Numerical study of semi-elliptical cracks in the critical position of pipe elbow

Abstract

Pipelines are considered as a major tool to transport hydrocarbons due to its important role in transporting fluids taking into account the operating conditions. Despite the importance of the elbow which considered as a critical part in the pipelines, the repeated failures and defects became a dangerous and enormously costly issue. In this numerical study, the Fluid-Structure Interaction (FSI) analysis was carried out using Ansys software. This work is divided into four main parts: the first part focused on studying and comparing the effect of bending radius of pipe elbow on the maximum of Von-Mises stress values for each radius with the yield stress of the steel of the pipe. The second part focused on the creation of a semielliptical crack for different locations along the elbow angles to show the critical position compared to the stress intensity factors. In the third part, the Citation: Muthanna, B. G. N., Bouledroua, O., Meriem-Benziane, M., Hadj Meliani, M.,

Assessment of corroded API 5L X52 pipe elbow using a modified failure assessment diagram

“…t h e i ntr a d os of t h e pi p e el b o w. somewhat higher than the critical semi-elliptical relative crack depth ratio (d/t= 0.28) in the pipe elbow obtained in our previous study [12].…”

“…The obtained critical depth ratio (d/t= 0.69) of the rectangular parallelepiped-shaped corrosion defect with rounded corners for the straight pipe, Fig. 8, is slightly higher than for the critical semi-elliptical relative crack depth ratio (d/t= 0.66) in the straight pipe obtained in our previous study [12]. Also, for the crack depth ratios lower than the critical (0.1 < d/t 0.66), investigated in our previous study [12], all assessment points were located in the more dangerous elasto-plastic fracture domain of the NFAD.…”

“…8, is slightly higher than for the critical semi-elliptical relative crack depth ratio (d/t= 0.66) in the straight pipe obtained in our previous study [12]. Also, for the crack depth ratios lower than the critical (0.1 < d/t 0.66), investigated in our previous study [12], all assessment points were located in the more dangerous elasto-plastic fracture domain of the NFAD. Contrary, in this study of the rectangular parallelepiped-shaped corrosion defects with rounded corners in the straight pipe, for all defect depth ratios lower than the critical (0.1 < d/t 0.69), the assessment points are located in the less dangerous plastic collapse fracture domain of the NFAD, as shown in Fig.…”

“…This complicated network of pipelines includes the necessity for usage of numerous and various pipe elbows (bends) and junctions for distribution, transportation, and change of the fluid direction. The pipe elbows are prone to the various damage mechanisms on both internal and external surfaces due to the exposure to fluids and external environments such as corrosion, erosion, erosion-corrosion fatigue, and different other combined damages [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Frequently this leads to the burst in critical parts of piping systems, forced outages, and long term interruptions in operation.…”

Modeling the Repair of a Crack in an HDPE Pipe

“…Since damage is the main cause of crack growth, some researchers have focused on failures and risks associated with HDPE pipe used for trenchless rehabilitation and new construction technologies [5,6]. Others have studied the breakage of the HDPE material [7][8][9][10][11][12].…”