The ornamental design for corrugated drain conduit, as shown and described.
FIG. 1 is a front elevation view of a corrugated drain conduit showing my new design;
FIG. 2. is a right side elevation view, the opposite side being a mirror image thereof;
FIG. 3 is a top elevation view thereof; and,
FIG. 4 is a front perspective view thereof.
The views of the corrugated drain conduit not shown form no part of the claimed design. The dashed lines represent environmental elements only and form no part of the claimed design. The break lines in FIGS. 1–4 indicate that no specific length is being claimed.