DURABILITY OF THE OIL PIPELINE SYSTEMS UNDER ENVIRONMENTAL EFFECTS

Abstract

Recent discoveries of petroleum and gas reserves in environments with severe operationalconditions metallic materials, carbon and low alloy steels, have pushed and prompted theneed to find alternatives. The presence of gaseous hydrogen may cause the suffering ofhydrogen damage and embrittlement. The effect of hydrogen and temperature on fatigue lifeproperties, have pushed the utilization of steel procurement specification even stricter thanthey used to be. The main modifications concern the mechanical resistance, toughness at lowtemperatures weld ability and resistance to embrittlement related to hydrogen.Aiming to enhance the reliability and operation of pipelines system, a study based on theelastoplastic 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 testedhere are API 5L X70 and X100 micro alloyed steels. Hydrogen had affecting the materialproperties, which are reducing the toughness and an influence spotted in Charpy tests.