The US$250 million (£199 million) deal sees Ineos take control of a system that delivers almost 40% of the UK's North Sea oil and gas.
The 235 mile pipeline system links 85 North Sea oil and gas assets to the mainland and the Ineos site in Grangemouth.
The acquisition also includes the Kinneil Terminal.
About 300 staff will transfer to Ineos FPS Limited, a newly-formed business that will be part of Ineos Limited.
Chief executive of Ineos FPS, Andrew Gardner, said it was a "very significant deal" for the company.
"The acquisition reunites North Sea and Grangemouth assets under Ineos ownership," he said.
"Ineos is now the only UK company with refinery and petrochemical assets directly integrated into the North Sea and this deal provides the platform to potential future offshore Ineos investments."
The Forties pipeline was opened in 1975 to transport oil from BP's Forties field. Today, the pipeline system has an average throughput of around 445 000 bpd of oil.
Under the terms of the deal announced in April, Ineos was to pay BP US$125 million (£99.5 million) on completion and an earn-out arrangement over seven years that totals up to a further US$125 million.
The completion of the deal has strengthened the company’s standing as the largest privately owned exploration and production business operating in the energy basin.
Read the article online at: https://www.worldpipelines.com/business-news/01112017/ineos-completes-acquisition-of-forties-pipeline-system/