The Turk Stream is the first gas pipeline with a diameter of 81 centimetres to be laid at depths exceeding two kilometres. It starts on the Russian coast near the town of Anapa and runs over 930 kilometres through the Black Sea to come ashore in Kiyikoy, Turkey. When operational, Turk Stream will offer a reliable energy supply for Turkey and Europe by delivering 31.5 billion cubic meters of natural gas annually.
The offshore component of the system consists of two parallel pipelines; each made up of individual pipe sections of 12 meters in length. The pipes have been made from specially designed carbon manganese steel plates to withstand the huge pressure under the sea. Pipes laid in shallow waters closer to the shore have been coated in concrete for added stability and protection. The biggest construction vessel in the world, Pioneering Spirit, carried out the offshore construction with the pipe joints welded to each other and to the main string on board. Each weld was tested and coated for protection before the pipeline string was lowered into the water. Pioneering Spirit has completed the construction in just over 15 months. Operating around the clock, the vessel laid 5 kilometres of pipeline on average each day. Once completed the pipeline needed to be cleaned and inspected internally, using several Pipe Inspection Gauges, known as PIG’s. A PIG can be used to inspect and/or clean the pipe. The PIG’s are inserted into a launching station and propelled through the pipeline using compressed air generated by a compressor spread. Throughout its journey the PIG records data on the condition of the pipe interior.
Baker Hughes Process and Pipeline Services were contracted for the Turk Stream pipeline pig operations. They approached Flowquip, the UK’s leading provider of flow meters and process control solutions, to design and supply a compressed Air and Nitrogen flow measurement control solution. Flowquip delivered a solution that incorporated two DN250 (10”) Vortex Flowmeters, one 10” V-ball pneumatic control valve, Pressure, Temperature, Differential Pressure and Oxygen transmitters and a Control Panel. The control panel incorporated two Contrec 515 Flow Computers, one Siemens PLC, one Red-lion HMI, one GSM Internet Gateway, UPS power backup system and control valve override switch/controller. Offering tried and tested accurate flow technology in the field Vortex flowmeters were selected for their simplicity and robustness; this was a task for which reliability was paramount. During Pigging operations, the system used signals from one set of instruments but could be switched over to the second set in the event of a component failure or other measuring related issue. This bespoke measurement and control package was designed to accurately measure the volume and mass flow of air, pressure and temperature through both pipe work systems. It also provided auto PID control of the pneumatically actuated 10″ V-ball valve to govern the speed of the pig train based on the calculated mass flow rate of air and monitored differential pressure across downstream air filters. In addition all the data was logged for the complete pigging operations locally in the HMI and securely to the Cloud. To ensure safe and effective completion of the Pigging operation it provided local visual system alarms and remote e-mail alarms to specified users; it also supplied back-up power to all instrumentation and control valves for 60 minutes in the event of site main power loss. As an additional safety feature it also provided local manual override of control valve positions and local emergency shutdown of the valve. It allowed for auto PID control for final air venting of pipe lines based on downstream system pressure and monitored oxygen content of air to determine arrival of nitrogen gas packing. And finally it allowed authorised remote access to PLC and HMI programs to enable Flowquip engineers to carry out system modifications on-the-fly. Flowquip has successfully designed and supplied a complete and bespoke compressed air and nitrogen flow measurement control solution for Turk Stream. This solution operated in a challenging environment, as part of a ground-breaking international project that has advanced the technical boundaries of the gas pipeline industry.
For more information on Flowquip’s flow control solutions, call us on 01422 829920 or email sales@flowquip.co.uk
