We claim the ornamental design for an elbow fitting, as shown and described.
FIG. 1 is an isometric view of an embodiment of our design for an elbow fitting;
FIG. 2 is a front view of the design of the elbow fitting shown in FIG. 1;
FIG. 3 is a rear view of the design of the elbow fitting shown in FIG. 1;
FIG. 4 is a bottom view of the design of the elbow fitting shown in FIG. 1;
FIG. 5 is a top view of the design of the elbow fitting shown in FIG. 1;
FIG. 6 is a left side view of the design of the elbow fitting shown in FIG. 1; and,
FIG. 7 is a right side view of the design of the elbow fitting shown in FIG. 1.
The broken lines depict portions of the elbow fitting that form no part of the claimed design. The dot-dash lines depict the boundaries between claimed and unclaimed subject matter and form no part of the claimed design.