Abstract

Transient surge pressures of a system with parallel pipes are dependent on the simulation setup of the check valve closing times installed on the parallel pipes. Applying an identical closing time for the parallel check valves can create different surge pressures due to uneven flow distribution through parallel lines during surge transient events in a transient hydraulic simulation. Four methods for check valve closing time were investigated for the parallel pipes included in the simulation scope. The first method is to apply check valve closing time based on rule of thumb for all check valves included in the simulation. The second method is to apply check valve travel time based on the check valve’s dynamic characteristic curve and the transient characteristics of the system [1]. The third method is to apply the check valve travel time based on the check valve’s dynamic characteristic curve, the transient characteristics of the system, the critical velocity, and the cracking pressure of the check valves included in the simulation. The fourth method is to apply dynamic closing time for the check valves included in the simulation. The dynamic closing time is calculated based on the check valve’s dynamic characteristic curve and the transient characteristics of the system. The calculated check valve closing times are applied to all check valves dynamically and are updated for each transient wave approaching the check valves and causing them to start closing.

The purpose of this paper is to present the simulation results of the maximum surge pressure in the parallel piping with the different methodologies applied to the closing time of the check valves installed in the parallel paths. The result of this simulation is applicable to surge analysis of an oil terminal with parallel piping associated in the study flow paths.

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