(19)

(11)

EP 0 551 340 A1

(12)

(43) Date of publication: 21.07.1993 Bulletin 1993/29 (21) Application number: 91917302.0 (22) Date of filing: 02.10.1991

(51) International Patent Classification (IPC):  E21B 17/ 046( . ) E21B 17/ 042( . ) F16L 37/ 252( . ) (86) International application number: PCT/GB1991/001695 (87) International publication number: WO 1992/006322 (16.04.1992 Gazette 1992/09)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB IT LI NL (30) Priority: 02.10.1990 GB 19900021385 (71) Applicant: ASBURY, Anthony John Norfolk, Norwich NR6 7PN (GB)	(72) Inventor: ASBURY, Anthony John Norfolk, Norwich NR6 7PN (GB) (74) Representative: Gillam, Francis Cyril, et al  SANDERSON & CO. European Patent Attorneys 34, East Stockwell Street Colchester Essex CO1 1ST Colchester Essex CO1 1ST (GB)