Hydrogen embrittlement in boiler

Hydrogen embrittlement of mild steel boiler tubing occurs in high-pressure boilers (above 10 bars), when atomic hydrogen forms at the boiler tube surface as a result of corrosion.

Hydrogen permeates the tube metal, where it can react with iron carbides to form methane gas, or with other hydrogen atoms to form hydrogen gas. These gases evolve predominantly along grain boundaries of the metal. The result increase in pressure leads to metal failure. Coordinated phosphate/pH control can be used to minimize the decrease in boiler water pH that result from condenser leakage. Maintenance of clean surfaces and the use of proper procedures for acid cleaning also reduce the potential for hydrogen attack.

High-temperature hydrogen attack in a boiler tube