New Specimen Geometry to Evaluate Structural Integrity of Pipelines from API Steel for Offshore Applications.

Abstract

Among the challenges posed by Pre-Salt exploration is the development of new materials that support the adverse conditions in ultra-deep waters and present high fracture toughness and mechanical strength. HFI-ERW (High Frequency/Eletric Resistance Welding) tubes have played a more active role in the Oil and Gas sector for deep water, high and extremely low high pressure and in highly corrosive environments, with lower operating and production costs. Once the recommendations for resistance to plastic collapse (resistance and flow limits) have been met, the knowledge and the more realistic determination of the fracture toughness of the tube being used is fundamental, particularly considering the environmental conditions to which it is submitted, in synergy with low temperature and low frequency cyclic stresses caused by sea currents. This research project focuses on a study on the achievement of the most realistic toughness values of API 5L X70 and API 5CT N80Q high strength microalloyed steels, respectively used in linepipes and pipelines for Oil and Gas applications, from data obtained with CTOD type gull-winged specimens and fatigue crack propagation on non-normalized annular specimens (new proposal). This research-work has great potential for technological production andinnovation, patenting and standardization, development and improvement of product and processes by the proponent, as well as technology transfer to the productive sector and training of specialized human resources. (AU)