Skip to content
PCE
Search Classifications
Search for IPC and CPC classification codes or keywords
CPC Main Group
E21D 5/00

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

8 direct subcodes

Child Classifications

Navigate with arrow keys, Enter to open

  • 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