* 24-hour strike on seven Shell platforms set for July 26
* To be followed by three-hour strikes in coming weeks
* Maintenance workers strike may not impact production
* Shell making contingency plans to ensure safety - source (Updates throughout)
By Karolin Schaps
LONDON, July 18 (Reuters) - A 24-hour strike of Wood Group oil and gas maintenance workers will "severely disrupt"operations at several Royal Dutch Shell platforms inthe North Sea where they are employed, labour union Unite saidon Monday.
The strike action scheduled for July 26 will be the firstwalkout by UK North Sea workers in ten years as oil and gasstaff are angered by pay cuts and tougher working schedulesbrought on by cost savings amid the oil price crash.
The workers will also undertake several three-hour strikesover the following weeks, a union representative said.
At total of seven Shell platforms, including the historicBrent facility, will be affected by the strike of Wood Groupemployees who carry out maintenance. This means production fromthe platforms may not necessarily be impacted.
Shell is making contingency arrangements to ensure safety isnot affected by the strike action, a person at the company said.
"It is anticipated that the action will severely disruptoperations on the Shell platforms," the union said in astatement.
The platforms affected are Brent Alpha, Bravo and Charlie,Gannet, Nelson, Curlew and Shearwater. Shell's Brent Deltaplatform, which is being decommissioned, is also included.
An overwhelming number of employees backed strike action ina ballot carried out last week.
Wood Group said it was continuing to engage with employeesand labour unions to reach a resolution.
Shell said it hoped Wood Group and its employees would cometo an agreement. (Editing by David Clarke and Mark Potter)