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:
Sep. 05, 1995
Filed:
Jun. 28, 1993
Glen Gibbs, Warren, MI (US);
Arnold T Johnson, Davisburg, MI (US);
ITT Corporation, New York, NY (US);
Abstract
A seamless double-walled metal tube which has an outer wall composed of steel having a face-centered cubic grain structure, an inner wall concentrically disposed within the outer wall, the inner wall composed of a steel having a face-centered cubic grain structure, the inner wall having an outerwardly oriented surface directed toward an inwardly oriented surface of the outer wall. The seamless double-wall metal tube also has an intermediate bonding metal region interposed between and metallurgically bonded to the inner wall and the outer wall. The intermediate bonding region is composed of a metal capable of metallurgically bonding with the inner wall and the outer wall. The seamless double-walled metal tube can be produced by instantaneously elevating the temperature of the surface of the steel employed in an unsealed double-walled metal tube to a brazing temperature while maintaining the tube material in a humidified gaseous atmosphere; maintaining the surface temperature of the steel tube for an interval sufficient to permit fusion between the metal capable of metallurgically bonding with the steel in the inner and the outer wall; after metal fusion has been achieved, allowing the resulting fused metal material to cool to a first lowered temperature at a rate which retards the formation of fine-grained steel crystals in the metal; and after reaching a metallurgical transformation point, rapidly cooling the fused tube to a temperature below which the metal capable of metallurgical bonding is not reactive with oxygen.