US 12,276,359 B2
Threaded connection for pipe
Satoshi Maruta, Tokyo (JP); Yousuke Oku, Tokyo (JP); Pierre Martin, Meudon (FR); and Daly Daly, Meudon (FR)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP); and VALLOUREC OIL AND GAS FRANCE, Aulnoye-Aymeries (FR)
Appl. No. 17/756,518
Filed by NIPPON STEEL CORPORATION, Tokyo (JP); and VALLOUREC OIL AND GAS FRANCE, Aulnoye-Aymeries (FR)
PCT Filed Dec. 22, 2020, PCT No. PCT/JP2020/047837
§ 371(c)(1), (2) Date May 26, 2022,
PCT Pub. No. WO2021/145163, PCT Pub. Date Jul. 22, 2021.
Claims priority of application No. 2020-005809 (JP), filed on Jan. 17, 2020.
Prior Publication US 2022/0412486 A1, Dec. 29, 2022
Int. Cl. F16L 15/00 (2006.01)
CPC F16L 15/007 (2013.01) 8 Claims
OG exemplary drawing
 
1. A threaded connection for pipe including a tubular pin and a tubular box, the pin and the box adapted to be made up as the pin is screwed into the box, wherein:
the pin includes: a first male thread; a second male thread located further toward a tip than the first male thread and having a smaller diameter than the first male thread; a pin intermediate shoulder surface located between the first male thread and the second male thread; a pin end shoulder surface located at the tip of the pin; and a pin sealing surface located between the second male thread and the pin end shoulder surface;
the box includes: a first female thread adapted to be engaged by the first male thread when the connection is made up; a second female thread adapted to be engaged by the second male thread when the connection is made up; a box intermediate shoulder surface adapted to be in contact with the pin intermediate shoulder surface when the connection is made up; a box end shoulder surface corresponding to the pin end shoulder surface; and a box sealing surface located between the second female thread and the box end shoulder surface and adapted to be in contact with the pin sealing surface along an entire circumference when the connection is made up;
an axial distance between the box intermediate shoulder surface and the box end shoulder surface of the box before make-up, LB, is larger than an axial distance between the pin intermediate shoulder surface and the pin end shoulder surface of the pin before make-up, LP;
a difference between the axial distances, (LB−LP), is such that, when the connection is made up and upon application of an axial compressive load, the pin end shoulder surface starts to be in contact with the box end shoulder surface before the threaded connection for pipe yields;
wherein the axial distances LB and LP are such that, when the connection is made up and no axial compressive load is applied, a clearance is formed between the pin end shoulder surface and the box end shoulder surface; and
wherein each of the intermediate shoulder surfaces of the pin and box is constituted by a single flat surface perpendicular to the pipe axis.