(19)

(11)

EP 0 172 226 A1

(12)

(43) Date of publication: 26.02.1986 Bulletin 1986/09 (21) Application number: 85901173.0 (22) Date of filing: 30.01.1985

(51) International Patent Classification (IPC):  F16L 59/ 15( . ) (86) International application number: PCT/US1985/000161 (87) International publication number: WO 1985/003478 (15.08.1985 Gazette 1985/18)

(84) Designated Contracting States: AT CH DE GB LI NL SE (30) Priority: 02.02.1984 CH 19840000493 (71) Applicant: THE DOW CHEMICAL COMPANY Midland Michigan 48640-1967 (US)	(72) Inventor: LARSON, Anders, G. CH-8810 Horgen (CH) (74) Representative: Blum, Rudolf Emil Ernst  c/o E. Blum & Co Patentanwälte Vorderberg 11 CH-8044 Zürich CH-8044 Zürich (CH)