Effects of Ultrasonic Flowmeter Internal Diameter Differences on the OSBRA Pipeline Measurement Results

The objective of this paper is to describe the effect of the differences between the pipe and the ultrasonic flowmeter internal diameters on the flow-rate measurement results, and to compare the values found with the differences on the pipe balance. The work included field analysis, numerical simulation and meter calibration. The ultrasonic meter balance differences were the reason for this research. The field analysis presents the balance and internal diameter differences. The numerical simulations comprise one, two and three-path meters with arrangements similar to the OSBRA meters. Three flowmeters were calibrated with water and different internal diameter meter runs. The results of the calibrations were compared with the results of the simulations, and also a comparison was made between the simulations and the actual field measurements. The conclusion is that internal diameter differences may generate differences in the ultrasonic flowmeter result, but the differences expected for OSBRA flowmeter results were less than 0.5% which is significantly less than the observed balance differences.