Construction and maintenance staff at the giant petrochemical complex in Grangemouth are to be balloted for strike action. Members of the GMB and Unite unions will vote on the issue along with those at seven sites across the UK.
The unions said the action followed a loss of confidence in employer's body the Engineering Construction Industry Association (ECIA). Both sides are currently involved in negotiating changes to the so-called NAECI agreement.
The National Agreement for the Engineering Construction Industry or NAECI dictates issues including pay and conditions and the use of local labour within the industry.
The ballot is due to take place from 11 August to 1 September and will take place at BP FPS Grangemouth and Ineos Grangemouth, Sellafield, Shell UK Stanlow and Staythorpe RWE, Chevron Pembroke and Aberthaw.
Unite assistant general secretary Les Bayliss said: "Unite has given employers every opportunity to come to an agreement over the union's demands, which are fair and will deliver stability within engineering construction.
"The NAECI agreement has delivered industrial peace for nearly three decades. Unfortunately, some bad employers are cherry picking the agreement or ignoring it completely."
The action follows months of industrial unrest and unofficial action at sites across the country.
Workers at the Ineos plant took part in two days of strike action which caused widespread disruption to fuel supplies in a row over pensions in April 2008.