Role of hydrogen in operational degradation of pipeline steel

• DOI: 10.1016/j.prostr.2020.11.060
• Publication Date: 2020-12-01T22:16:56Z
• Authors: Hryhoriy Nykyforchyn; Oleksandr Tsyrulnyk; Olha Zvirko; Myroslava Hredil
• Keywords: Brittleness; Degradation

Long-term operation of oil and gas pipeline steels causes a significant worsening their mechanical properties, especially characteristics brittle fracture resistance. General regularities in-service degradation are analysed in the paper. Basing on these, two stages steel distinguished: deformation aging in-bulk dissipated microdamaging. Hydrogenation intensifies damaging process due to hydrogen induced microcracking and, this way, facilitates its operational degradation. In-service intensified by can cause untypical behaviour metal: a) decrease strength hardness is accompanied reducing resistance; b) an increase elongation simultaneously with reduction area. Some examples destructive role material considered, when transported hydrocarbons serve as source hydrogen. It shown that investigations extraction permeation methods provide valuable information for assessment degree. In particular, resistance good agreement concentration metal. Special attention paid rolled texture during operation. The main mechanism microdamaging textured suggested be accumulation at interface "elongated non-metallic inclusion–matrix" creating high pressure defects following microdelamination along rolling direction. This leads also anisotropy steels, which becomes more pronounced time.