The second annual Joint Meeting of the Institute of Corrosion, London Branch with the SCI London Group was recently held at their prestigious headquarters in Belgravia Square. This ultra-modern auditorium made for a most comfortable setting and was enjoyed by an attendance of over 60. In the previous two days, eight health-related apologies had been received with many more from younger members on holidays with their children, as this was half-term week.
The Evening Chairman, John T O’Shea, a Past President of ICorr, began the evening procedures by thanking Dr Fred Parrett, currently Hon. Treasurer of the SCI London Section, for all his work in helping to organise this event. This was an excellent venue and was just around the corner from the Star Pub.
John T O’Shea, a Past President of ICorr, open the meeting
There were two separate presentations – “A Fighting Ship” and “Fighting Corrosion”.
The first presentation “A Fighting Ship” was based around the Mary-Rose project at Portsmouth. This was given by Professor Eleanor Schofield, Head of Conservation and Collections Care at the Mary Rose Trust. Eleanor graduated from Imperial College, where she also received her PhD in Material Science. She has recently received an Honorary Chair at the University of Kent, at Canterbury.
Whilst we are all familiar with the story of the recovery of the Mary Rose in 1982, Professor Schofield began her talk by correcting the too often quoted story that she sank in 1545 on her maiden voyage. In fact she was built in 1510 and served for 34 years as the flagship of Henry VIII’s navy in many battles particularly in wars against France.
Professor Eleanor Schofield giving presentation on “Fighting Ship”
Following the lifting of the ship out of the seabed mud, to prevent further deterioration once exposed to air, the timber hull was treated over many years by spraying with water and polyethylene glycol. Perhaps less well known is the work in restoring and maintaining over 19,000 artefacts that had also been recovered. A significant part of the collection were the 1200 plus iron cannonballs. These have been exposed to sea-water since the ship sank, and the chlorine in sea-water which is very damaging to iron when later exposed to air. This corrosion can eat away at the metal and weakening its structure. It was vital that ways were found of preserving the cannonballs. It was recognised that while the cannons were made to last and be used many times, the cannonballs were only needed for a one-off use. Thus they were greatly inferior in their quality and standards of manufacture.
Initially researchers attempted to remove chlorine from the cannonballs, by soaking in water with and without chemical treatment. Chlorine reduction by heating in an atmosphere of hydrogen was also attempted. Unfortunately, this did not successfully prevent disintegration when they were later put on display. To better understand this, Professor Schofield, established a research project with UCL Archaeology and the UK Diamond Light Source, to understand what was going on inside the cannonballs.
Diamond Light Source in Didcot is the UK’s national synchrotron. It works like a giant microscope, harnessing the power of electrons to produce penetrating bright light that scientists can use to study anything from fossils, to jet engines, to viruses and vaccines.
Diamond’s bright light X-rays combined with absorption spectroscopy, and fluorescence mapping made it possible to visualise the differences in the corrosion profiles. These could be traced to the treatments applied in the 35 years since the cannon balls were recovered with the Mary Rose. The results of the bright X-rays have revealed detailed maps of the elements involved in the corrosive process, an unprecedented insight into conservation on a molecular scale. This crucial information will help protect this and other cultural heritage artefacts for many decades to come.
The second presentation, “Fighting Corrosion” was given by Jim Glynn, a previous Chairman of London Branch and currently the Hon Treasurer. He also runs his own business, Beanny, which is a Coating Distribution Company.
Jim Glynn delivering a presentation on Fighting Corrosion
In his introduction to this presentation, John reminded the audience that the Annual Award of the U R Evans Prize included the presentation of a full-size Sheffield Steel sword, while the H G Cole Award was a mounted poniard (a large dagger). These weapons represent the continued fight against corrosion.
Jim concentrated on the Dynamic Duo, starting with a suitable protective coating as the primary source of defence against corrosion. This should then be supported, where appropriate by a cathodic protection system to prevent any corrosion occurring at holidays or in areas of coating damage. This applies to in-ground and sub-sea structures.
It is often commonly conceived that rusting is a simple, chemical oxidation reaction – but it is not. Aqueous corrosion is however, a complex, multi-stage step process which includes electron transfer at the molecular level. Thus these Electro-Chemical operations during corrosion can be influenced by the external application of electrical potentials. Under the right circumstances, corrosion can be stopped by applying the appropriate level of negative potential using a DC current supply.
Jim presented many examples where the correct conditions of a good coating and a suitable working cathodic potential were present. However, he also described many examples where this was unsuccessful. These included a pipeline coating that had totally disbonded and broken away from the pipeline. This was due to a higher potential than required, which generated hydrogen gas on the surface of the pipeline, causing the damage.
He also described Thermally Sprayed Aluminium (TSA) applications, which are excellent protective coatings when properly applied. The aluminium content can also act as its own in-built cathodic protection anode. However, in the wrong environment, the aluminium can be quickly used up.
Jim expanded his presentation to compare the recent Case Studies of retro-fitting remote anode beds to two similar North Sea rigs. These rigs had exceeded their design life, but it was decided that the sub-sea structure could be further protected using cathodic protection. One had been fully coated with coal tar epoxy, while the legs on the other had been left bare, but with a built-in corrosion factor that should exceed its expected life. The survey confirmed that both could be successfully protected using the methods adopted in the much deeper waters of the Gulf of Mexico.
The coated structure required 1,000 Amps, while the bare steel legs needed around 7,500 Amps to produce the correct comprehensive negative potentials. The location of the anode sea-beds were also calculated. These high DC currents were produced by banks of adjustable transformer rectifiers (TRs) connected to an AC mains electrical source.
Jim also interspersed a number of quiz questions, asking the audience to identify some notable Dynamic Duos in life, film and comic books with several bottles of wine as prizes! This was well received and considered a fun way to conclude the presentations.
The Vote of Thanks was given by Dr Parrett and he presented the speakers with ICorr Engraved Cross pens, as a memento of the evening.
John T O’Shea, Jim Glynn, Professor Eleanor Schofield and Dr Parrett
The first meeting of the new season will be held as usual at Imperial College, on 11th October. The topic will be, “Advanced cathodic protection; protection design by finite method”, by Paolo Marcassoli from Cescor. More details will be available on the Branch page of the Institute website nearer the time.
The second branch joint meeting with the Society of Chemical Industry will be held at SCI, 14 Belgrave Square, London SW1X 8PS, on 25th October 2018 and entitled “A Fighting Ship and Fighting Corrosion” The Speakers will be, Dr Eleanor Schofield – Mary Rose Trust and Jim Glynn – ICorr and Beanny Ltd. The presentations will describe the conservation strategies developed during the restoration of the Mary Rose, and the dynamic duo of coatings and cathodic protection.
The starting time is 17.30 for 18.00, and a net-working drinks reception will follow at 19.30. This event is free to attend, but please register in advance to help with catering at, http://bit.ly/2k6CXUR. Registration can also be made through John O’Shea at, email@example.com. Further details are available on both ICorr and SCI websites.
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 February talk was on the use of Electrochemical Impedance Spectroscopy (EIS) as a predictive tool for coating lifetime, and was given by Dustin Traylor, Global Product Manager of Axalta Coatings Systems. This was an excellent presentation which produced significant discussion amongst those attending. The concept was to raise awareness of new predictive modelling techniques for coating life and performance. A new generation of high temperature coatings, in particular high glass transition temperature Fusion Bonded Epoxy (with a Tg of 205 C), are being developed as a lower cost alternative to expensive alloy steels. However, the highly-functional epoxy resin and ingredients in these new coatings can make interpretation of testing results difficult for coating specifiers. Dustin explored the benefits of using EIS after atmospheric testing to assess a coating’s life expectancy. The conclusion was that EIS did have a part to play in conjunction with accelerated weathering, Autoclave and Atlas Cell tests, to assist in the determination of expected coating life. This technique has now been adopted by Aramco and Chevron and is gaining credibility as a useful tool in the pipeline market.
The branch AGM was held ahead of the March evening technical meeting, at which David Mobbs (Chair) delivered a short presentation on the achievements of the branch over the past year, including confirming that the move to Imperial College had increased attendance from 20-30 to 40-50 per meeting, and that our finances were good. He outlined the steps being taken to obtain speakers to present new technology, new ideas and having more technical content, and noted that the membership affiliated to the branch amounts to 45% of Institute members, and 22 members qualified for 20 or 30 years long service pins. He finished by thanking everyone for their support, and the speakers and committee members who give up their time voluntarily to make it all work.
Mark Stone of Sonomatic Ltd then gave a presentation
on the technology advancements in integrity management
of storage tanks. The industry is well versed with non-intrusive inspection of vessels and pipework, but corrosion mapping of storage tanks has always relied on man entry and physical base plate inspection. However, the industry does not like working in confined spaces and there are moves towards zero-man entry over the lifetime of storage and process vessels. Mark explained that tank inspection plays a major role in effective integrity management of storage tanks, which historically has relied on emptying the tank and personnel entry for cleaning and inspection, and that the common method of using Magnetic Flux Leakage testing is not necessarily the most effective method of determining metal loss. Sonomatic have developed a range of methods for inspection of these tanks while in-service, which includes the use of traditional shell wall inspection using crawlers, coupled with a new technology to determine metal loss of the tank shell using multi skip technology deployed around the outer chine of the tank.
The key element of this testing programme is the use of robotic cleaning and inspection of the floor – the tool is dropped through the tank fluids to the floor and remotely guided by use of sonar. Firstly the level of sludge is determined, and then the tool removes this and scans the base plates, the results of which are transmitted to a mobile unit outside the tank where a statistical analysis is carried out. The presentation included a case study of a field application.
Mark Stone of Sonomatic
This was an excellent presentation and there was a high level of discussion around the floor. The chairman’s opinion was that the real value of this testing procedure was that it was an ‘iterative process’, whereby a tank farm operator could screen all the tanks and identify which were detected as the worst. On opening the tank and carrying out full base plate inspection it would be possible to check the model to see how accurate it was, and by the time the third tank had completed its full inspection, the model would be pretty accurate, and could be used in future with more certainly.
Mark Stone delivered a fascinating presentation on the advancements of Storage Tank Integrity. It’s of particular interest to David Mobbs having been a career objective to establish a mechanism for detecting metal loss on the base plates of tanks without the need to “drop the tank”. The industry is well versed with Non-intrusive inspection of vessels and pipework, but Corrosion Mapping of Storage Tanks has always relied on man entry and physical base plate inspection. The industry does not like working in confined spaces and there are moves towards zero-man entry over the lifetime of storage and process vessels.
Mark Stone explained that Storage Tank inspection plays a major role in effective integrity management of Storage Tanks. Historically, inspection of the floor has relied on emptying the tank and personnel entry for cleaning and inspection and that the common method of using MFL is not necessarily the most effective method of determining metal loss.
Sonomatic have developed a range of methods for inspection of Storage Tanks while in-service. This includes the use of traditional shell wall inspection using crawlers coupled with new technology to determine metal loss in the first meter of the tank using multi skip technology deployed around the outer chime of the tank.
The key element of the program is however the use of a robotic cleaning and inspection of the floor. The tool dropped through the tank fluids to the floor and remotely guided by use of sonar. The first part of the program is to understand the level of sludge which is completed by the sonar that is strategically placed around the base of the tank. The tool is then able to remove the sludge and scan the base plates, results are transmitted to a mobile unit outside where the program is supported by statistical analysis. The presentation included a case study of a field application and the detail can be seen on the LB page of the website
There was a good level of discussion around the floor and it was the view of David Mobbs that this process real value is in an “iterative process” where a tank farm operator would screen all the tanks and identify which was detected as the worst. On opening the tank and carrying out full base plate inspection its possible to check the model to see how accurate it is. By the time the 3rd tank is completed its full inspection the model is going to be pretty accurate. For Copy of the Newsletter please click below;
London Branch News – MAR 18 – Technology Advancements in Integrity Management of Storage Tanks
The presentation given by Dustin was excellent, raising a significant discussion amongst those attending. Dustin’s idea was to raise awareness of new predictive modelling techniques for coating life and performance. A new generation of high temperature coatings, such as high glass transition temperature Fusion Bonded Epoxy (with Tg 205°C), are being developed as a lower cost alternative to expensive alloy steels. However, the highly-functional epoxy resin and ingredients in these new coatings can make interpretation of testing results difficult for coating specifiers. Dustin Traylor, MSE and Dr. Stephen Drew of Axalta Coating Systems explore the benefits of using Electrochemical Impedance Spectroscopy (EIS) after atmospheric testing to assess a coating’s life expectancy. This technique has now been adopted by Aramco and Chevron and is gaining credibility as a useful tool in the pipeline market.
The conclusion was that EIS did have a part to play in conjunction with accelerated weathering; Autoclave and Atlas Cell to assist with the determination of expected coating life.
To verify the laboratory work to date, the Axalta team needs field data on aged coatings to establish if this is an appropriate standard for testing of coatings
For copy of the Newsletter please click below:
London Branch News – FEB17 – The use of EIS