Lateral and Transverse Stiffness Requirements for Supports of Pipeline Systems Conveying Fluids

Abstract

Elevated pipelines systems are commonly supported by flexible steel frames at regular intervals. During operation, these systems can be subjected to sources of harmonic excitations. In order to control the vibration response for such systems, designers may target a threshold minimum fundamental natural frequency for the system. Within this context, the study first shows that, within the ranges of straight pipelines geometries commonly used in the oil and gas industry, the fluid mass and stiffness of the intermediate flexible supports significantly impact the fundamental natural frequency of the system, while fluid velocity within the practical range of the oil and gas industry, temperature differential between the installation and operating temperatures, and pipe self-weight are less important or negligible. The study further extends the analysis to nonstraight piping systems with L-Shape and S-Shape configurations. In conclusion, design formulas are proposed to estimate the required lateral and transverse stiffnesses for the supporting systems to attain a specified fundamental natural frequency for straight and curved pipelines. Natural frequency comparisons with finite element solutions show the validity of the proposed design formulas.