Submerged Entry Nozzle Patents: Who Leads, Where the Gaps Are 2026
- 61.0% concentration. The top 5 of 52 ranked assignees hold 141 of 231 records in scope — a field where a handful of refractory and steel majors have occupied most of the claim space.
- Filing peaked in 2017. 26 records that year against a 2021→2024 span that fell 50%, though 2025-onward counts are still filling in as publications lag filing by roughly 18 months.
- Casting dominates, refractories trail. B22D metal casting covers 90.5% of the 231 records, while ceramics and refractory materials (C04B) sit at just 2.6% — a narrow slice given how central refractory wear is to this problem.
Filing growth compares 2021 (2 records) with 2024 (1) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 231 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Submerged entry nozzles, slide gate nozzles and tundish stopper rods sit at the point in continuous casting where molten steel flow control decides slab quality, clogging risk and refractory life. This landscape draws on 231 published records filed between 2015 and 2026 that combine nozzle or stopper-rod hardware with the operating problems that drive most disputes and design-arounds: clogging, argon injection, flow asymmetry, refractory erosion, port angle design and level control stability. Patent families, not raw document counts, are the unit used for the assignee ranking, which neutralises multi-jurisdiction filing by the largest players.
The scope is deliberately narrow: it pairs a specific piece of hardware with the specific failure modes engineers actually file against, rather than casting equipment in general. That makes the concentration and white-space findings below more load-bearing than they would be in a broader ceramics-or-casting search.
Filing trend and technology composition
Two views of the same 231 records: how filing activity moved year over year, and which IPC subclasses the claims actually sit in.
Filing trend, 2017-2026
Filings peaked at 26 in 2017. The 2021-to-2024 span, the most recent window that can be read as complete, fell 50% (2 to 1) — 2025 and 2026 counts are still incomplete because publication trails filing by roughly 18 months, so that recent drop should not be read as the field cooling.
IPC subclass composition
B22D (metal casting) covers 90.5% of the 231 records, making it the default classification for nearly every filing in scope. Secondary classes — B21B metal rolling at 7.8%, C21C steelmaking at 6.1%, C22C alloys at 3.9% — trail well behind, and C04B refractory ceramics sits at just 2.6% despite refractory erosion being one of the search terms that defined this dataset.
Shares are the percentage of the 231 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Submerged Entry Nozzle and Flow Control with Eureka
This page is one run against one query. Ask Eureka your own question about submerged entry nozzle and flow control and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative and most-cited filings
US6016941A — Submerged Entry Nozzle
A submerged entry nozzle for introducing molten steel into a casting mold is disclosed. The nozzle includes nozzle structure defining a central bore and two transverse exit ports communicating with the bottom of the central bore, the central bore terminating at an upwardly dish-shaped bottom surface that extends to the periphery of the nozzle structure and forms the lower surface regions of the exit ports, whereby molten steel flowing across the upwardly dish-shaped bottom surface is directed outwardly and upwardly from the nozzle structure.Filed by International Steel Group Inc., published 2000-01-25. Its dish-shaped bottom surface and dual transverse exit-port geometry remain a frequently cited reference point for flow-directing nozzle designs.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4791978A | Gas permeable stopper rod | 62 |
| 2 | US6016941A | Submerged entry nozzle | 38 |
| 3 | US5681499A | Method and compositions for making refractory shapes having dense, carbon free surfaces and shapes made there… | 36 |
| 4 | US5884685A | Quality prediction and quality control of continuous-cast steel | 35 |
| 5 | WO1996001710A1 | Method of casting and rolling steel using twin-roll caster | 33 |
| 6 | US4870037A | Prevention of Al2O3 formation in pouring nozzles and the like | 25 |
| 7 | GB2444805A | Nozzle | 22 |
| 8 | US6074600A | Modification of tundish dam to minimize turbulence | 22 |
| 9 | JP1990006040A | Gas-permeable stopper rod | 21 |
| 10 | WO1996001708A1 | Twin-roll caster and rolling mill for use therewith | 20 |
Citation counts are drawn from within this searched corpus and favour older filings; treat them as a measure of influence on later art, not of current commercial importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Four readings of the same dataset, aimed at where to file, who to watch and where the claim space still has room.
The top of the field is crowded
141 of the 231 records in scope belong to just five of the 52 ranked assignees. Filing a broad nozzle-geometry or flow-control claim without a freedom-to-operate check against this group is a weak starting position.
Past the leaders, the tail thins fast
The top 10 add only another 19.5 percentage points over the top 5, then the remaining 42 ranked assignees split the rest. That gap between fifth place (12 records) and tenth (8 records) is where single-application entrants sit.
Casting hardware dominates the classification
B22D covers nearly every record in scope, while refractory materials (C04B, 2.6%) and furnace accessories (F27D, 2.2%) are thinly claimed relative to how often erosion and clogging show up in the search terms themselves.
Influence sits with older filings
The most-cited record, US4791978A on gas-permeable stopper rods, dates from well before this dataset's filing window. High citation counts here mark foundational prior art, not current filing activity.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to submerged entry nozzle and flow control, with the prior art for and against each one.
Who holds the claim space
Fifty-two assignees are ranked in this dataset. Five of them account for 61.0% of all 231 records, and recent-year filing counts across that leading group have dropped to zero, consistent with the broader 2021-2024 decline rather than any one company's retreat.
Integrated steelmakers anchor the top ranks
The leading assignees combine global steel producers with refractory and flow-control specialists, reflecting how nozzle and stopper-rod patents sit at the intersection of steelmaking operations and materials supply.
Joint filings cluster around a small number of partnerships
Co-assignee activity is concentrated in a handful of recurring pairings between steel producers and equipment or automation partners, rather than spread evenly across the ranked list.
Most ranked entrants hold a handful of records each
Once past the top 10 (80.5% of records), the remaining ranked assignees split a small residual share, typical of a field where a few large filers set the baseline art and everyone else files narrowly around it.
| Assignee | Recent year | YoY |
|---|---|---|
| ArcelorMittal | 0 | — |
| ABB (Schweiz) AG | 0 | — |
| Vesuvius Crucible Co. | 0 | — |
| ASEA Brown Boveri (ABB) | 0 | — |
| Pohang Iron & Steel Co., Ltd. (POSCO) | 0 | — |
| Nucor Corp. | 0 | — |
| Hoogovens Staal BV | 0 | — |
| Foseco International Ltd. | 0 | — |
Where to take this analysis
The dataset points to a field with a settled top tier and several narrower branches that have not been heavily claimed. Two directions follow from that.
Check freedom-to-operate against the top 5
Any new nozzle geometry, argon-injection scheme or level-control method should be screened against the leading assignees' portfolios before drafting, given they hold 61.0% of the 231 records in scope.
Run a freedom-to-operate search in EurekaProbe the under-claimed branches
Refractory coatings, furnace-integrated sensing and composite nozzle components show thin filing density relative to how often they appear as failure modes in the wider art — a first-mover claim there faces less crowded prior art.
Explore white space in EurekaCommon questions on this landscape
The dataset ranks 52 assignees, and the top 5 together hold 141 of the 231 records in scope, or 61.0%. That group mixes integrated steel producers with refractory and flow-control equipment specialists, since nozzle and stopper-rod patents typically sit at the boundary between steelmaking operations and materials supply. The gap between fifth place (12 records) and tenth place (8 records) marks where the field thins into a long tail of smaller filers.
Filing peaked in 2017 at 26 records and the most recent complete window, 2021 to 2024, shows a 50% decline from 2 to 1 record. However, 2025 and 2026 figures are not yet reliable indicators because patent publication lags filing by roughly 18 months, so the true recent trend is understated in any dataset cut off this close to the present. Treat the 2021-2024 figure as the most defensible recent signal, not the 2025-2026 numbers.
US6016941A, filed by International Steel Group Inc. and published in 2000, claims a submerged entry nozzle with a central bore terminating in an upwardly dish-shaped bottom surface and two transverse exit ports that direct molten steel outward and upward. Any nozzle design using that specific dish-shaped bottom geometry combined with dual transverse exit ports sits close to this claim and needs a design-around review. It does not block nozzle designs built on different bore-termination geometries or single-port configurations, which is where much of the surrounding art has clustered.
Refractory materials classified under C04B cover only 2.6% of the 231 records and furnace accessories under F27D just 2.2%, both thin relative to how central refractory erosion and furnace-integrated control are to the underlying engineering problem. Composite or polymer nozzle components (B29C overlap) and alloy-tailored stopper rod tips (C22C overlap) show similarly light filing density. These branches are worth a closer freedom-to-operate and white-space check before assuming the space is occupied, since the dominant B22D classification (90.5% of records) has absorbed most filing attention.
The most-cited record in this dataset, US4791978A on gas-permeable stopper rods, carries 62 citations and predates the 2015-2026 filing window used here. Older patents accumulate citations simply by being available longer for later filings to reference, so a high citation count signals influence on subsequent art rather than current commercial relevance. Readers assessing which technology is active today should weight recent filing volume and assignee momentum more heavily than citation counts alone.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.