Fracture analysis of hydrogen-embrittled API X52 pipes at low temperature

•The effect of temperature on fracture toughness for hydrogen-embrittled API X52 is quantified by combining small punch (SP) test data and finite element (FE) analysis.•A procedure for fracture toughness prediction in hydrogen at low temperatures is presented using coupled hydrogen diffusion analysis.•Hydrogen-embrittlement constant is determined by analyzing SP test in hydrogen at low temperature for simulating hydrogen-enhanced ductile fracture.•The effect of temperature on the maximum pressure of cracked pipes in hydrogen is analyzed using fracture mechanics analysis.•It was found that the effect of temperature on the maximum pressure would not be significant. This paper quantifies the effect of temperature (ranging from room temperature (RT) to -90 °C) on fracture toughness for hydrogen-embrittled API X52 by combining small punch (SP) test data and finite element (FE) damage analysis. For the FE damage analysis, a multi-axial fracture strain damage model was used, and the parameters were determined by analyzing the tensile and SEN(T) test data in air at RT. The hydrogen-enhanced ductile fracture was considered using the hydrogen-embrittlement constant, which was determined by analyzing the SP test results in hydrogen. Due to the effect of the interaction between strength and hydrogen-induced ductility loss on fracture toughness, the predicted fracture toughness in terms of temperature does not show a monotonic decrease up to -90 °C; rather, it decreases up to -30 °C, then increases slightly before decreasing again. Fracture mechanics analysis of a hydrogen-embrittled pipe with an axial surface crack using the determined fracture toughness values showed that the maximum pressure decreased slightly (less than 9 %) with decreasing temperature up to -90 °C, suggesting that the effect of temperature on the maximum pressure would not be so significant for API X52. Fracture Analysis of Hydrogen-Embrittled API X52 Pipes at Low Temperature Using SP test data at low temperatures in H2 and fracture mechanics analysis, it was found that the effect of temperature on the fracture of hydrogen-embrittled API X52 would not be significant. [Display omitted]