(92a) High Temperature Hydrogen Attack - What Is It? What Is Industry Doing about It?

High temperature hydrogen attack (HTHA) is a damage mechanism most commonly occurring in carbon steel and C-0.5Mo steels that are exposed to hot hydrogen service. The HTHA damage mechanism and historical operating limits (Nelson Curves) for HTHA will be reviewed. Inspection for the HTHA has proven to be challenging as it is a localized damage mechanism that can manifest as either tight cracks or diffuse volumetric damage. Unfortunately, historic design and historic inspection methods have been relatively ineffective.

Assessing HTHA risk can be controversial and has resulted an Industry push for better understanding of the damage mechanism and a shift away from historic operating limit. This resulted in a significant gain in understanding of the damage mechanism and emerging inspection technologies within recent years. Select case studies will be presented and discussed. The direction and steps industry is taking to successfully address HTHA risk and develop tools for integrity programs will be reviewed.