Metallurgical damage caused by hydrogen in boiler circulation systems — Conclusions from case histories and prevention

Decarburization and resulting intergranular disintegration of steel due to action of nascent hydrogen evolving in corrosion reactions in a boiler may result in tube failures in the circulating system of boiler.

The main players in this type of damage are identified as: (a) oxygen in boiler feed water, (b) condensate contamination by condenser leakage, (c) copper pick up from low pressure heaters and condenser tubes, (d) high heat flux on tubes and lower mass flow, (e) localized strain and stress concentration (f) existence of a visible corrosion and products of corrosion already lodged on the surface.

The tube damage by hydrogen can be avoided by properly addressing the above factors.