Wood Group said it “respected” the right of offshore staff to take industrial action on the eve of strike action in the North Sea.
The company has been in prolonged talks with workers over changes to pay and conditions.
The move, which will impact staff working on Shell assets, led to a ballot by both Unite and RMT workers earlier this month.
Oil major Shell has already said it does not expect the strike action to impact production.
Most Wood Group staff work on maintenance while production staff on the assets are Shell employees who are not through to be involved with the industrial dispute.
An overtime ban has already started ahead of strike action tomorrow.
One worker told Energy Voice the changes to his contract would impact his salary by up to £20,000.
It’s understood some of the changes in dispute between employees and Wood Group are to salary structure which includes “inclusive payments”.
There were payments for overtime, nightshift, Christmas and New Year paid regardless of what was actually worked by staff member.
Dave Stewart, chief executive for Wood Group’s eastern region business unit, said: “Our employees’ safety and wellbeing remains our top priority and our commitment is to ensuring it is not compromised during industrial action. Although we are extremely disappointed that industrial action will be taken, we respect the right of those employees who choose to do so.
“Our firm focus remains on reaching a resolution, which meets our mutual goal of sustaining these jobs for our employees in the North Sea now and in the future, against the backdrop of an extremely challenging climate created by the sustained low oil price.
“We are continuing to engage frequently, proactively and openly with our employees and the unions. We met with union representatives on Friday and senior management have visited impacted installations over the weekend to talk with our people, with the clear aim of positively progressing discussions towards reaching a resolution.”