Abstract: An apparatus and method for heating hollow bolts (20) mounted in aligned openings (18) of a pair of members (10,12) to be connected together. A conduit (42) supported by a cylindrical body (40) from the end (29) of the bolt (20) is inserted within the bore (34) of the bolt (20). A fired stream of heated fluid from a gas torch (90) flows through the conduit (42) thereby to heat the bolt (20) for providing sufficient elongation for predetermined tightening or loosening of the associated nut (30). One embodiment (FIG. 1) utilizes a hollow bolt having a blind end central bore (34). Another embodiment (FIG. 3) utilizes a hollow bolt (26A) having a central bore (34A) extending through the entire length of the bolt (26A).