PlainPatent

CPC technology class · F28

F28G - Cleaning OF Internal OR External Surfaces OF Heat-exchang…

Cleaning of internal or external surfaces of heat-exchange or heat-transfer conduits, e.g. water tubes or boilers. 438 US utility patents granted 2015–2025, with the leading assignees and year-by-year filing trajectory.

438
US patents granted
F28
Parent CPC class
20
Active assignees
+17%
5-yr velocity

The verdict

Cleaning OF Internal OR External Surfaces OF Heat-exchang… ranks #551 of 670 CPC technology areas - 438 US patents granted since 2015, with filing up 17% over five years.

#551
of 670 CPC technology areas
438
US patents granted, 2015–2025
Stoneage
leading assignee (35)
+17%
filing velocity, last 5 yrs
Top assignee: Stoneage, Inc. (35 patents)

CPC subclass F28G - CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS - covers 438 US utility patents granted between 2015 and 2025 according to USPTO PatentsView records, within the broader CPC class F28 (HEAT EXCHANGE IN GENERAL). See our CPC classification guide for how the system works.

The competitive landscape in F28G is shaped by 20 distinct companies actively filing in this space. Stoneage, Inc. leads with 35 patents, followed by Terydon, Inc. at 16 grants and Crossford International, Llc at 14.

Filing activity in F28G is up 17% over the past five years versus 2015-2019, a relatively steady filing pace. All counts come directly from USPTO PatentsView and reflect US granted utility patents only.

Is F28G innovation accelerating?

US utility-patent grants per year in F28G, 2015–2025 - recent five years are up 17% versus 2015–2019.

2030405060 20152016201720182019202020212022202320242025 32

Who leads F28G?

The 12 most active assignees in CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS - wider bars mean more grants

patents

What this shows Stoneage is the most active filer in F28G, holding 35 of the 438 patents in this class. Concentration at the top signals how contestable this technology area is for new entrants.

Source USPTO PatentsView, granted utility patents As of 2015–2025 grant years
View data table
Top patent holders in CPC subclass F28G
Rank Company Patents in F28G
#1 Stoneage, Inc. 35
#2 Terydon, Inc. 16
#3 Crossford International, Llc 14
#4 Westinghouse Electric Company Llc 10
#5 Fractal Heatsink Technologies Llc 8
#6 Peinemann Equipment B.v. 5
#7 DOS Viejos Amigos, Llc 5
#8 HS Marston Aerospace Limited 4
#9 Thomas Engineering Solutions & Consulting, Llc 4
#10 Horton, Inc. 3
#11 Framo Engineering AS 3
#12 Quest Integrity Group, Llc 3
#13 Heatcraft Refrigeration Products Llc 2
#14 I.d.e. Technologies Ltd 2
#15 Martin Gmbh Für Umwelt- Und Energietechik 2
#16 Tubemaster, Inc. 2
#17 Dominion Engineering, Inc. 2
#18 HRST, Inc. 2
#19 Boyle Energy Services & Technology, Inc. 2
#20 Hyfra Industriekuhlanlagen Gmbh 2

About This Class

CPC subclass F28G belongs to class F28.

438 patents were granted in this class between 2015 and 2025.

20 companies actively patent in this space.

Classification System

Cooperative Patent Classification (CPC) is a hierarchical patent classification system used by the USPTO and EPO.

← All Technology Classes Technology Rankings →

Footprint here vs. claim strategy

Each dot is a leading F28G assignee, placed by how many patents it holds in this class (horizontal) against its company-wide average claims per patent (vertical) - a read on whether the class is led by broad-but-shallow filers or focused deep-claim players.

Top 14 F28G assignees by class footprint. Bubble size = patents in F28G. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Top 14 F28G assignees by class footprint. Bubble size = patents in F28G. Source: USPTO PatentsView (claim depth is company-wide across all classes). Scatter plot of 14 data points (bubble-sized by third dimension). 510152025 010203040 Patents in F28G Avg claims / patent (company-wide) StoneageTerydonCrossford Internation…Westinghouse ElectricFractal HeatsinkPeinemann Equipment B…Dos Viejos AmigosHs Marston AerospaceThomas Engineering So…HortonFramo Engineering AsQuest Integrity GroupHeatcraft Refrigerati…I D E
Top 14 F28G assignees by class footprint. Bubble size = patents in F28G. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Frequently Asked Questions

What is CPC class F28G?
CPC subclass F28G covers CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS. It belongs to CPC class F28 (HEAT EXCHANGE IN GENERAL), with 438 US utility patents granted since 2015.
How many patents have been filed in F28G?
438 US utility patents were granted in CPC subclass F28G between 2015 and 2025, based on USPTO PatentsView data.
Which company holds the most patents in F28G?
Stoneage, Inc. leads F28G with 35 patents, making it the most active assignee in this technology area.
How is patent data for F28G collected?
Patent data comes from USPTO PatentsView, a public research dataset maintained by the United States Patent and Trademark Office. It covers all US granted utility patents and assigns CPC codes based on the technology described in each patent.
What is the difference between CPC class and subclass?
A CPC class (e.g., F28) is a broad technology category. Subclasses like F28G provide finer granularity within that category. PlainPatent organizes data at the subclass level (4-character codes) for the most useful view of technology domains.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from USPTO PatentsView - official U.S. government patent data. See our methodology for computation details. Retrieved and formatted by PlainPatent Editorial

Every figure on PlainPatent is rendered directly from USPTO source data, no number is typed in by an editor. This page draws directly on USPTO source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.