Abstract
Two case studies of hydrogen related cracking in chemical plant are introduced.
Case one is the cracking of tantalum (Ta) parts in sulfuric acid containing environment. In this case, the hydrogen is absorbed in Ta parts during operation condition. The relationship between hydrogen concentration and mechanical properties, the possibility of de-hydrogen heat treatment and the nondestructive evaluation method for measuring the hydrogen concentration are studied.
Case two is the cracking of molybdenum containing nickel base alloy. The controlling factors for cracking are studied by the potential controlled slow strain rate test. It becomes clear that the ordering of the alloy by the heat treatment during fabrication and the absorption of hydrogen during operation are promoting factors for cracking.
From these studies, it is recognized that the root cause analysis is important to take the appropriate counter measurement.
