The ornamental design for a drainpipestructure, as shown and described.
FIG. 1 is a perspective view of a drainpipe structure showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a cross-sectional view taken from lines 8-8 in FIG. 6.
The ornamental design which is claimed is shown in solid lines in the drawings. The drainpipe structure comprises a base and a stem and they together form a trophy shape for the said design.