Fracture Toughness Testing Using SENT Specimens in a Sour Environment

Abstract

Offshore pipelines and risers constructed from carbon steel have reduced levels of performance when operating in a sour environment. Fatigue crack growth rates can be significantly higher and material fracture toughness may be significantly lower. In this paper a fracture toughness test procedure for the pipeline girth weld in a sour environment is introduced. The single edge notched tensile (SENT) specimen, which has been widely accepted for the pipeline girth weld fracture toughness tests, was used in this proposed procedure. As expected it was found that the fracture toughness of the girth weld was reduced significantly after exposure to simulated sour service (NACE solution A), and this result is used for the assessment of the weld root defects that may work in the sour environment.

Effects of Strain Rate on Fracture Toughness in Sour Environment

“…The methodology of testing and application of the fracture toughness value for ECAs of pipeline girth welds for sour service has been presented in a previous OMEA conference (paper OMEA2009-79305 (1) ). During the course of the previous study, the effect of strain rate on the fracture toughness testing result was observed.…”