Invention Grant
- Patent Title: Circumferential welded joint of line pipe, method of forming circumferential welded joint of line pipe, and line pipe
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Application No.: US14647993Application Date: 2013-11-19
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Publication No.: US09833856B2Publication Date: 2017-12-05
- Inventor: Takahiro Sakimoto , Satoshi Igi , Tomoyuki Yokota
- Applicant: JFE STEEL CORPORATION
- Applicant Address: JP Tokyo
- Assignee: JFE STEEL CORPORATION
- Current Assignee: JFE STEEL CORPORATION
- Current Assignee Address: JP Tokyo
- Agency: Young & Thompson
- Priority: JP2012-260455 20121129
- International Application: PCT/JP2013/081092 WO 20131119
- International Announcement: WO2014/084084 WO 20140605
- Main IPC: B23K9/028
- IPC: B23K9/028 ; B23K31/02 ; B23K9/23 ; B23K9/00 ; B23K9/18 ; B23K101/10 ; B23K103/04

Abstract:
A circumferential welded joint of a line pipe is formed by butting against each other end portions of steel pipes having a yield strength according to 5L Specification of API Standards not smaller than 555 N/mm2 and welding the butted portions in a circumferential direction. A joint strength ratio σmatch=(TS-w/TS-b)·(YS-w/YS-b) represented by a product of a ratio between a tensile strength TS-w of a weld metal and a tensile strength TS-b of a base material and a ratio between a yield strength YS-w of the weld metal and a yield strength YS-b of the base material, and a critical equivalent plastic strain εp-cri [%] for ductile crack generation in a base material heat affected zone satisfy Equation (1), and the yield strengths YS-w, YS-b of the weld metal and base material satisfy Equation (2). σmatch>4.85εp-cri−0.31 (1) YS-w/YS-b≧1.0 (2)
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