More than 3,000 workers at Stanlow, Fawley, Valero, Grangemouth and Mossmorran Oil Refineries, as well as at Sellafield Nuclear Facility had voted in favour of industrial action.

But on Friday they accepted a pay deal worth more than 17.4% over two years.

The deal was secured after unions Unite and GMB balloted their members who operate under the National Agreement for the Engineering Construction Industry (NAECI) and carry out essential repair and maintenance at oil refineries, power stations and pharmaceutical and petrochemical plants.

The workers will now earn an extra 11.3% for 2024 and an additional 5.5% for 2025, along with improvements to sick pay and other allowances.

The deal is a substantial increase on the initial offer for 2024 and 2025, which was just 8.5% and 3.5% respectively.

Unite general secretary Sharon Graham said: “This outstanding deal was achieved because our members knew the NAECI employers could not ignore their demands if they acted collectively. Across the construction industry and beyond, Unite’s unrelenting focus on improving jobs, pay and conditions is winning for our members.”

Improvements to sickness and accident benefit, the London overnight supplement and the introduction of a £1 an hour London rate enhancement as well as pension, productivity and apprenticeship reviews are also included in the deal.

Unite national officer Jason Poulter said: “This excellent result is a prime example of the benefits to be gained by being part of Unite. Unite will continue to build on our industrial strength in the construction sector so we can continue winning for workers.”

Charlotte Brumpton-Childs, GMB National Officer, added: “These skilled workers have fought for the pay rise they so richly deserve.

“After watching their pay erode due to rampant inflation, they stood together and forced this whopping deal. They should be rightly proud of themselves.”