This tray includes spaced apart openings arranged in parallel rows, intended to receive the bodies of the elongated objects, and projections making it possible to place the flanges of the elongated objects inserted in these openings in a determined angular position on the tray when the bodies of these elongated objects are engaged in these openings. According to the invention: said projections are arranged so as to place the length of said flanges in a determined angular position with respect to the rows of openings, and the openings of a first row of openings are arranged with respect to a second row of openings adjacent to said first row, such that after installation of the elongated objects on the tray, the flanges of the objects inserted in the openings of said the first row imbricates with the flanges of the objects inserted in the openings of said second row, i.e. each flange of an object of said the first row is positioned in a space existing between the two adjacent flanges of the objects of said second row, in the immediate vicinity of these two flanges.