* 24-hour strike to start at 0530 GMT
* First strike in 28 years for Unite oil workers
* Workers to stage 3-hour strikes in following weeks
* Shell expects to production impact from 3-hour strikes (Adds details, background)
LONDON, July 25 (Reuters) - A planned walkout by around 400Wood Group oil and gas maintenance workers employed atShell's North Sea platforms on Tuesday is not expectedto interrupt production from the facilities, operator Shellsaid.
The 24-hour strike action will start at 0530 GMT on Tuesdayin protest against pay cuts and tougher working conditionsenforced by oil companies due to the collapse in oil prices.
The strike will be the first staged by Unite's North Sea oilmembers in 28 years, the union said. Workers affiliated with theRMT union are also taking part.
"We don't envisage any impact in terms of productiontomorrow or later in the week," a Shell spokesman said.
The platforms affected are Brent Alpha, Bravo and Charlie,Gannet, Nelson, Curlew and Shearwater, plus Shell's Brent Deltaplatform, which is being decommissioned.
As many as 120,000 oil workers are expected to have losttheir jobs by the end of this year in an industry-wide bid tolower costs as weak oil prices have reduced profits.
Worker have already agreed to refuse to work overtime fromMonday and will also stage several three-hour strikes over thefollowing weeks.
Shell said it did not anticipate any impact on production ormaintenance schedules from these.
Wood Group said it was still trying to resolve the disputeafter senior managers visited the affected sites over theweekend. (Reporting by Karolin Schaps; Editing by Ruth Pitchford)
Wood Group (J) (WG.)
