The ornamental design for a hinge element for roofanchor, as shown and described.
FIG. 1 is a perspective view of the hinge element for roof anchor;
FIG. 2 is a front view thereof; the rear view is a mirror image;
FIG. 3 is a left side view thereof; the right side view is a mirror image;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof; and,
FIG. 6 is an environmental perspective view of the hinge element for roof anchor.
The broken lines in the drawings illustrate portions of the hinge element for roof anchor and form no part of the claimed design. The broken lines showing of the roof anchor in FIG. 6 illustrates the environment of the claimed design and forms no part thereof.