Projects - Shell Pipeline Telemetry

Tierney Strachan installs upgrades for Shell St. Fergus to Mossmorran pipeline telemetry outstations

Tierney Strachan undertook the upgrade of telemetry equipment at the 23 block valve sites on the Shell St. Fergus to Mossmorran Pipeline. The block valve sites are spaced at approximately 20 mile intervals along the length of the pipeline. Each site provides both an isolation point for the pipeline, but also provides pressure, flow and temperature data which is relayed back to St. Fergus to be analysed by a leak detection package. In the past this was done by direct British Telecom leased line.

Completed Telemetry PLC installation

Due to rising frequency of failures of the telemetry equipment, Shell sought to upgrade specific components of the system. The replacement system utilises a combination of BT Highway and ISDN lines instead of the original leased line arrangement. Through the use of programmed Cisco Router equipment, a significant cost saving is achieved, resulting in a total project payback within 18 months of installation.

At a subset of sites the Arcom I/O telemetry units were also replaced. A Schneider Momentum PLC was selected due to its compact size and that it has a native Ethernet Modbus TCP interface. The PLCs were programmed to collect a small number of digital and analogue signals, and a report by exception system was designed to reduce the number of data transfers required back to the St. Fergus system, reporting significantly changed data only.

Tierney Strachan were responsible for the design of the PLC equipment, and the installation at site (23) of replacement telemetry equipment. The PLC equipment was prepared on 19” rack mount panels for rapid deployment at site. A companion PLC was installed at the St. Fergus site to interface to the pipeline leak detection system.