THREADED JOINT FOR STEEL PIPE

WIPO Patent Application WO/2017/130234

A1

According to the present invention, a pin (10) is provided with a shoulder surface (11), a first seal surface (12), a first male threaded part (13), a second seal surface (14), and a second male threaded part (15), in this order from the tip end side of the pin (10). A box (20) is provided with a shoulder surface (21), a first seal surface (22), a first female threaded part (23), a second seal surface (24), and a second female threaded part (25). The first male threaded part (13) and the first female threaded part (23) have respective load flank surfaces (13d, 23d) each having a flank angle of less than 0°. The first male threaded part (13) is divided into an incompletely threaded section region (31b) and a completely threaded section region (31a), in this order from the side closer to the second seal surface (14). The incompletely threaded section region (31b) has a length of at least three times longer than the thread pitch, and has a thread height lower than the thread height of the completely threaded section region (31a). In the incompletely threaded section region (31b), gaps are formed between thread peak surfaces (13a, 23a) and thread root surfaces (23b, 13b).

JP2009235874	JOINT FOR EXCAVATION TOOL
JP4930647	Threaded pipe fittings

INOSE KEITA (JP)
SUGINO MASAAKI (JP)
OTA FUMIO (JP)

PCT/JP2016/000341

August 03, 2017

January 25, 2016

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

F16L15/04

JP2007205361A	2007-08-16
JP2002295747A	2002-10-09
JP2013536339A	2013-09-19
JPS62196486A	1987-08-29
JP2015534614A	2015-12-03
US4373754A	1983-02-15
JPH07504483A	1995-05-18

See also references of EP 3409991A4

ASCEND IP LAW FIRM (JP)

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