Considerations on the Risk of Hydrogen Embrittlement of Pipeline Steel due to Cathodic Overprotection
Proceedings Publication Date
Dr. Hanns-Georg Schöneich
Dr. Hanns-Georg Schöneich
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The risk of hydrogen embrittlement of pipeline steel due to cathodic overprotection has frequently been described in literature. ISO 15589-1 mentions this risk for pipeline steels with specified minimum yield strength exceeding 550MPa (N/mm2) and requires to investigate the limiting cp-potential (at the steel/soil phase boundary). Furthermore there is some evidence from literature that a combination of mechanical damage and cathodic overprotection can lead to rapid failure due to hydrogen embrittlement. On the other hand, however, the operation of a cathodic protection system requires the adjustment of a fairly negative on potential, e.g. in order to compensate local anodic potential gradients that cause an anodic interference. Furthermore in case of risks due to alternating current corrosion EN 15280 recommends adjusting the cp on-potential to a sufficiently low level in order to establish a current ratio Jac/Jdc

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