DURABILITY OF THE OIL PIPELINE SYSTEMS UNDER ENVIRONMENTAL EFFECTS

Abstract

Recent discoveries of petroleum and gas reserves in environments with severe operational
conditions metallic materials, carbon and low alloy steels, have pushed and prompted the
need to find alternatives. The presence of gaseous hydrogen may cause the suffering of
hydrogen damage and embrittlement. The effect of hydrogen and temperature on fatigue life
properties, have pushed the utilization of steel procurement specification even stricter than
they used to be. The main modifications concern the mechanical resistance, toughness at low
temperatures weld ability and resistance to embrittlement related to hydrogen.
Aiming to enhance the reliability and operation of pipelines system, a study based on the
elastoplastic fracture was carried out to determine high level prediction for the fatigue life,
as well as to evidence the toughness resistance of the used materials. The materials tested
here are API 5L X70 and X100 micro alloyed steels. Hydrogen had affecting the material
properties, which are reducing the toughness and an influence spotted in Charpy tests.