ArcelorMittal Lázaro Cárdenas, Mexico has begun producing slabs to be used in pipelines that transport sour gas, a natural gas containing significant quantities of toxic gases such as hydrogen sulfide (H2S), carbon dioxide (CO2), or similar contaminants.
In order to be suitable for this use, the steel slabs must present very stringent technical specifications, including a high resistance against hydrogen-induced cracking (HIC).
In order to be suitable for this use, the steel slabs must present very stringent technical specifications, including a high resistance against hydrogen-induced cracking (HIC).
For this reason, the site must produce defect-free slabs with a reduced centre segregation rate.
The H2S present in the sour gas poses a major challenge: this compound reacts with water creating a corrosion mechanism due to the release of hydrogen in diatomic and monatomic form. The monatomic hydrogen diffuses through the steel and becomes trapped in voids in the metal microstructure, giving rise to brittle areas when these atoms recombine to form hydrogen molecules. This creates pressure mechanisms, leading to the formation of blisters and subsequently micro-cracking, which can result in the failure of the metal with potentially disastrous consequences.
The H2S present in the sour gas poses a major challenge: this compound reacts with water creating a corrosion mechanism due to the release of hydrogen in diatomic and monatomic form. The monatomic hydrogen diffuses through the steel and becomes trapped in voids in the metal microstructure, giving rise to brittle areas when these atoms recombine to form hydrogen molecules. This creates pressure mechanisms, leading to the formation of blisters and subsequently micro-cracking, which can result in the failure of the metal with potentially disastrous consequences.
To test the steel’s resistance, an HIC test, developed by the US association of corrosion engineers (NACE), is carried out. The steel is placed in an acid bath for 96 hours to see if cracking occurs. The tolerance level is dictated by the customer.
After undergoing several tests, ArcelorMittal Mexico met all the requirements of its customers in this project, world leading tube manufacturer Welspun Corp in India, and leading coils plate producer, Ternium in Mexico with the internal quality of the slabs exceeding expectations.
After undergoing several tests, ArcelorMittal Mexico met all the requirements of its customers in this project, world leading tube manufacturer Welspun Corp in India, and leading coils plate producer, Ternium in Mexico with the internal quality of the slabs exceeding expectations.