THREADED JOINT FOR STEEL PIPE

WIPO Patent Application WO/2014/045973

A1

In the present invention, a threaded joint for a steel pipe is provided with: a pin having an male thread formed of a two-stage thread, and a sealing surface comprising a tapered surface and curved surface formed at an intermediate part of the two-stage thread; and a box having a female thread formed of a two-stage thread, and a sealing surface comprising a tapered surface and curved surface formed at an intermediate part of the two-stage thread. The taper angle of the tapered surface of the pin and the taper angle of the tapered surface of the box are substantially the same. The threaded joint has a structure in which, in the course of fastening the male thread and the female thread together, the pin and the box interfere with one another in the radial direction while the sealing surface of the pin and the sealing surface of the box are in contact, thereby causing at least some of each of the sealing surfaces to be in close contact across the entire periphery; and is provided with a contact-pressure-increasing mechanism for increasing the contact pressure between the sealing surface of the pin and the sealing surface of the box once fastening has concluded.

OKU YOUSUKE (JP)
YAMAMOTO TATSUYA (JP)
SUGINO MASAAKI (JP)
ELDER RUSSELL (US)

PCT/JP2013/074562

March 27, 2014

September 11, 2013

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NIPPON STEEL & SUMITOMO METAL CORP (JP)
VALLOUREC OIL & GAS FRANCE (FR)

F16L15/04

WO2002059519A1

2002-08-01

JPH10148281A	1998-06-02
JP2007205361A	2007-08-16
JPS4899716A	1973-12-17
JP2000130654A	2000-05-12
US20040108719A1	2004-06-10
US4153283A	1979-05-08
US3856337A	1974-12-24
US4736967A	1988-04-12

See also references of EP 2899440A4

SHIGA Masatake et al. (JP)
Masatake Shiga (JP)

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