Bolted Connections Patents: Who Leads, Where the Gaps Are 2026
Bolted Connections and Slip-Critical Joints: Patent Landscape 2026
78.8% of all 113 records in scope sit with just five assignees, making this one of the more concentrated corners of steel-structure patenting. Filing rose to a peak of 7 records in 2017 and has not returned to that level since. With fewer than four complete years remaining once publication lag is factored in, a growth rate cannot be reliably computed from this window — treat the most recent years as undercounted rather than as a genuine decline.
- 1NIPPON STEEL CORPORATION50
- 2KOBE STEEL LTD18
- 3NIPPON STEEL & SUMITOMO METAL CORP8
- 4TOYO KOHAN CO LTD7
- 5SHINSHU TLO CO LTD6
See the full bolted connections and slip critical joints analysis in Eureka
- The complete ranking, not just the top five
- Every IPC branch with its share of the corpus
- The most-cited records, and where claim space is still thin
Common questions on this landscape
Who are the leading patent holders in slip-critical joint and high-strength bolt technology?
Filing in this space is concentrated: the top five assignees account for 78.8% of all 113 records in scope, and the single leading assignee holds 50 records on its own. The ranking includes 28 companies in total, but by the tenth-ranked firm the count has already fallen to 3 records. Most of the leading holders are Japanese steelmakers, which lines up with Japan being the largest receiving office in this dataset, followed by the United States and Europe.
What is a slip-critical joint and why does hydrogen embrittlement matter to it?
A slip-critical joint relies on friction between clamped steel surfaces, generated by high bolt pretension, to transfer load without the bolt shank ever bearing directly. Hydrogen embrittlement is a delayed-fracture risk in the high-strength bolt steel itself, where absorbed hydrogen can cause sudden failure under sustained clamping load. That is why a large share of the patent activity here — including the most-cited records in this dataset — targets bolt steel microstructure specifically to resist embrittlement rather than only optimising joint geometry.
Is the patent activity in this field growing or slowing down?
Filing peaked in 2017 at 7 records and has not returned to that level in the years since, based on the trend data in scope. However, publication typically lags filing by around 18 months, so the most recent one to two years understate real filing activity and should not be read as a genuine slowdown. Recent-year momentum figures showing zero filings from leading assignees are best treated as an incomplete record rather than a stop in R&D.
Disclaimer. This analysis is based on Patsnap Eureka data drawn from a limited snapshot of global patent records and is provided for general information and reference only. Patent data carries inherent limitations — recent filings are under-counted because of publication lag, counts may be on a record or family basis, classification and applicant-name data may contain errors or duplicates, and the underlying search query defines the scope shown — so the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing here is an exhaustive prior-art, novelty, freedom-to-operate or validity search, nor does it constitute legal, financial or professional advice, and it should not be relied upon as such. Verify independently and review with qualified patent and legal professionals before acting on it.
Method: Filing trend and technology composition. Derived from a Patsnap search on Bolted Connections and Slip Critical Joints covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish. Every share divides by all records in scope. Data: Patsnap Eureka. See the full landscape report.