PlainPatent

CPC technology class · F23

F23M - Casings

Casings, linings, walls or doors specially adapted for combustion chambers, e.g. firebridges; devices for deflecting air, flames or combustion products in combustion chambers; safety arrangements specially adapted for combustion apparatus; details of combustion chambers, not otherwise provided for. 568 US utility patents granted 2015–2025, with the leading assignees and year-by-year filing trajectory.

568
US patents granted
F23
Parent CPC class
20
Active assignees
-23%
5-yr velocity

The verdict

Casings ranks #525 of 670 CPC technology areas - 568 US patents granted since 2015, with filing down 23% over five years.

#525
of 670 CPC technology areas
568
US patents granted, 2015–2025
General Electric
leading assignee (45)
-23%
filing velocity, last 5 yrs
Top assignee: General Electric Company (45 patents)

CPC subclass F23M - CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR - covers 568 US utility patents granted between 2015 and 2025 according to USPTO PatentsView records, within the broader CPC class F23 (COMBUSTION APPARATUS; COMBUSTION PROCESSES). See our CPC classification guide for how the system works.

The competitive landscape in F23M is shaped by 20 distinct companies actively filing in this space. General Electric Company leads with 45 patents, followed by 8 Rivers Capital, Llc at 12 grants and Rinnai Corporation at 6.

Filing activity in F23M is down 23% over the past five years versus 2015-2019, a notable slowdown that may signal a maturing field. All counts come directly from USPTO PatentsView and reflect US granted utility patents only.

Is F23M innovation accelerating?

US utility-patent grants per year in F23M, 2015–2025 - recent five years are down 23% versus 2015–2019.

020406080100 20152016201720182019202020212022202320242025 16

Who leads F23M?

The 12 most active assignees in CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR - wider bars mean more grants

patents

What this shows General Electric is the most active filer in F23M, holding 45 of the 568 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 F23M
Rank Company Patents in F23M
#1 Ansaldo Energia Switzerland Ag 17
#2 8 Rivers Capital, Llc 12
#3 Rinnai Corporation 6
#4 Ansaldo Energia IP UK Limited 6
#5 Brand Shared Services Llc 6
#6 Blasch Precision Ceramics, Inc. 6
#7 Ener-core Power, Inc. 5
#8 Clearsign Combustion Corporation 4
#9 Clearsign Technologies Corporation 4
#10 Palmer Labs, Llc 4
#11 Eberspächer Climate Control Systems Gmbh 3
#12 Total Raffinage Chimie 3
#13 OCV Intellectual Capital, Llc 3
#14 Fosbel, Inc. 3
#15 TPS IP, Llc 3
#16 Rolls-royce High Temperature Composites, Inc. 2
#17 Refractory Intellectual Property Gmbh & Co. KG 2
#18 Eltek S.p.a. 2
#19 PAUL Wurth S.a. 2
#20 Ensyn Renewables, Inc. 2

About This Class

CPC subclass F23M belongs to class F23.

568 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 F23M 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 F23M assignees by class footprint. Bubble size = patents in F23M. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Top 14 F23M assignees by class footprint. Bubble size = patents in F23M. Source: USPTO PatentsView (claim depth is company-wide across all classes). Scatter plot of 14 data points (bubble-sized by third dimension). 010203040 05101520 Patents in F23M Avg claims / patent (company-wide) Ansaldo Energia Switz…8 Rivers CapitalRinnaiAnsaldo Energia Ip UkBrand Shared ServicesBlasch Precision Cera…Ener-core PowerClearsign CombustionClearsignPalmer LabsEberspÄCher Climate C…Total Raffinage ChimieOcv Intellectual Capi…Fosbel
Top 14 F23M assignees by class footprint. Bubble size = patents in F23M. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Frequently Asked Questions

What is CPC class F23M?
CPC subclass F23M covers CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR. It belongs to CPC class F23 (COMBUSTION APPARATUS; COMBUSTION PROCESSES), with 568 US utility patents granted since 2015.
How many patents have been filed in F23M?
568 US utility patents were granted in CPC subclass F23M between 2015 and 2025, based on USPTO PatentsView data.
Which company holds the most patents in F23M?
General Electric Company leads F23M with 45 patents, making it the most active assignee in this technology area.
How is patent data for F23M 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., F23) is a broad technology category. Subclasses like F23M 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.