ArcelorMittal Lázaro Cárdenas, Mexico, has recently launched production for slabs which will be used in pipelines that transport sour gas. Strengthening its position in this niche market, the Mexican site is consolidating its position as a leading producer of world-class steel slabs.
The new value added product will be used in pipelines that will 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). For this reason, best technological practices were implemented at Lázaro Cárdenas for the site to be able to produce defect-free slabs with a reduced centre segregation rate, in order to increase its share of the growing market for American Petroleum Institute pipes.
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.
