Comportamento à fadiga de juntas soldadas de tubulações marítimas tratadas pela técnica TIG Dressing.

Abstract

Due to cyclic loads, steel catenary risers are subject to fracture risk by fatigue, mainly in the girth welds disposed along of their length. Depending on the alignment and the weld root conditions, such joints, made from the outside only because of the small diameter of tubes, may have very poor fatigue strength. By a remelting pass without filler metal, geometric discontinuities and defects could be removed and a improvement in fatigue strength could be achieved. Under these aspects, this work evaluated the possibility of the TIG dressing technique be used internally in the weld root of risers, by testing welded joints of these pipelines in as-welded and TIG dressed conditions. The results showed significant increases of the stress levels and of the fatigue life for the TIG dressed specimens when compared with as-welded condition These increases demonstrated that welds made by Shielded Metal Arc Welding Process and modified in the weld root by remelting treatment can be designated as Class E, superior to Class F2, as actually they are designated by project codes.