Research

External corrosion on a pipeline depends greatly on the long-term performance of the barrier coatings used to protect it. If coating systems fail prematurely, they cannot be economically replaced.  Cathodic protection could help alleviate this issue, but its effect will be limited in the case of disbondments. Thus, knowledge-based coating selection and control of application procedures are of paramount importance for achieving low CAPEX objectives.

Unfortunately, the tools that corrosion engineers have at their disposal have limited power. Current quality assurance (QA) test results only allow to rank coating systems according to their performance under testing conditions, but do not allow to estimate in-service performance. In-service performance estimations are based on previous experiences, which are not necessarily comparable. This leads to a precarious condition where small changes in formulation or service conditions can lead to unsatisfactory results. In addition, testing the coatings using pre-qualification standards can occasionally result in false positives, where a coating passes all tests, but then performs poorly in service.

This project increases the reliability of coating selection tests by studying the effect of additional contributing factors, such as mixing ratio and testing under wet conditions, and by comparing accelerated laboratory test with controlled field exposures. Two approaches are taken to investigate the coating QA testings:

• One approach uses a combination of standard and non-standard coating testing methods to evaluate, in a short period of time, the likelihood of premature failure of several commercial two-part epoxy coatings.
• The second approach focuses on validating that the degradation process evaluated through short term testing are the same as those experienced in service.

The project provides industry with a stronger knowledge for the selection and pre-qualification of coatings. It also will develop quality assurance and validation test against realistic and comparable long-term performance. Validated QA tests will increase the confidence on coating/application process selection and help to prevent the extremely high costs associated with repair and management of inadequate coating systems. Direct contributions to relevant Australian or international standards also are expected as the project’s outcome.

Douglas Proud

Research & Utilisation Program Coordinator

douglas.proud@futurefuelscrc.com