Seamless Tube Rolling Patents: Top Filers & Filing Trends 2026
- 83.9% concentration. The top five assignees account for 1,485 of the 1,770 records in scope — a field with almost no open middle tier.
- Filing has cooled from its 2019 peak. 108 records filed that year against a 2021→2024 decline of 51 to 21 records, -59% over that span.
- Heat treatment and rolling classes run neck and neck. B21B and C21D each sit at 46.3% of records, meaning most filings pair a rolling step with a metallurgical treatment claim rather than either alone.
Filing growth compares 2021 (51 records) with 2024 (21) — 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 1,770 records in scope (CR5), not by the ranked leaders only.
What this dataset covers
Seamless tube rolling patents span the piercing mill and mandrel mill process chain: billet heating, rotary piercing, wall thickness eccentricity control, sizing mills and finishing. This landscape draws on 1,770 published records filed between 2015 and mid-2026, indexed against terms covering piercing plug life, inner surface defects and tube straightness alongside the core process terms. Records are grouped into 1,770 patent families, so the counts here already net out continuation filings and duplicate jurisdictional copies within a single family.
The corpus concentrates around a small number of integrated steelmakers and mill builders, with receiving offices led by Europe, the United States, Japan and Germany — consistent with a process technology where equipment OEMs and pipe producers both file, and where filings cluster around a handful of long-standing steel groups rather than a broad base of newer entrants.
Filing trends and technology composition
Publication lags filing by roughly 18 months, so the most recent one to two years in any trend chart will always look thinner than the underlying filing activity actually was.
Filings rose to a 2019 peak, then pulled back
Records climbed from 71 in 2017 to a peak of 108 in 2019, then declined; the 2021-to-2024 span moved from 51 to 21 records, a 59% drop. Treat 2025 and 2026 figures as incomplete rather than as evidence of a further slide.
Rolling and heat treatment claims dominate, alloy claims lead
C22C (alloys) appears in 52.3% of the 1,770 records, ahead of B21B (metal rolling) and C21D (heat treatment of metals), each at 46.3%. Because records can carry multiple IPC classes, these shares sum past 100% — they show how often a filing combines a rolling or heat-treatment step with an alloy composition claim, not a partition of the field.
Shares are the percentage of the 1,770 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Seamless Tube Rolling with Eureka
This page is one run against one query. Ask Eureka your own question about seamless tube rolling and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative and most-cited filings
US7506526B2 — Seamless tube piercing/rolling plug, and seamless tube producing method using same
Assigned to Nippon Steel, this filing covers a piercing/rolling plug used with an inclined rotary piercing mill, where front and rear sections of a split plug are held together as an integral tool. At least the front part is made of low alloy steel with oxide films formed on both front and rear surfaces, and the design allows either part to be replaced independently during tube production.Granted 2009-03-24. Still an active reference point for plug-design claims in this corpus given its citation depth and the density of surrounding filings on piercing plug life.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | EP0828007A1 | Process for producing high-strength seamless steel pipe having excellent sulfide stress cracking resistance | 113 |
| 2 | US5071506A | Equipment for making composite tubes including an inflatable heated bladder and a composite mold having a neg… | 92 |
| 3 | US5938865A | Process for producing high-strength seamless steel pipe having excellent sulfide stress cracking resistance | 80 |
| 4 | US20160161028A1 | Seamless steel pipe for line pipe and method for producing the same | 64 |
| 5 | EP1288316A1 | Method for making high-strength high-toughness martensitic stainless steel seamless pipe | 54 |
| 6 | EP1876254A1 | Thick seamless steel pipe for line pipe and method for production thereof | 50 |
| 7 | US5263349A | Extrusion of seamless molybdenum rhenium alloy pipes | 49 |
| 8 | US5379237A | Automated system for controlling the quality of regularly-shaped products during their manufacture | 47 |
| 9 | US6210806B1 | Martensitic stainless steel having oxide scale layers | 46 |
| 10 | US20080047635A1 | Heavy wall seamless steel pipe for line pipe and a manufacturing method thereof | 45 |
Citation counts favour older filings simply because they have had longer to accumulate citations inside this corpus; read them as a signal of influence on later filings, not as a marker of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
Put your own technology through the same analysis
Eureka on the web
When you want the answer in the next five minutes.
The agent works the prompt against patents and technical literature, citing every source.
Run your analysis now →MCP server & REST API
When it has to run inside your own pipeline.
Patent search, landscape analysis and assignee resolution as MCP tools. Drop them into any agent framework, or call REST directly.
Browse MCP servers →What the filing pattern signals
Three threads run through the data: heavy concentration among a small set of filers, a filing peak that has passed, and claim density that clusters tightly around a few IPC subclasses.
The field has almost no open middle tier
Combined, the five leading assignees account for 1,485 of the 1,770 records in scope, and the top ten reach 90.6% at 1,604 records. Fifth place alone holds 55 records and tenth place 14 — a steep drop-off that leaves little room for a mid-sized filer to build a defensible position without engaging incumbents directly.
Activity has pulled back from its 2019 peak
Filings peaked at 108 records in 2019 and have since declined; the comparable 2021-to-2024 window moved from 51 to 21 records. This is a genuine slowdown in a mature process area, not a data artefact — though 2025 and 2026 figures should be read as still filling in.
Rolling claims are rarely filed alone
B21B (metal rolling) and C21D (heat treatment) each cover 46.3% of the 1,770 records, and C22C (alloys) covers 52.3%. The overlap indicates that most substantive filings bundle a mechanical rolling step with a metallurgical composition or heat-treatment claim, raising the bar for anyone trying to file a rolling-only improvement.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to seamless tube rolling, with the prior art for and against each one.
| Assignee | Co-assignee | Shared families |
|---|---|---|
| Nippon Steel Corporation | NIPPON STEEL & SUMITOMO METAL CORP | 47 |
| Sumitomo Metal Industries, Ltd. | NIPPON STEEL & SUMITOMO METAL CORP | 6 |
| Nippon Steel Corporation | Sumitomo Metal Industries, Ltd. | 5 |
| SMS Innse SpA | ZANELLA GUIDO EMILIO | 4 |
| SMS Innse SpA | PALMA VINCENZO | 4 |
| SMS Innse SpA | PACHER MARCELLO | 2 |
| SMS Innse SpA | MARIN PAOLO | 2 |
| SMS Innse SpA | GRASSINO JACOPO | 2 |
Only 10 co-assignee pairs appear in the corpus, and the strongest pairing links two entities within what is now a single consolidated group — a sign that most work here is filed by a single assignee rather than through joint ventures.
Who holds the ground, and where it thins out
The ranking lists 100 companies drawn from the full assignee data behind this corpus, not a curated top 50 or top 100 list. Momentum figures for the leading names show flat or declining recent-year activity, consistent with the corpus-wide slowdown from its 2019 peak.
One filer dominates the corpus
The leading assignee holds 840 of 1,770 records — nearly half the entire dataset on its own — a scale that dwarfs every other filer and defines the freedom-to-operate baseline for the field.
Drop-off is steep past the top ranks
Fifth place holds 55 records; tenth place holds 14. Beyond the leaders, filing activity thins quickly into a long tail of single- or few-filing entrants, many of them regional pipe producers or mill service firms rather than repeat filers.
Joint filings are the exception, not the norm
Only 10 co-assignee pairings appear across the dataset, and the strongest of them links legacy entities that have since merged into a single corporate group — suggesting the apparent joint-filing signal is mostly an artefact of corporate history rather than active collaboration.
| Assignee | Recent year | YoY |
|---|---|---|
| Nippon Steel Corporation | 3 | -57% |
| Sumitomo Metal Industries, Ltd. | 0 | — |
| NIPPON STEEL & SUMITOMO METAL CORP | 0 | — |
| JFE Steel Corporation | 0 | — |
| Kawasaki Steel Corporation | 0 | — |
| SMS Innse SpA | 0 | — |
| Vallourec Tubos do Brasil SA | 0 | — |
| Vallourec Deutschland GmbH | 0 | — |
Where to take this next
The concentration and technology patterns here point to specific follow-up work depending on whether the goal is freedom-to-operate, white-space filing, or tracking a specific incumbent.
Map claims against the leading assignee's portfolio
With one filer holding 840 of 1,770 records, any new filing in core piercing or rolling claims needs a direct comparison against that portfolio's independent claims before drafting.
Run a claim comparison in Eureka →Test the under-claimed branches for freedom to operate
Sub-areas like piercing plug oxide-film formulations and wall thickness eccentricity sensing show thinner filing density than the core process claims and merit a dedicated search before committing R&D spend.
Explore white space in Eureka →Track the post-2019 filing pullback by geography
The 59% decline from 2021 to 2024 may reflect shifting filing strategy rather than reduced R&D; breaking the trend out by receiving office can clarify whether specific jurisdictions are still active.
Build a geography view in Eureka →Common questions on seamless tube rolling patents
One assignee leads the corpus decisively, holding 840 of the 1,770 records in scope — close to half the field on its own. The next four ranked assignees combined bring the top five to 1,485 records, or 83.9% of all records. Beyond the top ten, which together hold 90.6% of records, filing activity thins into a long tail of entities with only a handful of filings each, so freedom-to-operate work should prioritise the leading names first.
Filings peaked in 2019 at 108 records and have declined since. Looking at the most recent complete comparison window, filings dropped from 51 records in 2021 to 21 in 2024, a 59% decline. Because publication typically lags actual filing by around 18 months, 2025 and 2026 figures in any chart are still incomplete and should not be read as confirming a continued drop.
Alloy composition claims under IPC class C22C appear in 52.3% of the 1,770 records, while metal rolling (B21B) and heat treatment of metals (C21D) each appear in 46.3%. Because a single filing can carry multiple IPC classes, these figures overlap substantially, indicating that most substantive filings combine a mechanical rolling step with an alloy or heat-treatment claim rather than filing either in isolation. Smaller classes like metal extrusion and drawing, coating, and steelmaking each sit under 6% of records.
US7506526B2, assigned to Nippon Steel, claims a seamless tube piercing/rolling plug used with an inclined rotary piercing mill, where a split plug's front and rear sections are held as an integral tool, at least the front part uses low alloy steel, and both parts carry oxide films on their surfaces. The design also allows either the front or rear part to be replaced independently. It sits within a dense cluster of piercing-plug filings, making plug-design claims one of the more contested sub-areas in this corpus.
Filing density is visibly lower in specific sub-areas compared with the core piercing and rolling claims — including piercing plug oxide-film formulations, wall thickness eccentricity sensing and control, mandrel mill sizing-stand coordination, inner surface defect inspection integration, and post-rolling tube straightness correction. These branches sit adjacent to heavily claimed process steps but show fewer dedicated filings, making them worth a focused prior-art search before committing to a new filing strategy.
Research Seamless Tube Rolling in depth with Eureka
Go past this page: query the whole seamless tube rolling corpus yourself, in your own scope.
Every answer comes back with patent numbers you can open.
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.