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:
Dec. 20, 1983
Filed:
Jan. 09, 1981
Kyohei Murata, Kitakyushu, JP;
Heiji Morise, Fukuma, JP;
Yoichi Yazaki, Kitakyushu, JP;
Kazushi Maruyama, Kitakyushu, JP;
Haruyuki Nagayoshi, Kitakyushu, JP;
Etuji Kajiki, Kitakyushu, JP;
Nippon Steel Corporation, Tokyo, JP;
Abstract
Quenched steel pipe is first held at a tempering temperature for a given period of time, then cooled relatively rapidly. While carrying the pipe in the direction of its length, cooling water is sprayed from outside onto its external surface at an average water flux of not lower than 0.05 m.sup.3 /min.m.sup.2 and not higher than 2 m.sup.3 /min.m.sup.2. This cooling is started when the pipe temperature is between 400.degree. C. and 700.degree. C. and ended between room temperature and 350.degree. C. Also, the cooling is effected at a mean cooling rate of not lower than 5.degree. C./sec. and not higher than 40.degree. C./sec. This cooling method improves the collapse strength of a pipe by providing an appropriate tensile residual stress to the internal surface of the pipe and reduces the cooling floor area without sacrificing the collapse strength of the pipe.