Filing in this space is concentrated: the top-ranked assignee holds 57 of the 344 records in scope, and the top 5 assignees combined account for 47.1% of all records. The ranked list covers 100 companies total, drawn from established sealing manufacturers alongside a long tail of single- or few-filing entrants. This concentration means a competitive-intelligence review should focus first on the handful of leaders before scanning the tail for niche claims.

Filing peaked at 19 records in 2019 and has since declined, falling from 17 in 2021 to 4 in 2024 — a -76% move over that three-year span. That said, 2025 and 2026 figures are still incomplete because publication typically lags filing by roughly 18 months, so the most recent years understate true filing activity. The safest reading is that claim space around core constructions has matured rather than that interest in the technology has disappeared.

Core claims in this dataset cover the winding construction itself — alternating metal strip and filler material — plus the filler material composition, surface treatment of the filler tape, and the resulting seating-stress and relaxation behaviour under flange bolt load. A representative filing, US20030193147A1, claims a graphite filler material produced by blast-treating a high-density surface off an expansive graphite tape before winding it into the gasket. Filings also extend into fugitive-emission test methods and flange face finish requirements, reflecting regulatory testing alongside the mechanical design.

Beyond the dominant F16J and F16L classes, smaller but consistent shares of records sit in plasma and particle accelerator equipment (H05H, 6.4% of 344 records), electrolytic production of compounds (C25B, 6.1%) and fusion reactors (G21B, 5.5%). These shares indicate that sealing designs originally built for conventional pipe and flange joints are being adapted for extreme-environment hardware, which is a smaller but growing filing context worth tracking separately from the core gasket claim space.

The top 10 assignees account for 61.3% of all 344 records, leaving roughly 38.7% spread across the remaining ranked companies and a long tail of occasional filers. Co-assignee activity is thin, with only 10 pairs in the dataset, suggesting most filing happens in-house rather than through joint ventures. New entrants are more likely to find open space in the under-claimed adjacent classes — plasma, electrolytic and fusion-related sealing applications — than in the core spiral wound construction itself, where the leading assignees have dense coverage.