To understand the effect of TSA coating damage on the life expectancy of coated offshore structures.
The corrosion testing of coatings which are anodic with respect to the substrate alloy on which they have been applied typically uses test coupons with simulated damage introduced by the removal of 5% of the coating and exposure of the underlying substrate. There are, however, no published data defining the upper limits of acceptable damage or the size and distribution of coating holidays making up a particular percentage. This project will attempt to determine the damage tolerance of TSA coatings on C-steel when immersed in (synthetic) seawater at room temperature. Examples of test coupon total holiday percentage levels and sizes of holidays comprise:
- 5% (1 x 5%, 5 x 1%)
- 10% (1 x 10%, 2 x 5%, 5 x 2%, 10 x 1%)
- 15% (1 x 15%, 3 x 5%, 5 x 3%, 15 x 1%)
Outputs recorded will comprise potential of coated test coupons and linear polarisation resistance data for a period of up to 3 months. Coating corrosion rate will be calculated and correlated with the remaining TSA coating and calcareous compounds deposited from the synthetic seawater test solution.
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Technical and Economic Benefits
This will give baseline data for cathodic protection design when using TSA in subsea applications. The application of TSA without any externally applied anodes or impressed current cathodic protection system is likely to reduce costs significantly.