Hundreds of North Sea workers are set to take part in a fresh wave of strike action in an ongoing pay row.
Unite said about 600 workers at Bilfinger UK had turned down a new offer, and announced planned strike dates for next month.
The union said two 48-hour strikes were expected to take place on 1-3 June and 8-10 June.
Bilfinger said it would continue to engage in talks in a bid to reach a resolution.
Unite told the BBC that said a new offer was rejected by members based on assets of operators Ithaca, CNRI and Taqa.
Unite general secretary Sharon Graham said: "Unite's offshore members working for Bilfinger have given a loud and clear answer to the company and oil operators."
In a statement, Bilfinger said: "We respect the right for peaceful and planned strike action and will continue to engage with the unions, our clients and our colleagues to come to a positive resolution.
"Operational safety remains our top priority and we have procedures in place to minimise any potential disruption."