Análisis estructural de tuberías de oleoductos abolladas por carga explosiva

Abstract

This paper presents the broad experience obtained in the Caño Limón Coveñas pipeline (OCLC), located in Colombia, on the manipulation and evaluation of the dents caused by explosive charges. During the last ten years, the OCLC pipeline has suffered more than 450 terrorist attacks using explosive charges. Most of the damages do not cause the total rupture of the pipes, they only generate dents and distortions grater than five percent (5%). A as consequence of this situation, we have tried to acquire all the judgement elements required to choose the appropriate time to change the pipes an to know the pressure level for a continuos and safe operation of the pipeline. The study include some three main aspects: (a) Characterization of the dents considering their geometry, materials (hardness, metallographic structure, efforts, etc) influences of explosive charges and of the operation pressure as well as hydrostatic pressure tests overa real scale pipe, (b) Creation and validation of a new method for dent evaluation and (c) Discussion of the analysis through numeric modeling. Results show an increase in the elastic and rupture resistance of the material located in the target area and therefore, a subsequuent fatigue resistance decrease. Fatigue is the possible cause for the subsequent rupture of the pipeline once it has been dented by an explosive charge. The hidrostatic tests have shown that a partial shape recovery is obtained when the pipeline undergoes a high operational pressure. For a 24% dent there will be 0.036 m recovery at a 1 2.4 Mpa pressure.