(19)

(11)

EP 0 551 318 A1

(12)

(43) Date of publication: 21.07.1993 Bulletin 1993/29 (21) Application number: 91916928.0 (22) Date of filing: 20.09.1991

(51) International Patent Classification (IPC):  E01F 15/ 02( . ) (86) International application number: PCT/GB1991/001613 (87) International publication number: WO 1992/006248 (16.04.1992 Gazette 1992/09)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU NL SE (30) Priority: 02.10.1990 GB 19900021380 (71) Applicant: ALCAN ALUMINIUM UK LIMITED Buckinghamshire S19 0QB (GB)	(72) Inventor: McCRICKERD, Glenn Holmes Workington, Cumbria CA14 4LD (GB) (74) Representative: Lightfoot, Robert Oscar, et al  RAWORTH, MOSS & COOK, Raworth House, 36 Sydenham Road Croydon, Surrey CR0 2EF Croydon, Surrey CR0 2EF (GB)