The ornamental design for a linkpin for conveyorchain, as shown and described.
FIG. 1 is a front elevational view of a link pin for conveyor chain in accordance with our new design, the rear elevational view being an identical view thereof;
FIG. 2 is a top plan view thereof, the bottom plan view being an identical view thereof;
FIG. 3 is a side elevational view thereof, the other side being an identical view thereof; and,