The branch kicked off 2018 with 3 well attended events with an average attendance of over 60 people, beginning with a special cathodic protection evening on the 30th of January. In the first of two presentations, Edgar Rodrigues of TAQA gave an excellent talk on “Impressed Current Cathodic Protection Retrofit Strategy in the North Sea”.
TAQA’s fixed drilling and production installation was installed in the North Sea in 1980 in 161 metres water depth approximately 110 miles north-east of Lerwick in the Shetlands. The platform jacket has 8 legs and was installed with traditional stand-off galvanic anodes, but its sacrificial CP System is now beyond its original design life. Surveys from 2010 to 2013 indicated a reduction in corrosion protection from the CP system, and plans were implemented to upgrade this. A remote impressed current CP (ICCP) anode sled system was selected, installed and commissioned in early 2016. This presentation discussed the CP design process and the many challenges in choosing what was at the time, the largest ever CP retrofit, both in terms of delivered current capacity offshore, and the CP current demand of the structure required to maintain external corrosion protection. All retrofit CP systems however require regular CP data to validate CP performance and this can often be erratic and costly to obtain, typically involving ROVs, as was discussed in the second presentation of the evening.
Andy Smerdon of Aquatec Group continued the evening with a very interesting and complimentary presentation on “Retrofit CP Monitoring to Reduce Inspection Frequency”. Aquatec was founded by the current managing director in 1990 as a specialist consultancy in oceanographic instrumentation design. This presentation described a CP toolbox within a UK North Sea case study, comprising monitoring and communications modules that were used to provide high quality CP potential and CP current data sets, accessed remotely from diving vessels and platforms. The cost of CP monitoring equipment when simultaneously installed with retrofit CP systems, is relatively low and normally recovered by dispensing with just one conventional subsea inspection campaign, in favour of remotely retrieved data.
The branch’s second event in January, took place at the School of Mechanical Engineering at Aberdeen University, where a Corrosion Awareness training session was held. In the packed two hour event, there were 6 presentations covering corrosion theory and failure mechanisms, principles of corrosion management, materials and coatings selection, risk based inspection, cathodic protection, chemical and corrosion monitoring, all of which prompted a number of interesting questions from the enthusiastic audience.
Retrofit CP Monitoring
In recent years, ICorr Aberdeen has established a strong working relationship with the Aberdeen branch of IMECHE and in particularly its Young Engineer Panel, and a further more extensive Corrosion Awareness event will follow in August 2018, details will be announced in the May/June magazine, and on the branch website.
The February event focused on internal corrosion management Issues, particularly corrosion mitigation by chemical control and optimisation. A very enjoyable and informative presentation was given by Emma Perfect, CEO of LUX Assure Ltd, who described the development of an onsite technique for measuring dosage of corrosion inhibitors used in the protection of pipelines. This advanced technique was developed as there was a perceived need to identify more quickly, and more accurately, when dosing levels of inhibitor were either below or above the threshold for protection, and hence allow an operator to adjust levels to better protect equipment from corrosion, or have options to lower the dosage level to reduce costs of inhibitor supply.
Development of the LUX Assure Control Concept commenced in 2008 and the company has been supported by key energy industry players including Chevron, ConocoPhillips and Statoil Technology Ventures, along with the Scottish Investment Bank and Archangels / Private Investors. The technique relies on the fact that corrosion inhibitors form micelles in the body of the fluid once all available sites for absorption are occupied. This is essentially a saturation point, and the micelles formed increase in concentration as inhibitor is supplied in excess of optimal levels.
With access provided to suitable trial sites, the development of the technique and a suitable kit for onsite monitoring progressed over a period of 3-4 years until it was fully commercialized in 2013. LUX Assure gathered data to show operators that this technique could be used to test fluids and identify the Critical Micelle Concentration (CMC) of a surfactant above which micelle formation occurs. But the real challenge for LUX Assure was to develop a kit, (now known as CoMicTM) which operators offshore could use to sample and analyse fluids in the field in relatively uncontrolled environments without precise preparation. The specialised kit includes detection reagents and an optical analyser. Final data processing evaluation of the sample is still currently performed back at the offsite laboratory and results and advice swiftly communicated back to the field, but a full onsite service is currently being progressed.
CoMic Testing Kit
The presentation, which was well received, went on to describe case studies and discuss when samples may not be suitable for testing, and also the correct use and interpretation of the data for the test situation. It is hoped that in the near future that all data interpretation can be made by the test operator if a practical and proven site assurance system can be developed.
For information about all forthcoming Aberdeen branch activities, please contact, Dr Yunnan Gao, ICorrABZ@gmail.com, alternatively a calendar of local events of interest to corrosion professionals in the Aberdeen area and the opportunity to sign up to the branch mailing list is available at https://sites.google.com/site/icorrabz/home
