The Use of Electrochemical Impedance Spectroscopy (EIS)

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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.

Technology Advancements in Integrity Management of Storage Tanks By Mark Stone – Sonomatic Ltd

Latest News, London Branch

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 3^rd 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[6074]

The Use of EIS as a Predictive Tool for Coating Lifetime By; Dustin Traylor, MSE – Axalta Global Product Manager and Dr. Stephen Drew – Axalta EMEA Coatings Leader

Latest News, London Branch

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[6077]

London Branch Joint Meeting withTWI

Latest News, London Branch

The second presentation of the 17/18 season was a joint meeting with TWI, and James Hesketh of the National Physical Laboratory gave a presentation on the Influence of H₂S on the Pit to Crack Transition in Sour Testing of Corrosion Resistant Alloys.

James Hesketh received a vote of thanks from Stephen Shapcott of TWI on an excellent presentation and received gifts from both TWI and ICorr.

James highlighted that stable pitting is a precursor to sulphide stress corrosion cracking (SSCC), which is one of the main causes of failure of stainless steel pipelines used in sour Oil and Gas production. Despite this, the underlying mechanism governing the growth of such pits is poorly understood, and hence materials selection for sour service is dependent upon costly and time consuming environmental exposure and SSCC test programmes.

In the study at NPL, the role of hydrogen sulphide (H₂S) in pit propagation was investigated as a first step towards the development of accelerated test methods for SSCC resistance. Novel electrochemical techniques were employed to determine the relationship between bulk solution chemistry and the critical pit chemistry required to induce stable pitting in sour environments. James stressed that electrochemical measurements are correlated with results obtained from standard SSCC tests and are rationalised in terms of the balance between H₂S diffusion through the pit mouth, H₂S consumption within the pit and the role of the external cathode.

He also explained that there was a systematic decrease in pit size with increasing H₂S concentration. Also that a greater peak current was measured at higher H₂S concentrations and repassivation was slower.

The 29th London Branch Lunch, held at The Royal Overseas League in early December, was another huge success with 177 people attending the event in Mayfair London.

Guests started to arrive at 11.30 for a pre-lunch  drink and were seated by 12.30 for the first of two acts by The Sirens a group of three singing performers, which was really well received and set the scene for the afternoon. The meal was yet again excellent and congratulations to the ROSL who never disappoint. After the lunch the Chair of London Branch thanked the luncheon organising committee ad the branch committee, who continue to drive the Institute in London forward.

The President then addressed the guests to a rapturous applause once again thanking everyone for their support and explaining that the Institute has exciting plans that will start in Q1 2018.

From left – right, Sarah Vasey, Chris Bridge Simon Bowcock, Trevor Osborne, Charlotte Vie, David Mobbs and Bill Hedges.

After the raffle, two guests were honoured with a small gift in recognition of them receiving the Tallow Chandlers Award for their work in materials and corrosion, a tremendous achievement by Charlotte Vie in 2016 and Simon Bowcock in 2017.   

The timing for the event this year was slightly different allowing guests to socialise and network at the ROSL until 7.00pm which appeared to be extremely popular with lots of notes being taken and exchanging of business cards.

Thanks go again to all those that assisted in the organisation of the event and we look forward to another exciting event in December 2018.  Hamed Habibi, Technical Director of Speir Hunter Ltd, gave an interesting presentation entitled “Developments in Remote Magnetic Monitoring of stress in ferromagnetic Pipeline” at the January meeting.   

The talk introduced and explained the benefits of stress monitoring in pipeline integrity management.   It is the only inspection technique that can simultaneously map the lateral position and depth of cover of a pipeline whilst providing comprehensive defect detection.  Several case studies were discussed to illustrate the advantages of this the technique, also known as Stress Concentration Tomography, over traditional inspection methods.  The technique is able to assess condition of buried pipelines remotely and is not dependent on the type of defect, size of pipe, construction configuration or operating condition, and can  save a considerable amount of time, effort and budget while providing an accurate 3 dimensional mapping of a pipe and surrounding objects.  The technique can also identify location of casings and wrinkle bends, information becoming required by the regulatory authorities.