Abstract: A molded plastic vessel is made by hot plate welding together of weld bosses provided respectively on mating rim portions of first and second vessel forming component parts. The first molded part has a weld boss and a shroud which is located radially inboard of the weld boss and projects toward the second part. The second part has a weld boss axially aligned with the weld boss of the first part for mating thereto, and a shroud projecting toward the first part and spaced radially inboard of the shroud of the first part. Upon hot plate melting of weld bosses and the subsequent pressing together of the first and second parts, the shroud of the first part engages and pushes the melt flash projecting inboard of the weld boss of the first part into the space between the weld boss and shroud of the second part to thereby divert the melt flash from overflowing into the interior of the vessel.