The dataset ranks 43 companies by filing count within this search scope, and the leader holds 22 of the 141 total records. The top 5 assignees together account for 51.1% of all records, and the top 10 reach 75.9%, so the field is concentrated among a small number of established industrial and oilfield equipment suppliers. Beyond that group, most of the remaining ranked companies file only a handful of records each, which is typical of a mature mechanical valve niche rather than an actively expanding one.

Filing peaked at 9 records in 2018 and has generally trended lower since. Comparing 2021 (2 records) to 2024 (1 record), the last two years that can be treated as complete, filing volume fell 50%. Figures for 2025 and 2026 are still incomplete because publication typically lags filing by around 18 months, so those years should not yet be read as confirming further decline.

F16K, the valves and taps classification, covers 46.8% of the 141 records in this dataset and is the clear anchor category. Testing and measurement classes such as G01N and G01L, and control classes such as G05D and F15B, each cover roughly 12-14% of records, indicating that sizing and test-methodology claims are typically filed alongside valve hardware claims rather than as a standalone dominant category. Application-specific classes like E21B (wells) and F24S (solar heat collectors) show that relief valve technology also gets claimed within specific end-use equipment patents.