the installation for hardening tubular workpieces 1 features numerous adjacent chambers 2 which are open at the top and can be closed with cover plates 3 in order to be able to subject the workpieces 1 located in the chambers 2 to a vaporising process to achieve more effective hardening . in accordance with this design embodiment , each of the cover plates 3 of the individual chambers 2 are subdivided into three cover plate segments 4 , each of which can be individually removed from the chambers 2 . due to the resultant reduction in the weight and the reduced dimensions of the cover plate segments 4 , this subdivision of the cover plates 3 results in the facilitation of the handling of the cover plates 3 when the chambers 2 are opened and closed . laterally adjacent to the chambers 2 positioned next to one another provision is made for tracks 5 for an overhead travelling crane 6 , along the bridge 7 of which a crab 8 with a lifting and a lowering hoist 9 for the workpieces 1 can be slid . this hoist 9 consists of a supporting frame 10 which travels above the workpieces 1 to be hoisted and on which the brackets 11 for encompassing the exterior of the workpieces are arranged , as can be seen in fig3 . at the lower ends of the brackets 11 provision is made for dogs 12 which can be positioned perpendicular to the vertical axis of the tubular workpiece 1 and in accordance with fig4 grip under a flange 13 of the metallic bottom ring 14 on which the workpiece 1 is positioned and by means of which it can be elevated , encompassing the tubular workpiece 1 . the dogs 12 can be adjusted into a position at right angles to the axis of the workpiece 1 by moving the brackets 11 laterally , by actuating the dogs 12 at right angles to the brackets 11 , or by rotating the brackets 11 upon their axis as provided for in this embodiment of the arrangement . in order that not only the workpieces 1 , but also the cover plate segments 4 can be lifted by the overhead travelling crane 6 , the overhead travelling crane 6 must be provided with the necessary holding devices for the cover plate segments 4 . although special holding devices for this purpose are conceivable , a particularly simple construction constellation results when the hoist 9 for the workpieces 1 can be utilised . for this purpose and in accordance with fig5 the cover plate segments 4 have pick - up recesses 15 for the dogs 12 on the brackets 11 , with the recesses designed to accommodate the bracket arrangement . therefore , if the hoist 9 in the embodiment provided for is lowered in relation to a cover plate segment 4 , the dogs 12 on the lower ends of the brackets 11 enter the area in which the recesses 15 are located , so that the pick - up recesses 15 are gripped from beneath by the dogs 12 after the brackets 11 have been rotated as shown in fig5 . in this manner , the cover plate segments 4 coupled to the hoist 9 for the workpieces 1 can be lifted from the chamber 2 involved by means of the overhead travelling crane 6 as shown in fig2 . the cover plate segment 4 which has been lifted off can be placed in a stackable storage facility 16 which in accordance with fig1 is located directly adjacent to the rows of chambers 2 in the direction of travel of the overhead travelling crane 6 . the stackable storage facility 16 is located advantageously between the discharge station 17 of the feeder conveyor 18 for the workpieces 1 requiring hardening and the charging station 19 of the discharge conveyor 20 for the hardened workpieces 1 . this spatial arrangement of the feeder conveyor 18 and the discharge conveyor 20 in relation to the stackable storage facility 16 for the cover plate segments 4 means that any empty runs which may have been necessary for the overhead travelling crane 6 between picking up the cover plate segments 4 and the workpieces 1 are avoided in an advantageous manner . however , it is not at all necessary to always convey the cover plate segments 4 removed from the chambers 2 to the stackable storage facility 16 in order to remove them from the stackable storage facility 16 to close the chambers 2 . the loading circumstances can be made much more advantageous if , for instance in accordance with fig1 the chamber section to be closed , ‘ a ’, is not closed using a cover plate segment 4 from the stackable storage facility 16 , but by using the cover plate segment 4 a from the neighbouring chamber 2 , which is to be charged with new workpieces 1 . therefore , the cover plate segment 4 a only needs to be moved the distance of one chamber 2 in order to close the previously open chamber 2 in area ‘ a ’ on the one hand and to open a section of a chamber 2 to be recharged on the other . then the already treated and fully hardened workpieces 1 can be removed from the open chamber using the overhead travelling crane 6 and replaced with workpieces to be treated which are conveyed by the feeder conveyor 18 , while the hardened workpieces 1 are removed from the installation by the discharge conveyor 20 . this charging and discharging procedure of the chambers 2 is repeated chamber after chamber until the final chamber in the sequence of chambers has been opened and the cover plate segment 4 required to close this chamber must be taken from the stackable storage facility 16 . the cover plate segments 4 stored in the stackable storage facility 16 are those from the first chamber 2 opened in the charging sequence .