Decommissioning and abandonment

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Decommissioning and abandonment

Product removal

PRODUCTREMOVAL

PRODUCT REMOVAL

ƒ Remaining product displaced by water ƒ Pig train provides separation

Water

Oily water

Oil

ƒ Batch pigs

ƒ Spaced 20 m to 30 m (60 ft to 100 ft) apart ƒ Depends on diameter ƒ Number depends on line length and wall corrosion

An essential step of decommissioning is to remove the product from the pipeline. This is achieved by driving the product out with water. A train of batch pigs provides the separation between the water and the product. The batch pigs are arranged such that they are pushed by water from behind, displacing the product ahead of them. They are spaced to allow for some mixing of the liquids: typically, this is a function of the diameter of the pipeline. The number of pigs in the train depends on how much will pass each of the seals – a function of the length of the pipeline and the pitting on the pipe wall.

INHIBITION

INHIBITION

ƒ Water contains high doses of ƒ Corrosion inhibitor ƒ Oxygen scavenger ƒ Biocide ƒ Pipe left in safe condition ƒ Minimise any further deterioration or rusting