| F | SK | MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING |
| F22 | KL | STEAM GENERATION (chemical or physical apparatus for generating gases B01J; chemical generation of gas, e.g. under pressure, Section C; removal of combustion products or residues, e.g. cleaning of the combustion contaminated surfaces of tubes of boilers, F23J; generating combustion products of high pressure or high velocity F23R; water heaters not for steam generation F24H , F28; cleaning of internal or external surfaces of heat-transfer conduits, e.g. water tubes of boilers, F28G) |
| F22B | UKL | METHODS OF STEAM GENERATION; STEAM BOILERS (steam engine plants where engine aspects predominate F01K; domestic central-heating systems using steam F24D; heat exchange or heat transfer in general F28; generation of vapour in the cores of nuclear reactors G21) |
| F22D | UKL | PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER; FEED-WATER SUPPLY; CONTROLLING WATER LEVEL; CIRCULATING WATER WITHIN BOILERS (chemical treatment of water, e.g. purification, C02F; enclosed heat-exchange apparatus in general F28D; controlling in general G05) |
| F22G | UKL | SUPERHEATING OF STEAM (steam-separating arrangements in boilers F22B 37/26) |