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Different Types of Corrosion
- Recognition, Mechanisms & Prevention

Hydrogen Blistering

Recognition of Hydrogen Blistering

What is hydrogen blisteering?

Hydrogen Blistering (HB) refers to the formation of subsurface planar cavities, called hydrogen blisters, in a metal resulting from excessive internal hydrogen pressure. Growth of near-surface blisters in low-strength metals usually results in surface bulges.

Mechanisms of Hydrogen Blistering

What causes hydrogen blistering? Hydrogen ions are reduced to hydrogen atoms that adsorb on the steel surface. Some of the hydrogen atoms will diffuse through the steel and accumulate at hydrogen traps, typically voids around inclusions.

When hydrogen atoms meet in a trap and combine, they form hydrogen gas (H₂) molecules in the trap. The accumulation hydrogen gas inside the extremely small cavity will lead to the buildup of excessive internal hydrogen pressure. At certain times, this internal hydrogen pressure will become sufficient to cause the steel to blister.

Blisters occur usually in low strength steels (<80ksi yield strength) and are formed preferentially along elongated nonmetallic inclusions or laminations in linepipe steels.

Modeling, Prediction, and Prevention of Hydrogen Blistering

How to select alloy steels for resistance to Blistering?
How to calculate atomic hydrogen concentration in steels?
How to calculate internal hydrogen gas pressure in steels that can cause internal blistering?
How to determine if post-weld heat treatment (PWHT) or pre-heating is required?
How to assess the susceptibility of an alloy steel to low temperature hydrogen damages such as hydrogen blistering (HB), hydrogen-induced cracking (HIC), stress-oriented hydrogen-induced cracking (SOHIC), stepwise cracking (SWC), hydrogen embrittlement (HE), hydrogen stress cracking (HSC), sulfide stress cracking (SSC), and soft zone cracking (SZC)?

H2Compass is a powerful software for modeling and prediction of low temperature hydrogen damages and high temperature hydrogen attack (HTHA). H2Compass software provides instant answers to the above questions. The software can be used to determine the atomic hydrogen concentration in steels, the internal hydrogen gas pressure at hydrogen traps in steels, the steel's susceptibility to low temperature hydrogen damages, and the requirements for post-weld heat treatment (PWHT) and pre-heating.

Hto prevent hydrogen blistering? Hydrogen Blistering can be prevented through:

• Control of impurity of steel.

• Avoid the hydrogen source.

• Baking to remove hydrogen.

For more details on Hydrogen Blistering

Where can I learn more about hydrogen blistering? More details on hydrogen blistering are included in the following corrosion courses which you can take as in-house training courses, course-on-demand, online courses or distance learning courses:

Corrosion and Its Prevention (5 days)
Environmental Cracking (HB-HIC-SWC-SOHIC-SSC-SZC-HSC-HE-SCC): Recognition, Mechanisms and Prevention (5days)
API 571 Damage Mechanisms Affecting Fixed Equipment in the Refining and Petrochemical Industries (5 days)
Corrosion, Metallurgy, Failure Analysis and Prevention (5 days)
Marine Corrosion, Causes and Prevention (2 days)
Materials Selection and Corrosion (5 days)

If you require corrosion expert witness or corrosion consulting service on hydrogen blistering, our NACE certified Corrosion Specialist is able to help. Contact us for a quote.

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