1. Report on
Hydrogen attack
Name: ‫ﻓﺮﺝ‬ ‫ﻣﺤﻤﺪ‬ ‫ﻣﺤﻤﻮﺩ‬‫ﺃﺣﻤﺪ‬
Section: 7
No: 169

2. High Temperature Hydrogen Attack (HTHA)
Explanation
High temperature hydrogen attack (HTHA) is a phenomenon, which occurs within some industrial
processes when the presence of hydrogen, subjected to high temperature and pressure, makes plants and
systems susceptible to damage, many similar effects have been observed in different structural materials, such as
steel, aluminum, titanium, and zirconium.. This reaction can cause an industrial plant to suffer serious failure,
which may lead to both expensive repairs and loss of production.
Detection
HTHA can be detected in a number of ways, but it is considered that with the complexity of HHTA a more
structured approach is necessary. A series of procedures have been developed featuring the latest
advances in ultrasonic imaging and data processing techniques in order to achieve a greater level of
confidence in both HTHA inspection results and inspection repeatability.
Classifications
Hydrogen damage may be of four types: solid solution hardening, creation of internal defects, hydride
embrittlement, and hydrogen embrittlement. Each of these may further be classified into the various
damaging processes.
TYPICAL CHARACTERISTICS OF DAMAGE
The most important features of hydrogen damage are summarized in :

3. Importance
With advancing technology, use of high strength structural materials becomes a necessity. Depletion of
fossil fuels and the search for other sources of energy is a current activity of humankind. Hydrogen is
believed to be a possible future source of energy (Engineering note: Hydrogen could not be used as a
"source" of energy but only as a means to transport energy from one place to another) and a “hydrogen
economy” is a strong possibility within the next 50 years. In such a scenario, large‐scale production,
storage, transportation and use of hydrogen becomes necessary. Materials’ problems caused by hydrogen
damage could limit the progress of such an economy. Metals may pick up hydrogen during melting,
casting, shaping and fabrication. They are also exposed to hydrogen during their service life. Materials
susceptible to hydrogen damage have many opportunities to be degraded during all these stages.
Control of hydrogen damage
The best method of controlling hydrogen damage is to control contact between the metal and hydrogen.
Many steps can be taken to reduce the entry of hydrogen into metals during critical operations like
melting, casting, working (rolling, forging, etc.), and welding, surface preparation, like chemical cleaning,
electroplating, and corrosion during their service life. Control of the environment and metallurgical control
of the material to decrease its susceptibility to hydrogen are the two major approaches to reduce
hydrogen damage.
Mechanism of failure
Excessive deposits of feed water corrosion products such as iron, copper or nickel oxides or oxide hydrates
themselves are not sufficient for the development of hydrogen damage. The second condition is the
presence of acidic contaminants in the boiler water and their concentration underneath the deposits (e.g.,
by wick boiling).
Figures