Technical Presentations at the January 2010 Meeting

1.1   ‘A Nanocomposites Approach to Environmentally Friendly Anti-corrosion Coatings’, John Hay and Lyndsey Mooring, University of Surrey 

Clays consist of parallel sheets (platelets) of aluminosilicates, typically about 1 nm thick, which are held together by forces such as ionic bonding to form much larger aggregates of a few micrometres in size.  While such aggregates find extensive use as additives for plastics and paper, of arguably more interest are systems where the clay platelets have been separated by polymer molecules to form so-called nanocomposites.  In these materials, nanoscale clay platelets are dispersed within the polymer to form either intercalated or exfoliated polymer nanocomposites (PNCs).  

 

 

These PNCs display a number of interesting properties, including very good barrier properties.  This makes them strong candidates for applications in corrosion-resistant coatings.  In this presentation, the development of novel PNC coil coatings was described, including details of their characterisation.  The results of humidity and outdoor exposure testing (by Beckers) were presented.  These demonstrate that some of the PNCs have the potential to replace existing environmentally unfriendly chromium-based systems as anti-corrosion coatings.   [j.hay@surrey.ac.uk]

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1.2  Keynote: ‘Marine Corrosion Control – the Good, the Bad and the Ugly’, David Moran, Lorina Corrosion Control 

David feels like the corrosion equivalent of Clint Eastwood sometimes when inspecting ships.  He likes to take on the bad guys in the industry, making ships safer and easier place to be for the maintenance crew. 

David is ‘the engineer you have never heard of’ but identifies what he considers good, bad and ugly about the industry which has been a part of his career for 35 years. 

The Good is the progress over this period in understanding corrosion and the development in methods of preventing it.  The Bad is the lack of enthusiasm and excitement for our industry which was present in the 70’s and 80’s when real development took place.  This development was probably fuelled by the offshore industry which invested large quantities of money into corrosion prevention. 

The Ugly is the downward pressure on good practise, quality control and pride which does not reap the same reward as for complacency, sloppy work and sales.  Quality control is a paper exercise not a reality. 

There are safety issues also at stake that need addressing, particularly the ships hull integrity which can be jeopardised by corrosion. 

David gave a range of examples to illustrate the points made but concluded that these issues are easily remedied if those able to make it happen provide the necessary leadership.  Bring back the corrosion ‘shamans’ of the past. 

David provided the type of remedies that are in his opinion required.

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3.1    ‘Recent Impressed Current Offshore Cathodic Protection Solutions’, Jim Britton, Deepwater Corrosion Services Inc 

When offshore steel structures need life extension, this invariably involves the cathodic protection system at some point.  In some cases the economics of using impressed current solutions are very persuasive.  This is particularly true as total system current capacities exceed 10,000 Ampere-Yrs, but there are other factors which present difficulties for sacrificial anode solutions.  

This talk presented several case histories where new impressed current technologies and system combinations have been employed on a wide variety of offshore structures.  These case histories focused on why the installed system was selected.  Systems presented were all projects completed by the presenters company in the last 5 years.  These included a Fixed Platform (North Sea/Gulf of Mexico), a Wind Farm (Irish Sea), an FPSO (West Africa), a SPAR (Gulf of Mexico) and a large Jetty structure (Canada). 

[Jim Britton CEO, Deepwater Corrosion Services Inc, 10851 Train Court, Houston, Texas 77041, 713-983-7177, jbritton@stoprust.com]

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3.2   ‘Corrosion Experience with 'Marine' Aluminium Alloys’, Ben Hooker, Babcock 

Discussion of typical material selection criteria that lead to the use of 5083 and other aluminium alloys in unsuitable saltwater environments.  A case study of a 6m catamaran residing in unflowing, de-aerated basin water was used to illustrate the limitations of otherwise sound corrosion prevention methods.  The limits of aluminium's passivity in different pH ranges and limited oxygen for film regrowth resulted in aggressive pitting.  The structure was unpainted, alluding to the arrogance or ignorance of the designers regarding the environment this vessel was expected to survive in.  Similarly to how stainless steels are perceived in the engineering community, aluminium suffers from its own reputation as a corrosion-resistant material by being chosen for a multitude of corrosive environments, often without regard for effective maintenance schedules.

Note: Several of these presentations are available in pdf format to staff of MCF member companies.  Please contact the Secretariat for details.

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