In-Situ Vibration Monitoring of Pipeline Freespans

A wide network of subsea pipelines are in operation in the Gulf of Thailand. Due to the undulating nature of the seabed, many of these pipelines have freespans, which may be both long and high. In the past, some remedial works have been carried out to provide support to these spans to control flow induced vortex induced vibrations (VIV). However, due to the large quantity of pipeline freespans and the soft sediment of the seabed in the region, it became necessary to develop a rigorous method for prioritizing remedial works. In response to the specific difficulties encountered in this area, the operator implemented a programme of monitoring the vibrations on those spans identified as most susceptible to VIV. New equipment developed for this programme incorporated sensors for the measurement of both pipeline movement and local water velocity and a data logger to record these data. The features and development of the span monitoring equipment are described, the issues of data analysis and interpretation are discussed, and measured responses are compared with predicted.Copyright © 2008 by Jee Ltd