The ornamental design for a pipelineweight, as shown and described.
FIG. 1 is a perspective view of a pipeline weight showing my new design;
FIG. 2 is an elevational front view thereof, the front and back of the pipeline weight are mirror images;
FIG. 3 is an elevational side view thereof, the right side and left side of the pipeline weight are mirror images;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof; and,
FIG. 6 is a perspective view thereof, the broken lines of the pipeline and additional pipeline weights along the pipeline are included for the purpose of illustrating environmental structure that forms no part of the claimed design.