Abstract
In order to investigate the hydrogen induced cracking (HIC) susceptibility of pipe sample in sour gas service, the container type specimen was used, of which body was made from the pipe tested. Three kinds of commercial large size line pipes of API 5LX-60 and X-65 grades were examined for this study. After the half of the volume was filled with test solutions, pure H2S gas or mixture of N2 and H2S was bubbled. The test solutions were synthetic sea water, pure water and synthetic sea water mixed with crude oil. After controlling the concentration of H2S, the containers were kept for about one year as they were. In order to know the development of cracking during the test, ultrasonic testing was used.
As the results of this investigation, it was clarified that the development of HIC was due to the environment, steels, mill scale and so on. It was also obtained that HIC susceptibility of steels evaluated by the standard HIC test method which was recently developed by Kowaka et al, correlated wtih that evaluated by this long duration exposure test, although the investigation of environmental factors was important for the prevention of HIC.
