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IPC Main Group
E21D 5/00

Lining shafts; Linings therefor

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

LINING(S) of mine galleries; LINING(S) of mine shaftsTUBBING for mine shafts

8 direct subcodes

Child Classifications

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  • E21D 5/01 using prefabricated lining lowered into a hole filled with liquid or viscous mass
  • E21D 5/012 Use of fluid-tight or anti-friction material on outside of, or between, lining layers
  • E21D 5/016 Bearer curbs
  • E21D 5/02 with wood
  • E21D 5/04 with brick, concrete, stone, or similar building materials
  • E21D 5/11 with combinations of different materials, e.g. wood, metal, concrete
  • E21D 5/12 Accessories for making shaft linings, e.g. suspended cradles, shutterings

Top Applicants

Top 10 applicants by patent filingsfor class E21, 2013–2023, worldwide · Source: EPO PATSTAT

  1. HALLIBURTON ENERGY SERVICES GROUP US 26,607
  2. PETROCHINA COMPANY 14,382
  3. SINOPEC (CHINA PETROCHEMICAL CORPORATION) 10,137
  4. CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 6,517
  5. BAKER HUGHES US 6,269
  6. SCHLUMBERGER TECHNOLOGY US 5,929
  7. SAUDI ARABIAN OIL COMPANY SA 5,880
  8. SOUTHWEST PETROLEUM UNIVERSITY 4,477
  9. CHINA UNIVERSITY OF MINING AND TECHNOLOGY 4,357
  10. SCHLUMBERGER TECHNOLOGY NL 4,219