L51704 Design Guideline for High-Strength Pipe Fittings

This report presents guidelines based on the study of current practices in the design and manufacture of high-pressure pipe fittings (size tees, reducing tees, elbows, and caps) from 4 to 12 inches. Based on fitting measurements, finite-element models for linear analysis were developed and the results were compared to existing standards. The models were verified with two experimental burst tests. Tensile strength proved to be the most significant factor for burst pressure and fatigue. For fittings of unknown origin, the tensile strength can be estimated with non-destructive material hardness tests. Yield strength showed no effect on burst pressure or fatigue due to cyclical pressure loading.