Fatigue Analysis of a Longitudinally Oriented Ellipsoidal Crack in the ERW of ASTM A53 Type E Gr B Carbon Steel Pipe in a Lithium Process Plant

The main goal of this approach is to present a technical analysis based on fracture mechanics theory, examining the fatigue behaviour of a simulated longitudinal crack with an ellipsoidal geometry in a firewater pipeline belonging to a process plant designed under the ASME B31.3 Process Piping Design Code for processing lithium ore in northern Argentina. The study focuses on a straight section of carbon steel piping (ASTM A53 Type E Gr B) with a diameter of 20 inches, simulating a longitudinal crack with an ellipsoidal base induced in the upper part of the forging area. This is under pressure design conditions of ±1.30 MPa (σ m Mean Stress = 0) and a constant temperature of 60 °C, according to the design specifications of the lithium extraction project A1C. This approach uses the strain-life fatigue analysis method available in the Ansys fatigue module. Strain-life is usually concerned with crack initiation. This procedure uses a numerical simulation method in the ANSYS 2025 R1 workbench. The results show that the lowest fatigue life occurs in the FWZ (Forged Weld Zone) area of the ERW. Once the obtained values have been analysed, the critical zones of the crack and low cycling are identified. It is suggested that pressure should be kept below the critical value, and that experimental studies available in literature should be carried out to compare the results of this approach. These conclusions form the basis for applied research in real case studies in industry.