The dataset in scope contains 55 published records spanning 2015 through the 2026 data cut-off, all matched against search terms covering liquid hydrogen transfer, cryogenic transfer lines, boil-off recovery, flow-rate control, electrostatic grounding, vapour return lines and automated coupling connections. These 55 records also form the complete assignee ranking, so every figure quoted for concentration or leadership is a share of that same total. Because publication lags filing by roughly 18 months, the true count for 2025 and 2026 filings will rise as more applications publish.

The ranking covers 28 companies, with the leader holding 13 of the 55 records in scope and the top five combined holding 32 records, or 58.2% of the total. That leaves a long tail: the tenth-ranked entrant holds only 2 records, so beyond the leading handful the field is held by companies with a handful of filings each. This is a ranked list drawn directly from the data endpoint, not a curated top-50 or top-100, so smaller or newer filers can and do appear in it.

Storage and pressure-vessel engineering, classified under F17C, still accounts for just over half of the 55 records in scope and includes the most-cited single document in the dataset. Newer records, including the representative fault-detection patent filed in mid-2025, lean toward control and monitoring methods such as cumulative-sum anomaly detection rather than tank or coupling hardware. That pattern — older filings concentrated in storage hardware, newer filings drifting toward software-based monitoring — is visible in the data but should be read cautiously given the 18-month publication lag on the most recent years.

Control-of-variable methods (G05D), pumps (F04B), valves (F16K) and electric-propulsion-adjacent claims (B60L) each account for 7.3% or less of the 55 records, well below the storage and marine-transfer blocs. Electrostatic grounding and automated coupling connection, both explicitly covered by the search scope, do not surface as a distinct heavily-claimed class, suggesting the safety-interlock and grounding layer around a refuelling event carries less claim density than the storage vessel it protects. That gap is a reasonable place to look for a first claim that does not collide with the existing storage-hardware art.

Filings peaked at 13 in 2021 and fell to 5 by 2024, a -62% change across that three-year span according to the dataset. That drop should not automatically be read as declining interest, because patent publication typically lags the underlying filing date by around 18 months, so the 2025 and 2026 figures in this dataset are still incomplete. A fuller picture of the 2022-2024 filing wave, and any recovery since, will only be visible once those later years finish publishing.