Workers at Heerema, a rig-building plant in Hartlepool, are set to start an indefinite strike this week over pay.
The strike, by 130 workers in the Amicus and GMB unions, is set to take place from Friday.
The strike will involve pipe-fitters, welders and platers.
A ballot last week saw workers vote overwhelmingly in favour of industrial action.
A final offer from the management of a 3.5 percent rise this year and a similar increase in 2008 was rejected by the workers.
Jimmy Skivington of the GMB said, “The final offer was made in January, and it was rejected unanimously by our members. After a meeting last Friday it was decided that industrial action will be taken and continue until we have a settlement.”