The owner of the Grangemouth plant is expected to announce whether it will reverse a shock decision to close the site, safeguarding hundreds of jobs.
Ineos has been discussing a change in position by the Unite union whose members now say they will commit to a plan aimed at securing its future.
The petrochemicals plant and adjoining oil refinery making up Scotland's largest industrial complex was shut down last week in advance of a planned walkout over pay and conditions.
Ineos did not restart the site after Unite called off the strike but wrote to staff asking them to sign up to changes such as a pay freeze and the closure of the final salary pension.
The company insisted on Wednesday it had no alternative but to close the plant after it failed to persuade its staff to accept the survival plan but Unite general secretary Len McCluskey said yesterday the union would embrace it "warts and all".