Estudo dos mecanismos de danos de válvulas de injeção de água de poços de petróleo fabricadas em aço inoxidável AISI 316 e AISI 410

Abstract

Austenitic and martensitic stainless steels are applied in the manufacturing of water injection valves for oil exploration. Studies were performed of damage mechanisms of stainless steel AISI 316 and AISI 410 used in the manufacture of injection valves. Laboratory and field tests were performed that included: 1) installation and monitoring of field samples; 2) characterization of the injection water; 3) Samples manufacture of AISI 316 stainless steel in the annealed condition and AISI 410 under the following conditions: a) sferoidized with low hardness, b) quenched and tempered to 400 HV hardness; c) nitrided; 4) corrosion test by immersion and electrochemical to evaluate the corrosion rate; 5) erosion tests. The alloy´s characterizations were achieved by chemical analysis composition, microstructural, hardness and surface damage analysis of field samples. Results showed that the AISI 410 steel with low hardness has lower corrosion and erosion strength. The nitriding treatment increased the corrosion resistance, and quenching and tempering increased the corrosion and erosion strength of the AISI 410 alloy. The damage mechanism of the valve is predominantly corrosion. Valves manufactured on stainless steel AISI 410 are damaged by generalized corrosion after mean two months of use, while the valves manufactured in AISI 316 steel survive five months mean, and after it they experience damage by localized corrosion.