The ornamental design for the “pipe insulator,” as shown and described.
FIG. 1 is a top perspective view of a pipe insulator showing my new design.
FIG. 2 is a bottom perspective view thereof.
FIG. 3 is a front view thereof.
FIG. 4 is an end view thereof.
FIG. 5 is a top view thereof; and,
FIG. 6 is a bottom view thereof.
The pipe insulator is shown broken away with solid, cut-off lines in the figures to indicate that no specific length is being claimed—it is understood that the interrupted portion of the pipe insulator has a uniform shape and appearance throughout its length.