(19)

(11)

EP 0 160 023 A1

(12)

(43) Date of publication: 06.11.1985 Bulletin 1985/45 (21) Application number: 84903776.0 (22) Date of filing: 21.09.1984

(51) International Patent Classification (IPC):  E21B 33/ 12( . ) E21C 37/ 00( . ) E21B 33/ 127( . ) E21C 37/ 10( . ) (86) International application number: PCT/US1984/001529 (87) International publication number: WO 1985/001545 (11.04.1985 Gazette 1985/09)

(84) Designated Contracting States: AT BE CH DE FR GB LI LU NL SE (30) Priority: 05.10.1983 US 19830539088 (71) Applicant: CENTURY, Bernard Amos Cleveland, OH 44106 (US)	(72) Inventor: CENTURY, Bernard Amos Cleveland, OH 44106 (US) (74) Representative: van der Beek, George Frans, et al  Nederlandsch Octrooibureau Scheveningseweg 82 P.O. Box 29720 NL-2502 LS 's-Gravenhage NL-2502 LS 's-Gravenhage (NL)