Systems resume at the Grangemouth oil refinery
The gradual process of resuming production at the Grangemouth oil refinery has begun following a 48-hour walkout by staff at the plant.
Refinery operator Ineos said it could take between two and three weeks before its systems were running to pre-strike levels.
The 1,700-acre site normally produces nine million litres of clean fuel a day, processing 210,000 barrels of oil.
In addition, two million tonnes of chemicals are processed every year.
In order to shut down the site safely, each plant, whether it processed diesel, petrol or chemicals, had to be cooled and depressurised gradually over a series of days.
The same is true for resuming production.
A spokesman for Ineos said the oil refined at Grangemouth was sent to various plants across the site for processing in order to produce fuel or plastics like polyethylene.
Each of these plants operate at different temperatures and rely on interconnecting streams from adjacent sites which feed into them.
The spokesman said it was difficult to predict exactly how long the process would take, but a phased start-up programme had begun.
He said: "We have never been in this place before. Of course certain plants have been shut down for maintenance but the whole site has never been shut down at once.
"We estimate it will be about two to three weeks before we get things back to full production.
"We are dealing with complex machinery which needs to be restarted safely."
BP said it anticipated that the Forties Pipeline System (FPS) would be back at 100% capacity in "several days".
The pipeline delivers about 700,000 barrels of oil and 80 million cubic metres of gas a day to the mainland.
Crude oil is pumped to BP's Kinneil plant near Grangemouth and relies on the Ineos site for power and steam.
Workers at Grangemouth agreed to feed a "minimal" amount of power and steam to the Kinneil plant during the strike in order to ensure a quicker start-up of the system.
The pipeline feeds oil to the plant from 70 North Sea oil fields.
A spokesman for BP said: "We received confirmation that the critical utilities we need are once again available.
"We've now started the process of getting the pipeline back up and running.
"Although the Forties system can be operational within 24 hours, it will take the offshore fields some time to get back up to capacity.
"We estimate that this process will take several days, beginning with low levels of oil before it gradually ramps up."