M specification was applied.
Cristano Padovani (Wood plc) addressed, ‘Modelling the corrosion behaviour of intermediate level radioactive waste (ILW) containers during prolonged exposure to atmospheric conditions’. The stages involved in waste management are, immobilise and containerise, interim storage, transport to an underground geological disposal facility (GDF) and utilise man-made and natural barriers to prevent/minimise release. The atmospheric corrosion of the stainless steel containers, used for medium- and long-term storage , is induced by chloride-containing aerosols, generated by hygroscopic chloride salts on surfaces. Temperature and relative humidity (RH) determine electrolyte characteristics (e.g. concentration) and hence, corrosivity. The factors investigated were, environmental and corrosion monitoring, pit initiation, and mechanistic and SCC initiation studies. Temperature and humidity fluctuate daily and have seasonal variation for above-ground facilities, but are typically more stable underground. It was found that MgCl2 and CaCl2 were inherently much more corrosive than NaCl (especially with regard to SCC), and that high enough RH can lead to dilution of corrosive ions and prevent initiation or cessation, and that SCC initiation was severely inhibited by induced surface compressive stresses. Mechanistic studies in bulk solution indicated that, under polarization, follow kinetics such as, D = A tn, where D=pit depth, A= a constant, t= time and n is an exponent. Furthermore, it was found that SCC propagated very fast after an ‘apparent’ incubation period. A Parametric model – Atmospheric Corrosion of stainless Steel in Stores (ACSIS) was developed, comprising three basic modules, environmental (is the surface wet ?), corrosion initiation (does corrosion initiate ?), and corrosion propation (if so, how much damage results ?). The Laycock-White-Krouse (LWK) mechanistic model was described and used to relate pit depth as a function of time for high RH’s and different chloride surface concentrations.
‘Assessment of corrosion under insulation and engineered composite wraps using pulsed Eddy-current techniques’ was described by Bill Brown (TRAC Oil and Gas Ltd). This presentation touched on the NDT aspect of atmospheric corrosion. Corrosion under insulation (CUI) is possibly the greatest unresolved asset integrity problem in industry. Current methods for measuring wall thickness under insulation, without removing it, all have severe limitations. In total, there are three eddy current devices available for this. However, TRAC evaluated the recently-introduced ‘Lyft’ – a high-performance reinvented pulsed eddy current (PEC) technique) and also Maxwell produced PEC equipment. Although radiography may also be used, it is generally limited to 6 in. diameter pipework, and computer-aided tomography has also been used. A combined PEC and digital radiography technique was developed by Shell in the early 1990’s. A simplified working model of PEC was described and that the concepts of footprint and average area of a probe are key to understanding what a PEC can and cannot detect. The footprint is affected by the size of the probe and the distance from the component or structure being examined from the probe. The footprint is of utmost importance, as it is the decisive factor in determining the dimension of the inspection grid, edge effect and the smallest volume or defect. Nine case histories using this technique were then given.
Professor Geraint Williams (Swansea University) addressed, ‘Preventing corrosion of galvanized steel in the non-chromate age’. The EU has set a ‘sunset’ date of 2019 for the replacement of hexavalent chromium corrosion inhibitor. The problem of how the performance of new inhibitor pigments could be quantified under atmospheric corrosion was raised. Methods included, external weathering, accelerated salt spray and EIS (immersion in corrosive solutions). Assessment of organic coatings carried out at Swansea University included the use of a Scanning Kelvin Probe (SKP). This involves the use of a reference electrode in a test chamber, without physical contact – i.e. not in a ‘bulk’ electrolyte, providing a ‘spatial map’ of corrosion potentials. Ion exchange materials are promising chromium-free anti-corrosion pigments, in which ‘smart release’ inhibitors are only released whenever a corrosive environment is encountered. ‘Hydrotalcite’ is a layered double hydroxide of general formula Mg6Al2CO3(OH)16.4H2O. The carbonate anions that lie between the structured layers are weakly bound giving the material anion exchange capabilities. Inhibition arises by the sequestered aggressive Cl- ions being exchanged for less aggressive ions. The action of this ion exchange mechanism was studied on hot-dip galvanized steel by SKP. The use of benzothiazole inhibitors as a non-chromate alternative was also mentioned. The mechanism is to stifle the underfilm oxygen reduction reaction. Finally, the next generation of Zn-MgAl alloys for galvanizing was introduced. These are very heterogeneous, comprising a three phase material.
John Broomfield receiving the Paul McIntyre Award from Sarah Vasey.
The second annual Paul McIntyre Award was presented at the meeting to John Broomfield, by Sarah Vasey, President of The Institute of Corrosion. This Award is presented to a senior corrosion engineer, over the age of 30, who as well as being a leading practitioner in his field, has advanced European collaboration and international standards development (in keeping with Paul’s area of interest). Recipients must have established an international reputation in the field of corrosion engineering. John had originally a background in spectroscopy and applied these studies to monolayers on steel surfaces. Later, he worked on problems with PWR reactors in the UK, later transferring to Taylor Woodrow and subsequently carried out work on concrete pre-stressed pressure vessels. Some very interesting slides on the pioneering work he was involved with were shown.
At the close, Nick Smart thanked the speakers, the delegates for attending the working day, Wood plc staff for the conducted tours of facilities, and the exhibitors, for a successful and enjoyable event.
Editor’s note: Text copyright: David Nuttall, released under CC-BY-NC.
The branch held their AGM at the evening meeting on 11th April 2018, which was hosted by Amey at their International Design Centre in Birmingham.
The outgoing branch Chairman, Trevor Box, thanked the members for their continued support, those that had taken the time to prepare talks and presentations over the previous year and thanked the organisations, companies and individuals that had offered sponsorship, either by way of providing the meeting venues or refreshments at these. The committee members were elected and the new Chairman was Bill Whittaker
Following the AGM, a trinity of experts in galvanic anode technology for use in reinforced concrete gave presentations on developments in the industry, starting with Roberto Giorgini, consultant to Mapei, who had kindly travelled from Holland for the evening. Roberto’s presentation looked at design criteria and reviewed the basis of design for the use of galvanic anodes in concrete, and compared this with the more conventional design processes used for galvanic anodes in other electrolytes. It was noted that agreed design procedures for galvanic anodes in concrete are not documented and reliance on data from the manufacturers is required.
Gareth Glass, from Concrete Preservation Technologies (CPT), presented “Polarisation and Responsive Behaviour of Galvanic Anodes”. This covered the basis for galvanic and hybrid protection technology, the use of potential mapping and potential changes in the early age assessment of galvanic systems, the responsive behaviour of galvanic systems to environmental changes, the importance of responsive behaviour in aged systems and the use of corrosion rates in the assessment of protected structures. Gareth explained that a simple method of checking system installation was to measure two potentials at and away from a sample of the installed anodes, and potential mapping to show early age changes in steel potential was presented. Data were also presented that indicated the current output of aged systems may fall to low levels in dry or sheltered environments and that re-activation occurs when such systems get wet, including in systems older than 10 years. It was further shown that data can be analysed and translated into corrosion rates in the assessment of the structure. Recommendations included the production of brief commissioning reports, using potential mapping to assess performance, taking into account long term responsive behaviour especially in aged sheltered systems that may dry out, and using corrosion rates to assess the condition of the protected structure.
George Sergi of Vector Corrosion Technologies completed the evening’s talks with a presentation on a new dual-phase anode system for protection of steel reinforcement that he had been instrumental in developing with Vector. George described the process by which application of
an impressed current charge can increase the pH around the reinforcement and passivate the steel where corrosion is taking place, and presented some data on the extent
of charge required to do this based on laboratory experiments. The presentation explained how the Vector product could provide a charge phase without an external dc power supply.
After the presentations a lively panel discussion was held with the three experts responding to the audience questions. The Chairman thanked all presenters for the time taken in preparing and attending the very informative meeting.
The last presentation of the 17/18 season was a joint meeting with NACE UK, and Francois Lirola of Saipem, gave a very interesting talk entitled, “Fusion Bonded Joint: an innovative technology for cost effective plastic pipe installed in J&S lay”.
In deepwater, corrosion protection of flowlines is becoming a major issue. Conventional corrosion allowance of carbon steel flowlines, or cladding, leads to excessive procurement costs, installation weight, welding and NDT challenges. Francois introduced an interesting alternative to achieve an acceptable corrosion protection – is the use of plastic liners. However, plastic lining has been mostly limited up to now to reel lay. SAIPEM has developed and patented an innovative and cost effective field-joint system, the Fusion Bonded Joint (FBJ), which can maintain the corrosion barrier across girth weld locations along the flowline. It has minimal impact on the offshore laying rate and it is based on field proven technologies and methods that are commonly employed in gas transportation networks. The design and fabrication of the FBJ system were explained, and the results of the extensive qualification that has been carried out, were shown.
This excellent presentation led to a high level of discussion by the audience, and the chairman thanked Francois for the time taken in preparing this talk and for coming to London to deliver it.
The third branch event of 2018 took place on Tuesday the 27th March, with 32 attendees representing major companies including, Aberdeen Foundries, ABR Engineering, Atkins, Axiom NDT, CAN Offshore Ltd, DNV GL, ICR Integrity Ltd, Lloyds Register, Lux Assure Ltd, Maersk Oil (now TEP UK Ltd), Oceaneering, One Subsea, Plant Integrity Management Ltd, PROSERV, Shell UK Ltd, Sonomatic and Wood plc.
The event was an industrial visit to the premises of Element Materials Technology in Aberdeen, to attend a technical presentation of “Sour Service Testing of Carbon Steel Girth Welds” by Phil Dent, Element’s Global Corrosion Specialist, followed by a visit to the new H2S / Sour Service Laboratories.
Phil Dent, Element’s Global Corrosion Specialist explains SSC Phenomenon.
Ian Farquharson, General Manager of Element Aberdeen and Edinburgh branches, introduced Element, and noted that is ranked as the 5th biggest materials testing and certification firm in the world following its recent merger with EXOVA. He also mentioned that Element Aberdeen is a UKAS and ISO/IEC 17025 accredited laboratory which offers one of the most comprehensive ranges of metallurgical materials testing and analysis services in the UK.
Phil Dent started his technical presentation by defining sour service conditions, followed by a description of the various types of sour service cracking mechanisms, and the environmental factors affecting the susceptibility of materials under sour service regimes. The sour service cracking mechanisms which were presented included Sulphide Stress Cracking (SSC), Hydrogen Induced Cracking (HIC), Stress Orientated Hydrogen Induced Cracking (SOHIC), and Soft-Zone Cracking (SZC). The various test methods such as the Four Points Bend test (NACE TM0316), C-Ring test (NACE TM0177, Method C), Full Ring test (BS 8701), and Uniaxial tensile test (NACE TM0177, Method A) were also explained.
The corrosion testing laboratory visit was supervised by Paul Roberts, Corrosion and Chemistry Manager, who explained that the corrosion testing services cover a full range of environmental testing simulations, including pipeline corrosion testing for sour and non-sour applications, hydrogen testing, pitting, full ring tests, as well as SCC tests.
Element Laboratories in Aberdeen also specialise in materials qualification for sour service applications and offer standard HIC, SSC tests and also more specialised Full Ring and SOHIC tests and follow international testing standards and protocols such as those from ASTM, IP MIL and NACE. Paul summarised the procedures for the H2S sour service axial tensile test, high temperature / high pressure, electrochemical tests and strain gauging.
Element Laboratory Example of Serious SCC Type Cracking.
The questions raised by attendees during the technical presentation and laboratory visits were well responded to by the hosts. This event attracted a high interest within the professionals and executives of major oil and gas operators, engineering consultancies, and service companies in Aberdeen, to visit one of the major testing and materials qualifications bodies here in United Kingdom. Overall, it proved to be an excellent event in every respect.
The April evening meeting had 78 attendees, and followed on from a very successful visit to Aberdeen by the Marine Corrosion Forum.
George Gair – Global Inspection Manager for Subsea 7 presenting to ICorr ABZ.
George Gair of Subsea 7, started the evening session with a thought provoking theme ‘Subsea Inspection – The Future’, that considered many aspects of the current cost reduction environment where there is a major focus now on how to reduce costs by incorporating new philosophies / technologies.
Very clearly the drive is to produce new and robust methods of harvesting sensor data, and subsea hardware suppliers are looking at increased in-situ equipment monitoring and intervention methods (the oceanographic community has developed remote seabed environmental monitoring systems). George highlighted many significant indicators that show a definite trend towards smarter systems, a key driver being to learn and incorporate inspection technologies from other industries such as Aerospace, Automotive, Medical and Power Generation, together with more efficient use of gathered data.
Monzar Najami – Principal Inspection Engineer of Oceaneering International.
Monzar Najami and Hooman Takhtechian of Oceaneering International followed on with a similarly stimulating discussion on the theme of, ‘Integrity Management of Brownfield Projects: Challenges and Rewards’, highlighting the many important analysis and data gathering areas of modern RBI – Risk Based Inspection methodologies.
The presenters informed the audience that the greatest challenge to developing and implementing an asset integrity programme during Brownfield development projects, is the fact that project schedule and milestones often take primacy over integrity management processes, and in particular emerging vital integrity related interventions which can lead to conflict and disagreement. Any delay in the implementation of these activities impedes the Integrity Management Programme (IMP) and increases the level of risk to the facilities in the operating stage.
Key stages in an IMP project were highlighted as:
Identify stakeholders early in the project (project team, operations, planners, site personnel)
Define strategies and processes and add activities to the construction plan (integrated project activity approach)
Analyse historical data (collect the available list of failures, anomalies and review root cause analysis)
Material fitness for new process (review threats assessment and existing material suitability)
Baseline inspections: Get in early (define scope and input your inspection requirements in the manufacturer’s ITP)
Brownfield revamp activities: Scrutinize output (repair recommendations were challenged and resulted in major cost saving, and change in material selection)
Tagging and RBA output alignment with the existing CMMS (understand the existing Computerized Maintenance Management System prior to your RBA to avoid major re-work)
Deployment of new and advanced inspection technologies (to achieve major cost savings)
A wide range of questions followed the very comprehensive presentation and all the presenters’ slides are available on, https://sites.google.com/site/icorrabz/resource-center.
For information about all forthcoming Aberdeen branch activities, please contact, Dr Yunnan Gao, ICorrABZ@gmail.com. To sign up to the branch mailing list, go to, https://sites.google.com/site/icorrabz/home
ICorr Aberdeen will host its Annual Corrosion Awareness Event on Tuesday 14th August 2018. For further details please contact: Corrosion Awareness Chair, Steve Tate on, email@example.com
The May meeting of the Young Engineers programme was held at the CB&I offices in London on the 16th May. The topic was coatings which was presented by David Mobbs and was warmly received by the enthusiastic audience. The presentation covered the high priority areas of coating including the requirement to qualify products to standards, the standards and what they mean, the testing methods required to achieve this qualification, and also looked at some case histories of coating applications good and bad.
Prior to the presentation the case study for the programme was presented to the delegates by Richard Carroll of Shell, who highlighted the importance of working together in the teams to deliver the required information as detailed in the document. In a change to previous years there will be only one case study for all the teams with each team giving a presentation in a competition to be delivered at the November ICorr London branch meeting.
This year the case study covers a number of areas in which the students are being trained including, materials, coatings, CP, failures, and the management of change. The mentors this year are John Boran, Rob Doggert and Chris Googan, and the teams will meet their mentors in the coming weeks to get started on the case study. A Linkedin page and drop box, have been set up for the teams to help them with this process.
The next meeting on Painting, Fire Protection and Linings will take place on the 29th June again being held at CB&I offices on London.
Again we would like to thank our hosts CB&I especially Sadegh Parvisi for organising the venue, our sponsors BP and our speakers, organising committee and delegates without whom we would not be able to stage this event.
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