Transporting the Gas

More than 200,000 tonnes of high-grade steel pipeline will be used to bring gas from the Laggan-Tormore development to the UK mainland.

The first stage of the West of Shetland transportation network requires two 18” flowlines, each 142km long, connecting the Laggan-Tormore SPS to TOTAL’s Shetland Gas Plant, currently under construction.

Once processed, the Gas Plant will export the FUKA specification gas 234km south, via a larger 30” diameter export line –known as the SIRGE line – specifically designed with sufficient spare capacity to carry future additional production from the West of Shetland region. 

In the northern North Sea, the SIRGE line will join the existing TOTAL-operated FUKA pipeline, which currently transports gas from the Alwyn area to TOTAL’s St Fergus Gas Terminal, near Peterhead, for final processing into commercial sales gas.

Both contracts for the 18” flowlines and 30” export line were awarded to Corus in early 2010.

75% of the 18" pipelines are on the seabed, with the onshore 18" sections complete. The onshore part of the 30" export pipeline are in place, with the remainder due to be shipped out in Spring 2012.

The detailed specification requires the application of a flow coat on the inner walls of the pipe sections during milling. This coating greatly reduces friction within the pipe, helping to improve flow assurance throughout the life cycle of the transportation network. Typically, the flow coat process will see the finish of the pipeline’s inner wall reduced from a tolerance of 15-20μ (1μ = 0.001mm) to juts 5μ.

Separate contracts have been issued to Valorec Mannesman for the high carbon steel 8” monoethylene glycol (MEG) line and to Saltzgitter Mannesman International for a corrosion resistant 2” control line.

“Each contractor has been carefully chosen to ensure they meet our stringent specification criteria and provide value for money,” explains Bernie Neal, Deputy Director, Laggan-Tormore Project.

As the man responsible for overseeing the safe delivery and on time construction of the Shetland Gas Plant, subsea production system and all pipelines and umbilicals, Bernie has a clear overview of the development. “Each individual work package could be considered a sizeable project in its own right.  When you combine all the elements of Laggan-Tomore, you begin to understand the scale of the engineering jigsaw we are piecing together.”