The article highlights the problems associated with the design of freight rail freight wagons-tanks. A review of existing designs and options for mounting the boiler of the tank wagon to the frame is carried out. The choice of mounting method is part of the development of new generation tank wagons. The development involves the replacement of the boiler material with fiberglass, thereby reducing the tare weight of the wagon and increasing the carrying capacity. One of the issues faced in the manufacture of fiberglass products is the difficulty of fastening and processing of such material. A fastening option is proposed that eliminates the violation of the integrity of the boiler shell due to the lack of fasteners.