Piping Components: An Analysis of the Critical Dimensions

Pipe components such as elbow, tees, and weldolets are produced at various places in the world. Although the component is produced in accordance with standard ASME (American Society of Mechanical Engineers) B16.9, measurements show variation in geometry. In piping component design, the geometries are assumed as perfect in accordance with the producer’s specifications. This is a conservative approach in design that results in incorrect dimensioning of the components. Moreover, components made of duplex materials can have failure due to Hydrogen Induced Cracking (HISC) especially in subsea installations. In this article, a series of measurements were taken for ASME B16.9 long radius elbows, utilizing an ultrasonic thickness gauge. The results are compared with the nominal straight pipe dimensions in ASME. The deviation is taken as a basis for Finite Element analysis. A model of the elbow is developed using SolidWorks and simulated using ANSYS. The results compare the strength of the pipe fittings against their straight pipe counterparts with regard to internal pressure. This gives an overview of the deviations and utilization based on the measurements taken against the standard ASME B16.9 geometry