* Refinery outage could cause disruption to Forties grade
* Strike prompted by alleged victimisation of worker
* Decision to be made by union on Monday or Tuesday
By Simon Falush
LONDON, Sept 27 (Reuters) - Workers at the 210,000 barrel-per-day (bpd) oil refinery in Grangemouth, Scotland voted on Friday in favour of strike action, raising fears of disruption to North Sea oil supplies that could drive up the benchmark oil price.
Steam from the Grangemouth refinery, owned by PetroIneos , powers the adjoining Kinneil terminal, which receives oil from a pipeline carrying North Sea Forties, one of the four crudes that underpins the Brent oil benchmark.
"It could be very bullish for Brent...due to the Kinneil tie-up with the refinery," one trader said.
A strike at the refinery in 2008 led to concerns about oil supplies and queues at petrol stations around Scotland as well as pushing gasoil futures to a record high.
Brent oil rose following the news on Friday, reversing direction from a fall earlier in the day.
Over 80 percent of the workers balloted voted in favour of strike action over operator Ineos's treatment of a union organiser and worker, Stephen Deans, who is at the centre of a disciplinary action, the union said on Friday.
A decision on the next steps for industrial action would be taken will be made after the weekend, Pat Rafferty, Scotland's Regional Secretary told Reuters.
"We've clearly got a strong mandate. We're consulting with out shop stewards and will notify the company on Monday or Tuesday."
Ineos is investigating Deans over whether his political activities with the Labour Party contravened company policy, and accuses the union of interfering with its inquiry.
"Ineos will not be bullied by the union's behaviour. There cannot be one rule for union officials and one rule for everyone else," said Calum MacLean, chairman of Ineos Petrochemicals UK.
Ineos said that the investigation into Deans will be completed by Oct. 25.
The Forties pipeline was expected to load about 329,000 bpd in October.
A spokeswoman for BP, which operates Kinneil, confirmed that it relies on steam from Grangemouth but said she could not comment on the impact of a possible strike.
Relations between the workforce and Ineos, already strained by the investigation into Deans, were put under further pressure after comments about the future of the chemical plant.
MacLean said last week the plant could close by 2017 unless it cuts pension costs and got government support.