| 摘要 |
952,460. Joint-making packing; pipe jonts. MARENGO S.p.A. May 17, 1960 [July 20, 1959], No. 17426/60. Headings F2B and F2G. A gasket for a pipe joint, preferably where the pipes are glass-lined, is constituted by a fluorocarbon resin, such as polytetrafluoroethylene or polychlorotrifluoroethylene, enveloping a core of compressible material, the joint-making surfaces of the gasket being treated with a solution of anhydrous ammonia and metallic sodium to increase the frictional resistances of such surfaces in engagement with the parts of the pipes being joined. The gasket is made from a tape 11 which is formed to make it take up the form of a closed ring of U-shaped cross-section, the contacting edges being buttwelded together; welding is effected by disposing the ends of the tape between heated pressure blocks which extend for a substantial distance on either side of the join to minimise the reduction in thickness at the weld. One surface of the ring, namely that which in use is to provide the jointing surfaces, is then roughened by treating it with the above-mentioned solution. After washing, the treated ring is finally assembled about an inner core formed of one or more rings. The rings 17, 18, 19 may be of asbestos with the central ring harder than the outer rings. As described in U.S.A. Specification 2,580,546, the annular core may be formed of corrugated metal with or without asbestos in the corrugations, rubber, ebonite, spirallywound steel ribbon interposed with asbestos strip, or compressed asbestos covered with soft woven asbestos cloth. Specification 765,284 also is referred to. |
