FLAGS

The FLAGS (Far North Liquids and Associated Gas System) pipeline is a natural gas pipeline in the North Sea which is used to transport liquids and associated gas from the following fields:

• Cormorant A
• North Cormorant
• North West Hutton
• Ninian Central
• Ninian North & South
• Brent 'A', 'B', 'C' and 'D'
• Tern
• Magnus
• Thistle
• Murchison
• Statfjord
• Heather
• Gjøa
• Gas exported from West of shetland oil fields (Foinaven, Schiehallion/Loyal and Clair)
• Knarr

The pipeline is a 36-inch (910 mm) steel pipe to API 5L, X60 specification and is 450.6 kilometres (280.0 mi) long. It starts at Brent 'A' and terminates at St. Fergus near Peterhead in Scotland.^[1] Pipe laying was completed in April 1978 and finally commissioned in May 1982. The pipeline was laid by SEMAC 1.

At Brent A, the pipeline is connected with the Northern Leg and Western Leg transmission systems, carrying gas from a number of nearby fields.^[1] The 20-inch Northern Leg Gas Pipeline (NLGP) runs for 80 km from Magnus to Brent A with spurs to Thistle A, Murchison and Statfjord B. It originally served as the gas export route for these installations and delivered gas to Brent A for onward transmission to St Fergus via FLAGS. As some of these installation have become gas deficient it has served as their gas supply route. The pipeline has depressurisation facilities at Magnus. Gas from the NLGP is heated before flowing via manual pressure let-down valves to the HP and LP flare systems. Pre-heating the gas ensures that it remains within the temperature limits of the flare pipework after Joule-Thomson cooling across the let-down valves.

Natural gas from the Norwegian Statfjord field is fed through the Tampen pipeline, linking Norwegian and UK gas trunkline networks.^[2]

References