In 1942, the newly formed Design Bureau of Plant No. 100 proposed a new version of the flamethrower tank, which was based on the serial KV-1. The project manager designated as “Object 232” was engineer S. Fedorenko. In addition to using the tank as a “chemical” (flamethrower), it was assumed that the flamethrower tank would carry out contamination of the area with poisonous substances, the installation of smoke screens and the degassing of the area. Later this car received the designation KV-12M.
In contrast to the KV-8, the engineers of Plant No. 100 retained the main armament of the heavy tank, leaving a 76.2-mm cannon and two 7.62-mm machine guns. The flamethrower was located in the front hull sheet, dismantling the course gun. The housing was also welded with mounting brackets for fastening tanks and partitions for air tubes (the latter were located on the fences and shelves). The “dry” mass of the flamethrower equipment was 2,000 kg, excluding refueling, the total volume of which, depending on the chemicals, ranged from 400 to 1,200 kg. The release of fire mixture was carried out by compressed air from two standard cylinders of 27 liters each. The equipment was protected by a front armored partition 30 mm thick, and the back, side and top armor did not exceed 12 mm.
The construction of the first prototype KV-12 was carried out in April-May 1942. Since all serial tanks went to the front, the plant was provided with an “unaccounted” KV-1 of the early series (serial number 6728), which was used for various kinds of experimental work. The car had a lot of defects in the hull and the turret, but there was no other choice for the Fedorenko brigade. In May 1942, the completely ready KV-12 was transferred to factory tests. In terms of tactical and technical data, this machine was somewhat superior to the KV-8, but in order not to bring down the pace of serial production, the KV-12 was abandoned. 
KV-12 (Object 232) - Experimental chemical tank. Was equipped with 4 external toxin tanks on rear of chassis. Tanks surrounded with 30 mm armour. Not taken into service.
