Cathodic disbonding, blistering, and current demand for cathodic protection were measured for nine commercial coatings for submerged steel structures. The ASTM-G8 standard test and a long-term test (2 years), simulating North Sea conditions, were used. The relevance of the ASTM-G8 test as a prequalification test was evaluated by comparing cathodic disbonding in the two tests. After 800 days in the long-term test, the correlation to ASTM-G8 was good. The correlation coefficient was 0.98. The current demand for cathodic protection increased when the coating blistered. Examination of the blisters showed that they had cracked. After 2 years of testing, the current demand only had increased for the coatings (<150 micrometers). The current demand for the thicker coatings (>450 micrometers) had not increased, in spite of significant cathodic disbonding for some coatings. Coating breakdown factors, defined as the ratio between current demand for cathodic protection for the coated samples and samples of bare steel, were calculated. These factors were compared with the design values for cathodic protection in Det Norske Veritas (DNV) RP B401 and NORSOK M-CR-503. For all coatings, the coating breakdown rate was lower than the design values.
Effects of cathodic disbonding and blistering on current demand for cathodic protection of coated steel
Einfluß der kathodischen Enthaftung und der Blasenbildung auf den Strombedarf für den kathodischen Schutz von beschichtetem Stahl
Corrosion, Houston ; 56 , 3 ; 256-264
2000
9 Seiten, 10 Bilder, 3 Tabellen, 30 Quellen
Article (Journal)
English
Factors influencing the rate of cathodic disbonding of coatings
Tema Archive | 1994
|British Library Online Contents | 2015
|