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 grant trajectory.

438
US patents granted
#4/5
in F28
2.0%
F28 class share
+1%
5-yr velocity

The verdict

According to USPTO PatentsView, Cleaning Of Internal Or External Surfaces Of Heat-exchang… ranks #551 of 670 CPC technology areas - 438 US patents granted since 2015, with recorded grant volume up 1% over five years.

#551
of 670 CPC technology areas
438
US patents granted, 2015–2025
Stoneage
leading assignee (35)
+1%
grant velocity, last 5 yrs

How F28G's grant cadence moved

Between 2020–2024, F28G recorded 196 grants versus 195 in 2015–2019 (+1% equal-window velocity). Across complete years, output peaked in 2019 at 52 grants and bottomed in 2015 at 28 (+86% peak-over-trough). Lead assignee Stoneage, Inc. holds 8.0% of the class ; the top three share 14.8%.

Leaderboard read

F28G concentration, lead at 8.0%

Stoneage, Inc. leads this historical grant record at 8.0% of F28G - us corporation assignees hold 79% of class grants (128 of 163). Figures describe granted US utility patents in this CPC subclass, not current investment or legal strength.

Leader's share
8.0%

35 of 438 grants

Top three share
14.8%

of the class's recorded grants

Lead over #2
19

more grants than Terydon, Inc.

Where F28G sits inside F28

Among 5 subclasses in F28 (Heat Exchange IN General), F28G ranks #4 and holds 2.0% of the parent class's 21,601 recorded grants. Sibling chips below are the other subclasses in the same parent class, not the nationwide volume/lead-share peers further down.

F28F 10,136 F28D 10,118 F28C 493 F28B 416

Rising assignees active in F28G

Company-wide grant multiples (2022–2024 vs 2019–2021) among assignees with ≥5 patents in this subclass. Growth is company-wide; class patent counts are subclass-specific.

  1. #1 Crossford International, LLC 4.50x 2 → 9 company-wide · 14 in F28G
  2. #2 DOS Viejos Amigos, LLC 3.00x 1 → 3 company-wide · 5 in F28G
  3. #3 Peinemann Equipment B.V. 2.00x 2 → 4 company-wide · 5 in F28G
  4. #4 Fractal Heatsink Technologies LLC 1.60x 5 → 8 company-wide · 8 in F28G
  5. #5 Westinghouse Electric Company LLC 0.99x 103 → 102 company-wide · 10 in F28G

F28G grants by year, peak 2019 (52)

US utility-patent grants per year in F28G, 2015–2025 - recent five years are up 1% 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

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). Scatter plot of 14 data points (bubble-sized by third dimension). 510152025 010203040 Patents in F28G Avg claims / patent (company-wide) StoneageTerydonCrossford Internationa…Westinghouse ElectricFractal HeatsinkPeinemann Equipment B…Dos Viejos AmigosHs Marston AerospaceThomas Engineering…HortonFramo Engineering AsQuest Integrity GroupHeatcraft Refrigeratio…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).

Questions about F28G

Which company holds the most patents in F28G?
Stoneage, Inc. leads F28G with 35 patents (8.0% of the subclass). By PatentsView assignee type, us corporations account for 79% of class grants.
Which F28G assignees grew fastest recently?
Among assignees with ≥5 grants in F28G, Crossford International, LLC shows the highest company-wide grant multiple (4.50x: 2 grants in 2019–2021 → 9 in 2022–2024) while holding 14 patents in this subclass. Growth is company-wide, not class-only.
How does F28G compare inside parent class F28?
Inside F28 (Heat Exchange IN General), F28G ranks #4 of 5 subclasses by grant volume and holds 2.0% of the parent class total. The largest sibling is F28F (10,136 grants).

What to do with this data

F28G in context - here's where to go next.

Figures reflect USPTO PatentsView grant data through 2026-05-15; pending applications not yet granted are not counted.

Methodology - F28G figures are USPTO PatentsView granted-utility totals for this subclass (438 grants in the tracked window).

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.