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:
Mar. 26, 2002
Filed:
May. 21, 1999
Kayo Hasegawa, Tokyo, JP;
Keiji Sugawara, Tokyo, JP;
Masatsugu Nishi, Tokyo, JP;
Hideyuki Wada, Tokyo, JP;
NKK Corporation, Tokyo, JP;
Abstract
This invention provides an oil well pipe which is resistant to fracturing caused by ground subsidence by providing a sliding layer on the outside of the oil well pipe to reduce the frictional force acting on the oil well pipe. Furthermore, by constituting the sliding layer by a material and a thickness so that the residual negative frictional force becomes 2×10 N/m or less after 1 year of deformation at the operating temperature of the oil well pipe, or by the sliding layer comprising a material of which the stiffness factor S(t) after 1 year of deformation is in the range from 10 N/m to 10 N/m at the operating temperature of the oil well pipe and providing an adhesive layer between the pipe body and the sliding layer, thereby reducing the sliding phenomenon upon construction which restricts the properties of the sliding layer. Further, by the improvement of the adhesive force of the