This dataset contains 280 published records filed between 2015 and the 2026 cut-off that match cathodic protection monitoring language in either the title/abstract or the claims alongside corrosion or material-degradation terms. That figure counts patent families in the assignee ranking, which is the fairer unit than raw document counts because it neutralises continuations and multi-jurisdiction refiling of the same invention. It is not a count of every corrosion patent — only the subset whose claims tie cathodic protection to monitoring, detection or sensing.

The ranking covers 100 assignees, with the leader holding 12 of the 280 records and the fifth-place filer holding 7. Ownership is concentrated at the very top but thins quickly: the top 5 combined hold 16.1% of all records and the top 10 combined hold 26.4%, meaning most of the ranked list holds only a handful of filings each. That pattern points to a field with a few consistent filers and a long tail of single- or few-filing entrants rather than a two- or three-company duopoly.

Filings peaked at 19 in 2018, the highest single year in the 2015-2026 window, then cooled before rebuilding — the 2021-to-2024 span shows a 25% increase, from 4 to 5 filings. Because publication typically lags filing by around 18 months, the 2025 and 2026 counts in this dataset are undercounts still filling in and should not be read as a decline. Treat 2024 as the most recent year that can be compared like-for-like against earlier full years.

Corrosion and metal-removal claims under IPC class C23F appear in 66.1% of the 280 records, and material analysis and testing under G01N appear in 50.0%, with many records carrying both classes together. Smaller but real activity sits in electric and magnetic measurement (8.6%), pipe fittings (5.4%), structural testing (5.0%), water heaters (3.2%), batteries (2.5%) and foundations (2.1%). Since a single record can carry several classes, these shares add up to more than 100% of the record total, and they mark corrosion-science framing as the dominant claim style over pure electronics.

US4351703A, assigned to Petrolite Corporation in 1982, claims a sacrificial-specimen method: a small metallic specimen exposed to the same cathodic current as the protected structure, with current induced between specimen and structure until their potential difference reaches zero, and the induced current used to infer current density on the structure. Any new filing that measures protection state by inducing current flow into a proportionally sized reference specimen and reading the resulting current density risks overlapping this claim. Designs that instead measure structure potential directly, use non-specimen sensing (fibre-optic, acoustic, electromagnetic), or infer degradation from data analytics rather than an induced-current specimen sit further from this prior art.