Hydrogen Attack Evaluation

The presence of hydrogen in industrial plants is a potential source of damage. High partial hydrogen pressure (higher than 30 bar) and high temperature (higher than 300 ºC) can negatively influence the material’s characteristics. Such damage occurs largely in fertilizer plants and refineries.

Hot Hydrogen Attack (HHA) is a form of degradation caused by carbides reacting in steel, thereby forming methane (CH4).The probability of HHA damage in industrial plants is dependent on its partial hydrogen pressure and operating temperature. In the worst cases, HHA may lead to a leak before an actual break situation, but when the damage is in the parent material, the results can be catastrophic.

Enkon developed a specific procedure and approach to adequately identify and monitor HHA.

The methodology developed by Enkon combines advanced signal processing and results imaging utilizing advanced techniques like Time of Flight Diffraction (ToFD),Automated Backscatter and Velocity Ratio Measurements.

To inspect a plant for the possible occurrence of Hot Hydrogen Attack, an accurate inspection plan has to be made with the back scatter technique using Corroscan for the most critical areas, i.e., at highest temperature and/or highest partial hydrogen pressure. In order to discriminate between HHA and small inclusions and to verify any attack, additional measurements are taken with the velocity ratio technique.

The approach in the field would involve complete scanning of all welds with ToFD (if accessible) and manual or automated Pulse Echo.

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Application Range