Influencia del tamaño de las discontinuidades en las propiedades mecánicas de las uniones soldadas bajo la Norma API 1104

Abstract

In this research, the effect of discontinuities mentioned in the API 1104 standard about the mechanical properties of standard test pieces were evaluated. For this purpose, test specimens were obtained with different sizes of defects and those were characterized with the API1104 standard. The obtaining of various defects was performed by metallic inclusions, non-metallic inclusions or machining, depending on the type of discontinuities. The dimensions of external discontinuities were checked by visual inspection, while internal defects were checked through industrial radiography. Due to the difficulty in manufacturing certain sizes of discontinuities, the analysis was completed using simulations with ANSYS 16.1 software. The simulation results were validated with the data obtained from the mechanical tests of standard test specimens. From this comparison, errors of less than 5% were obtained in all cases. From the results obtained it is seen that all sizes of defects have an inversely proportional behavior compared to the tensile strength. According to the API 1104 standard, the most critical defects are the cracks, and the present research confirms that. Following the cracks, in order of criticality we have the inadequate penetration, elongated slag inclusion, incomplete fusion and incomplete fusion due cold lap. Subsequently, the isolated slag inclusions are in conjunction with the pores. Then, the inadequate cross penetration with the undercutting. And finally, the rest of discontinuities as inadequate penetration due high-low, internal concavity and burn-trough.