IPC Main Group
E21D 11/00 Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings , e.g. by assembling
Introduced: September 1968
Last revised: January 2006
Classification Context
- Section:
- FIXED CONSTRUCTIONS
- Class:
- EARTH OR ROCK DRILLING; MINING
- Subclass:
- SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
Related Keywords
INSULATION of tunnelsINSULATION of tunnelsLINING(S) of mine galleries; LINING(S) of mine shaftsLINING(S) tunnelsroof supports for MINE(S)
5 direct subcodes
Child Classifications
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- E21D 11/02 Lining predominantly with wood
- E21D 11/04 Lining with building materials
- E21D 11/14 Lining predominantly with metal
- E21D 11/38 Waterproofing; Heat insulating; Soundproofing; Electric insulating
- E21D 11/4 Devices or apparatus specially adapted for handling or placing units of linings for tunnels or galleries
Top Applicants
Top 10 applicants by patent filingsfor class E21, 2013–2023, worldwide · Source: EPO PATSTAT
- HALLIBURTON ENERGY SERVICES GROUP US 26,607
- PETROCHINA COMPANY 14,382
- SINOPEC (CHINA PETROCHEMICAL CORPORATION) 10,137
- CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 6,517
- BAKER HUGHES US 6,269
- SCHLUMBERGER TECHNOLOGY US 5,929
- SAUDI ARABIAN OIL COMPANY SA 5,880
- SOUTHWEST PETROLEUM UNIVERSITY 4,477
- CHINA UNIVERSITY OF MINING AND TECHNOLOGY 4,357
- SCHLUMBERGER TECHNOLOGY NL 4,219