(19)

(11)

EP 0 638 157 A1

(12)

(43) Date of publication: 15.02.1995 Bulletin 1995/07 (21) Application number: 92915874.0 (22) Date of filing: 02.04.1992

(51) International Patent Classification (IPC):  F16L 37/ 098( . ) (86) International application number: PCT/US1992/002703 (87) International publication number: WO 1993/020379 (14.10.1993 Gazette 1993/25)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU MC NL SE (71) Applicant: PROPRIETARY TECHNOLOGY, INC. Southfield, MI 48037 (US)	(72) Inventor: BARTHOLOMEW, Donald Dekle Mt. Clemens, MI 48045 (US) (74) Representative: Neumann, Ernst Dieter, Dipl.-Ing., et al  Harwardt Neumann Patent- und Rechtsanwälte, Brandstrasse 10 D-53721 Siegburg D-53721 Siegburg (DE)