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Severe Sour Service

An environment with high concentration of hydrogen exposure, (H2S), can potentially diffuse into the steel. This can lead to embrittlement and potentially create inclusions.

Hydrogen Induced Cracking (HIC) can occur where there is a high concentration of hydrogen. This type of cracking can initially appear as a small blister. Atomic hydrogen can form in a wet H2S environment and potentially able to diffuse into the steel.

To support applications where there is an exposure to wet/sour
service, American Alloy Steel designed our TUF 37 steel plate:

Certified to SA 516-60 / SA 516-65 / SA 516-70.

TUF 37 has the following qualities:

Low Sulfur .002% max
Low CE .37 average for better weldability
Produced to a Fine Grain Practice, Vacuum degassed, and Sulfide Shape Control.
All material is normalized for excellent fracture toughness / high resistance to notch sensitivity for low temperature applications.

Stress Oriented HIC (SOHIC) cracks tend to occur perpendicularly and are driven by stresses – residual or applied – and tend to occur most often around the HAZ (Heat Affected Zone) of a
weld. Like HIC Cracking, SOHIC cracking occurs when atomic hydrogen diffuses into equipment and collects at impurities within the steel.

This is more prevalent in acidic / hydrogen rich environments where the H2S is over 50 ppm and temperature is under 180 F.