Large-diameter buried water pipes are crucial components of modern urban infrastructure, and their consistent performance is vital for maintaining the resilience of our cities. The American Water Works Association's Manual of Water Supply Practices M11, Steel Pipe—A Guideline for Design and Installation, provides details for fittings design, appurtenances, and miscellaneous details. While the guideline provides details for the design of collar plates, crotch plates, and miter bends, no guidance is provided for stress intensity factors (SIFs) required for thermal stress analysis of these aforementioned components. Furthermore, in the oil and gas industry, SIFs are provided in different codes and standards; however, those SIFs are not applicable for large diameter, relatively thin-walled pipes (i.e., D/t > 100). In this study, finite element (FE) analyses are conducted to assess the design model for tees and miter bends proposed by the American Water Works Association. For reference, a linear-elastic analysis is first conducted for a large-diameter tee without reinforcement to compare results with the ASME B31J guideline. Subsequently, the effect of the reinforcement and large diameter is also investigated. The reinforcement of the tee has a positive impact on component SIFs, although these reinforcements are provided mainly to compensate for the material removed due to branch (outlet) installation.
Muntakim et al. (Thu,) studied this question.