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CPC Main Group
E21D 5/00

Lining shafts; Linings therefor (E21D11/00 takes precedence )

Filing statistics

CPC E21D 5/00 belongs to the parent subclass E21D, which recorded 43,973 patent applications worldwide between 2013 and 2023. Annual filings grew from 1,000 in 2013 to 6,074 in 2023 (+507%), peaking at 6,255 applications in 2020. The most active applicants in class E21 are HALLIBURTON ENERGY SERVICES GROUP (27,652 applications), SAUDI ARABIAN OIL COMPANY (7,755 applications) and PETROCHINA COMPANY (7,025 applications).

Source: EPO PATSTAT, worldwide filings

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 (E21D5/01, E21D5/012, E21D5/016 take precedence)
  • E21D 5/04 with brick, concrete, stone, or similar building materials (E21D5/01, E21D5/012, E21D5/016 take precedence)
  • E21D 5/11 with combinations of different materials, e.g. wood, metal, concrete (E21D5/01, E21D5/012, E21D5/016 take precedence)
  • 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 27,652
  2. SAUDI ARABIAN OIL COMPANY SA 7,755
  3. PETROCHINA COMPANY 7,025
  4. BAKER HUGHES US 6,589
  5. SCHLUMBERGER TECHNOLOGY US 6,151
  6. SINOPEC (CHINA PETROCHEMICAL CORPORATION) 4,443
  7. SCHLUMBERGER TECHNOLOGY NL 4,255
  8. CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 3,991
  9. SERVICES PETROLIERS SCHLUMBERGER FR 3,300
  10. SCHLUMBERGER CANADA CA 3,086