Hydrogen induced cracking refers to internal lesions which arise because of material caught in budding hydrogen atoms. Atomic hydrogen diffuses into a metallic structure and becomes saturated, which may lead to the loss of mechanical properties. If the buildup of molecular H is repressed, the atomic H can enter the metal instead of forming a gaseous reaction. This forms a crack in the metal, decreasing the strength. Hydrogen induced cracking-resistant steel mitigates this risk.
Hydrogen induced cracking steel plate is used in applications in which hydrogen induced cracking is a big risk, such as in boilers. It is particularly common in the gas and oil industry where steel pressure vessels are frequently used. These risks should be measured when the partial pressure of hydrogen sulfide is more than 3.5mbar.
HIC is most common in wet H2S environments, referred to as sour service, bringing cracking over an extended period. This could eventually lead to the entire pressure vessel failing.
How to Make Hydrogen Induced Cracking Resistant Steel
There are two main ways to create hydrogen induced cracking steel plate which will be outlined here.
The first way is to shape the manufacturing process of the steel around the requirements, forming steel that is extremely high quality and corrosion-resistant. This allows the hydrogen induced cracking resistant plate to be consistently and reliably produced, able to pass any retests.
This second means of production is by producing a standard boilerplate, then testing the best heats and measuring whether they meet the requirements. This leads to hydrogen induced cracking resistant steel being produced more cheaply because of the lower initial investment needed. Because testing is carried out on a sampling basis, the risk of the plates not meeting regulations is much higher.
Making hydrogen induced cracking resistant steel deliberately requires the consideration of several main factors to make it the best possible quality. The metallurgy of the steel needs to be controlled, best done by undertaking primary metallurgy and measuring the ladle composition. Then the steel-making process is repeated and fine-tuned.
Key Differences between HIC and SOHIC Problems
Stress-oriented hydrogen induced cracking is another issue that arises from exposure to hydrogen sulfide in wet and sour service environments.
There is a difference in the cracking pattern and the stress load is impacted in the heat-affected zone of welds. SOHIC happens most frequently where there is elevated hydrogen activity.
Combatting the Problem of Hydrogen Induced Cracking
Hydrogen induced cracking resistant steel plates are tested to ascertain the susceptibility of the material to hydrogen induced cracking. MASTERHIC from Masteel can be used for fine-grain pressure vessels, providing exacting properties for sour gas application.
Masteel are experts in the field and can offer detailed insight into the type of hydrogen induced cracking tested steel that suits each application.
If you would like to learn more about hydrogen induced cracking, visit this page for more information.