A project to lay the major part of the world’s longest undersea pipeline has been designed and executed by IGAS Technology Solutions. This was undertaken through Dominion Technology Gases – who provide the system package and welding gases to Stolt Offshore’s LB200, one of the world’s largest pipe-laying vessels, as it works on the 1200 kilometre Langeled gas pipeline.

Stolt Offshore will construct and lay about 890km of the pipeline from Norway to the UK, completing 525km this year and 360km in 2006. The challenge was to supply a moving vessel with a system tailor-made to meet the demands of a rigorous schedule and exacting conditions.

The requirements of the project were to build a system to deliver propane, used for pre-heating the pipe, to 40 user points on the barge. The ability to blend argon and carbon dioxide into an 80/20 mix for repair work and a 50/50 mix for pipeline construction on board the vessel, and lastly, to provide a system to deliver the welding gas to six welding supply stations around the barge.

Dominion’s 300 bar Quad packages reduce the number of offshore lifts and cuts shipping, transport and rental costs by up to 40%.

The unique gas-mixing system to blend the argon and carbon dioxide on board the vessel, helped reduce the number of offshore lifts as pre-mixed welding gas is too unstable to transport at higher than 90 bar pressure and supplying it would have increased the turnover of cylinders almost tenfold.

Containerised Mixing System///Image courtesy of IGAS Technology

The project was completed and commissioned within nine weeks of order, with the installation of over 1.2km of pipework for the propane system in two weeks, and the installation and commissioning of the gas mixing system, including 800 metres of supply header on board in three weeks.

The Langeled pipeline will run from the Ormen Lange gas field, 120km west of Norway, via Nyhamna and the Sleipner area, through to Easington on the south- east coast of England. The field is expected to meet 20% of the UK’s gas demand for up to 40 years.

For further information:
iGas Technology Solutions
Dominion Technology Gases
Sholt Offshore