PURPOSE: To provide a method for hydraulically prestressing bolts of a turbine casing or the like and to provide an apparatus for implementing this method.

CONSTITUTION: A method for prestressing bolts arranged in places where lateral accessibility is reduced, particularly casing bolts for turbines, is disclosed. This method comprises steps of mounting a bridge element 41 on end faces of threaded ends of support bolts 21, 23 positioned at either side of a bolt 22 selected for prestressing; and prestressing the bolt 22 by means of hydraulic stressing means 42, 45 arranged in the bridge element 41. Also an apparatus for carrying out this method comprises a bridge element 41, a pulling sleeve 42 with hydraulic drive means 45 arranged on the bridge element, and means for generation of hydraulic pressure.