How do you prevent hydrogen induced cracking?

How do you prevent hydrogen induced cracking?

Hydrogen-induced cracking can be prevented through:

1. Control of stress level (residual or load) and hardness. Computer software H2Compass can be used to determine when PWHT or Pre-Heating is required. Click here for details on the H2Compass software.
2. Avoid the hydrogen source.
3. Baking to remove hydrogen.

What causes stress corrosion cracking?

Stress corrosion cracking (SCC) is the cracking induced from the combined influence of tensile stress and a corrosive environment. The impact of SCC on a material usually falls between dry cracking and the fatigue threshold of that material.

What causes hydrogen cracking?

Cracking usually occurs at temperatures at or near normal ambient. It is caused by the diffusion of hydrogen to the highly stressed, hardened part of the weldment.

What is hydrogen induced cracking in welding?

The presence of hydrogen in the weld metal or HAZ may lead to a form of cracking known as hydrogen-induced cracking (HIC). This form of cracking is also commonly referred to as “hydrogen-assisted cracking” (HAC) or “cold cracking” since it occurs at or near room temperature after the weld has cooled.

Where does hydrogen induced cracking occur?

2 Hydrogen induced cracking (HIC) HIC occurs in carbon or low-alloy steels when atomic hydrogen diffuses into it and forms molecular hydrogen. Formation of molecular hydrogen may be facilitated by inclusions or trap sites. Therefore HIC can occur in the absence of any stress.

Where does hydrogen cracking occur?

Hydrogen cracking is sometimes referred to as delayed cracking because it can occur up to 72 hours after the welding is completed. These cracks can occur in the weld metal or heat-affected zone (HAZ), which is the area adjacent to the weld that didn’t melt.

How do you know if stress corrosion are cracking?

A close-up of the surface of a steel pipeline showing stress corrosion cracking (two clusters of small black lines) revealed by magnetic particle inspection. Cracks which would normally have been invisible are detectable due to the magnetic particles clustering at the crack openings.

What is HIC test?

Element offers Hydrogen Induced Cracking (HIC) tests to accurately assess the susceptibility of your carbon and low alloy steel equipment to hydrogen induced cracking in wet H2S/sour service operating environments such as in the Oil & Gas industry. The tests are normally carried out according to NACE TM0284.

Does hydrogen cause corrosion?

Corrosionpedia Explains Hydrogen Damage With hydrogen damage, multiple metal degradation processes occur due to interaction with hydrogen. For example, in boiler tubes, hydrogen damage is caused by a corrosive reaction between steam and steel, resulting in decreased material strength and localized corrosion.

What causes hydrogen embrittlement in steel?

Hydrogen Embrittlement occurs when metals become brittle as a result of the introduction and diffusion of hydrogen into the material. The degree of embrittlement is influenced both by the amount of hydrogen absorbed and the microstructure of the material.

Does hydrogen make metal brittle?

However, for metals like steel, aluminum and magnesium – which are commonly used in automotive and energy technology – hydrogen is not quite ideal. It can make these metals brittle; the ductility of the metal becomes reduced. Its durability deteriorates. This can lead to sudden failure of parts and components.

What is HIC score?

The head injury criterion (HIC) is a measure of the likelihood of head injury arising from an impact. The HIC can be used to assess safety related to vehicles, personal protective gear, and sport equipment.

What is HIC and SSC test?

In high-strength steels cracks can arise in the zone that had been affected by heat in weld seams due to the action of mechanical stress in atmospheres containing hydrogen sulphide. The testing of materials with regard to this damage mechanism, “Sulphide Stress Cracking“ (SSC) is done in accordance with NACE TM 0177.

How does hydrogen ions affect corrosion?

With the increase of hydrogen dissolved in the metal, the concentration of dissolved ion, corresponding to the corrosion rate of the sample, increases significantly. Hydrogen can promote the anodic oxidation and reduce the stability of the passive film.

How does hydrogen affect steel?

Hydrogen gas can adsorb and dissociate on the steel surface to produce atomic hydrogen. 2,3 The subsequent dissolution and diffusion of atomic hydrogen into steels can degrade mechanical properties, a phenomenon generally referred to as hydrogen embrittlement.