F28G CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OF BOILERS
Introduced: September 1968
Classification Context
- Section:
- MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- Class:
- HEAT EXCHANGE IN GENERAL
- Subclass:
- CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OF BOILERS
Description
F28G covers apparatus and methods for removing fouling, scale, deposits, and other contaminants from the interior or exterior surfaces of heat-exchange conduits, including boiler tubes, pipes, and similar thermal transfer systems. This classification encompasses mechanical cleaning devices (brushes, scrapers, sponge balls), chemical cleaning processes, and combined approaches designed to maintain heat transfer efficiency and system integrity. It applies to both in-service cleaning operations and maintenance procedures for industrial heat exchangers, steam generators, and related equipment. Adjacent classes F28D (heat exchangers) and F22B (steam generation) address the heat-exchange devices themselves, while F28G focuses specifically on their cleaning and surface maintenance.
Filing statistics
IPC subclass F28G recorded 17,528 patent applications worldwide between 2013 and 2023. Annual filings grew from 596 in 2013 to 3,049 in 2023 (+412%). The most active applicants in class F28 are VALEO SYSTEMES THERMIQUES (1,902 applications), MITSUBISHI ELECTRIC CORPORATION (1,327 applications) and GREE ELECTRIC APPLIANCES (1,152 applications).
Source: EPO PATSTAT, worldwide filings
In class comparison
F28G ranks 4th of 5 subclasses with filings in F28, with 17,528 applications between 2013 and 2023, 5.4% of the class. Annual filings grew 412% from 2013 to 2023, above the class as a whole (+126%).
| Rank | Subclass | Title | Applications | Share |
|---|---|---|---|---|
| 1 | F28D, Heat-Exchange Apparatus, Not Provided for in Another Subclass, in Which the Heat-Exchange Media Do Not Come Into Direct Contact; Heat Storage Plants or Apparatus in General | Heat-Exchange Apparatus, Not Provided for in Another Subclass, in Which the Heat-Exchange Media Do Not Come Into Direct Contact; Heat Storage Plants or Apparatus in General | 137,561 | 42.1% |
| 2 | F28F, Details of Heat-Exchange or Heat-Transfer Apparatus, of General Application | Details of Heat-Exchange or Heat-Transfer Apparatus, of General Application | 136,716 | 41.9% |
| 3 | F28C, Heat-Exchange Apparatus, Not Provided for in Another Subclass, in Which the Heat-Exchange Media Come Into Direct Contact Without Chemical Interaction | Heat-Exchange Apparatus, Not Provided for in Another Subclass, in Which the Heat-Exchange Media Come Into Direct Contact Without Chemical Interaction | 18,596 | 5.7% |
| 4 | F28G | Cleaning of Internal or External Surfaces of Heat-Exchange or Heat-Transfer Conduits, e.g. Water Tubes of Boilers | 17,528 | 5.4% |
| 5 | F28B, Steam or Vapour Condensers | Steam or Vapour Condensers | 16,074 | 4.9% |
Source: EPO PATSTAT, worldwide filings
Related Keywords
8 direct subcodes
Child Classifications
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- F28G 1/00 Non-rotary, e.g. reciprocated, appliances
- F28G 11/00 Cleaning by combustion processes, e.g. using squibs, using travelling burners
- F28G 13/00 Appliances or processes not covered by groups; Combinations of appliances or processes covered by groups
- F28G 15/00 Details
- F28G 3/00 Rotary appliances
- F28G 5/00 Cleaning by distortion
- F28G 7/00 Cleaning by vibration
- F28G 9/00 Cleaning by flushing or washing, e.g. with chemical solvents
Top Applicants
Top 10 applicants by patent filingsfor class F28, 2013–2023, worldwide · Source: EPO PATSTAT
- VALEO SYSTEMES THERMIQUES FR 1,902
- MITSUBISHI ELECTRIC CORPORATION JP 1,327
- GREE ELECTRIC APPLIANCES 1,152
- MAHLE INTERNATIONAL DE 999
- ALFA LAVAL SE 960
- HANON SYSTEMS KR 917
- DENSO CORPORATION 905
- DENSO CORPORATION JP 802
- CHINESE ACADEMY OF SCIENCES 787
- XIAN THERMAL POWER RESEARCH INSTITUTE COMPANY 762