The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 20, 2000
Filed:
May. 25, 1999
Ming C Kuo, Cerritos, CA (US);
Other;
Abstract
An outer pipe casing (20) and a concrete tube (26) cast inside, form a pre-stressed concrete pipe in its elementary form. Prior to casting, a layer of non-cohesive material (28) is sprayed on the inside of the pipe casing and an annular ring (32) is welded inside adjacent to each end. A resilient seal ring (46) is captivated into the inwardly facing legs (38) of the second channel (36) of each annular ring and a temporary seal (52) separates each annular ring from the material (28). After the concrete of the tube cures, a pressurized solidifying compound (54) is inserted under pressure to a pathway (42) formed into each annular ring and it is also extruded into a region (30) coated by the non-cohesive material. Pressurization of the compound is sufficient to cause the pipe casing to bulge outwardly and compression of the concrete in the tube is achieved. When the compound hardens, the compressive force remains and pre-loads the pipe. As the outer casing bulges externally when pressurized by the compound, the seal ring (46) is compressed tightly against the concrete of the tube assuring and maintaining an absolute closure between the tube and the annular ring.