This standard specifies the test method for determining the cathodic disbonding resistance of coatings exposed to seawater, including: method principle, test solution, test device, test panel and its preparation, test steps, coating inspection and test result evaluation, test report, etc.
The standard is applicable to coatings that are exposed to sea water, such as those applied to ships and marine structures.
This standard is not suitable for the assessment of coatings on land-based structures.
The test methods specified in this standard involves the following:
a) Method A: method of impressed current;
b) Method B: method of sacrificial anode.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding any corrigendum), or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest edition applies.
GB 712 Hull structural steel
GB/T 1765 Method of producing of paint films for testing heat and humidity resistance, salt-fog resistance and accelerated weathering
GB/T 1766 Paints and varnishes - Rating schemes of degradation of coats (GB/T 1766-1995, neq ISO 4628-1:1980)
GB/T 3097 Marine water quality standard
GB/T 3186 Paints varnishes and raw materials for paints and varnishes - Sampling (GB/T 3186-2006, ISO 15528: 2000, IDT)
GB/T 6682 Water for analytical laboratory use - Specification and test methods (GB/T 6682—2008, ISO 3696: 1987, MOD)
GB/T 8923-1988 Rust grades and preparation grades of steel surfaces before application of paints and related products (ISO 8501-1: 1988, EQV)
GB/T 9278 Temperatures and humidities for conditioning and testing of paint specimens (GB/T 9278-2008, ISO 3270: 1984, IDT)
GB/T 13288 The assessment of profile grades of steel surface before application of paint and related products - Comparator (GB/T 13288-1991, neq ISO 85032: 1988)
GB/T 13452.2 Paints and varnishes - Determination of film thickness (GB/T 13452.2-2008, ISO 2808: 2007, IDT)
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
cathodic disbonding
failure of adhesion between a coating and a metallic surface that is directly attributable to cathodic protection conditions and that is often initiated by a defect in the coating system, such as accidental damage, imperfect application or excessive permeability of the coating
