Presenting author: Claus E. Weinell, Hempel A/Se-mail: cwe@dk.hempel.com
Phone: +45 45 27 38 10
Fax: +45 45 27 37 00

Co-author: Soeren Nyborg Rasmussen, Hempel A/S e-mail: snr@dk.hempel.com
Phone: +45 45 27 39 51
Fax: +45 45 93 38 63
Abstract
The demands to protective coatings used in offshore environment are very high and modern high performance paint systems are so durable that they upon exposure to natural weathering may show little signs of deterioration. If an anticorrosive coating is intact during service life it may, for the best present products, maintain a high performance for maybe 15-20 years. The use of new technologies and paint formulations also means coatings being developed with little or no previous track record. This has resulted in more emphasis being placed on accelerated laboratory testing to evaluate coating performance. Many of these accelerated exposure tests will not, within their exposure time show the negative effects visually on intact coated surfaces. Therefore behavior of the coatings around artificially made damages i.e. scores are given significant considerations, and many prequalification tests are based amongst others on rust creep and blistering as well as detachment from scores, NORSOK M-501, ISO 20340, NACE TM 0104, 0204, 0304, 0404 etc.
According to the standards the rust creep is evaluated by a ruler after removal of the paint around the score. In other words the evaluation method is destructive meaning that one panel only gives one reading of rust creep and it is rather time consuming.
This paper presents a new non-destructive testing method which makes it possible to record the progress of rust creep during the exposure time without removing the paint. The advantages are that the same panels can be investigated several times during the exposure time, the method is fast and precise and it provides early predictions of the final rust creep.