The process at ExxonMobil operated Fife Ethylene Plant is scheduled to start on Monday, April 12.
Its neighbour, Fife NGL, is also shutting down and will use flares.
The down time is essential so that operators in the North Sea supply system can complete detailed inspections, servicing and upgrades as it invests in maintaining the integrity of operations.
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The company has said limited flaring will happen for around two days at Fife Ethylene Plant.
FEP’s latest community statement said: “The use of the flare for this activity is fully planned and, as part of its design function, is completely safe.”
To minimise the impact, it has taken a number of steps ahead of the stand down, and estimates it will stop its elevated flare by the end of next Monday – with the size of the flare decreasing relatively quickly during its use.
After this, it will use the ground flares for around two days.
At Fife NGL, refurbishment work is being carried out to the inlet plant from the main pipeline from St. Fergus, and its associated valves.
Some of the work will be provided by around 60 contractors.
The company plans to use its elevated flare for low volumes of ethane between April 11-15, and then the ground flares between the 15th-18th.
The ground flares are less visible during the day but can cause a glow to be seen locally at night.
Fife NGL plans to reintroduce volumes to the plant on May 6, and use its elevated flare for low volumes of ethane through next month.
This is to enable methane gas to be separated at St Fergus Gas Plant for the National Grid, and for the plant to continue the supply of propane, butane, and gasoline to thousands of customers.
Craig Burnett, plant manager, said: “We have taken steps to minimise the volume of product that must go to the flare, and it will be a tiny volume of the reduced flow into the plant.