Dissertação
Inertização de minerodutos para mitigação de sua corrosão interna
Fecha
2021-02-24Autor
Ayron Silva Guimarães Torres
Institución
Resumen
The transport capacity of the pipelines is related to the internal roughness of the
pipeline. Thus, the application of corrosion protection methods is of fundamental
importance, both in the operational phase and in times of temporary shutdown.
In addition, corrosion also affects the life of the pipeline. The second Samarco’s
slurry pipeline was inertized with nitrogen gas in 2015, using the ABNT NBR
15280-2 standard as reference. Chemical, mineralogical and microstructural
analyzes were conducted on samples of materials removed from the inside of the
duct by foam pigs, in 2017, in order to identify and characterize the corrosion
product. The most striking phase found was magnetite, with botrioidal
morphology, formed by the oxidation of steel in the pipeline. In 2019, the slurry
pipeline was reactivated and later inspected with smart pigs, ultrasound and MFL
(Magnetic Flux Leakage) technologies. In these inspections it was found that the
corroded regions are more concentrated in the initial kilometers of the sections,
where greater depths of corrosion were also observed, as well as higher
corrosion and erosion rates, which shows the greater influence of the operational
phase in the development of the corrosive process and pipeline wear.
Furthermore, most of the corroded regions reported by the pig have a low
percentage of depth, varying between 10% and 33%, with more than 98% of
these regions having depths less than or equal to 15%, which shows that the
corrosive process is not developed substantially. Thus, the application of the
inertization process in long-distance pipelines proved to be feasible for long
periods of time. However, this work suggests improvements in the inertization
process to make it more robust.