Technical Presentations at the October 2017 Meeting

1.1   ‘Corrosion Protection of Offshore Structures using Thermal Spray Coatings’, Shiladitya Paul, TWI

Thermally sprayed aluminium (TSA) has been used in offshore service for decades. The low corrosion rate of aluminium coupled with its electrochemical nature ensures protection of offshore steel structures. TSA protects steel by acting as a barrier when intact and by sacrificial action when damaged. The efficacy of TSA in protecting steel when damaged has been studied before, but the effect of damage has not been studied in detail. TWI is carrying out several projects to look at the behaviour of TSA when damaged. This talk aims to inform the audience of TWI’s ongoing work in the field


1.2  'Performance of Thermal Spray Aluminium (TSA) in Marine Environments - A fundamental study of the effect of seawater constituents’, Rosa Grinon, University of Leicester

Selection of coating systems and their subsequent application in marine environments requires the knowledge of their performance in seawater, UV, and under thermal and mechanical loading. Coatings which have been used in specific areas of offshore structures in certain geographical locations for decades may not be suitable in other areas or locations. For example, thermal spray zinc is often used for top side of offshore structures, but they perform poorly when immersed in seawater. Thus, fundamental understanding of the performance of sacrificial coatings in marine environments is important. Detailed understanding of how the marine environment (for example, Cl-, Mg2+, Ca2+ etc.) interacts with structures coated with thermal spray sacrificial coatings (such as Al, Zn) is lacking. Further, the long-term performance benefits offered by these coatings are largely anecdotal.

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4.1  ‘Interpreting Offshore CP Field Data’, Alex Delwiche, Deepwater EU Ltd

The discussion was about how cathodic protection field data is not necessarily interpreted as perhaps it should and that there are many anomalies that are often “hidden”, skewing actual events. Several case studies will be presented showing the results of several situations whereby ICCP systems, temporary or permanent, show interesting results of the effects of applying CP in an marine environment


4.2  ‘Corrosion of Cemented Tungsten Carbide (WC-Co) with a View to Understanding Degradation of Drill Bits’, Stephen Herd, Southampton University

.Cemented tungsten carbide (WC-Co) is a well-established material that is ideally suited to high abrasion environments due to its excellent hardness and fracture toughness. Previous studies of worn drill bits have found that they are subject to both mechanical and corrosive degradation mechanisms, called a tribocorrosion system. The combined result of these degradation mechanisms produces high and sometimes unpredictable wear rates that lead to challenges in prediction of component service life. The corrosion processes of WC-Co is still debatable, with conflicting findings in the literature. A combination of electrochemical tests and post analysis techniques of the surface are used to systemically study corrosion behaviour of WC-Co in acidic (H2SO4) and alkaline solutions (NaOH). Through understanding the differences in these corrosion mechanisms it is possible to assess what the corrosion environment was from analysis of drill bits. Ultimately, this understanding of the microstructure will help to inform the modelling of a WC-Co tribocorrosion system.

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