Self-locking threaded connection partially in non-locking engagement

Patent metadata

Field	Value
Publication number	US-12372171-B2
Application number	US-202118250306-A
Country	US
Kind code	B2
Filing date	Oct 20, 2021
Priority date	Oct 28, 2020
Publication date	Jul 29, 2025
Grant date	Jul 29, 2025

Abstract

A flush self-locking threaded connection partially in a non-locking engagement comprises a first and a second tubular component provided respectively with male and female threaded zone at their respective ends. First portions of the male and female threaded zones with varying thread width and root cooperate along a self-locking tightening arrangement. A locking region within the threaded connection is located in the middle of non-locking regions, and radially centered to the pipe body API tolerances in order to withstand high torque and seal performances.

First claim

The invention claimed is:

1. A threaded connection comprising:
a first tubular component including a first pipe body and a male member, the male member being arranged at a distal end of the first pipe body, an external peripheral surface of the male member comprising at least one male threaded zone, said at least one male threaded zone being arranged along a longitudinal axis of the threaded connection between the first pipe body and a male terminal surface; and
a second tubular component comprising a second pipe body and a female member, the female member being arranged at a distal end of the second pipe body, an internal peripheral surface of the female member comprising at least one female threaded zone, said at least one female threaded zone being arranged along the longitudinal axis of the threaded connection between the second pipe body and a female terminal surface,
wherein the male threaded zone having a first male threaded portion and a second male threaded portion, the first male threaded portion being arranged along the longitudinal axis of the threaded connection between the second male threaded portion and the first pipe body, a width of the thread roots (WR p1 ) of the first male threaded portion decreasing in a direction oriented from the male terminal surface towards the first pipe body, a width of the thread roots (WR p2 ) of the second male threaded portion being constant, said width of the thread roots (WR p2 ) of the second male threaded portion presenting a minimum root width of the male threaded zone, a male thread closest to the male terminal surface presenting a maximum root width value of the male threaded zone,
wherein the female threaded zone comprising a first female threaded portion and a second female threaded portion, the first female threaded portion being arranged along the longitudinal axis of the threaded connection between the second female threaded portion and the second pipe body, a width of the thread roots (WR b1 ) of the first female threaded portion decreasing along a direction oriented from the female terminal surface towards the second pipe body, a width of the thread roots (WR b2 ) of the second female threaded portion being constant, said width of the thread roots (WR b2 ) of the second female threaded portion presenting a minimum root width of the female threaded zone, a female thread closest to the female terminal surface presenting a maximum root width value of the female threaded zone,
wherein the first male treaded portion and the first female threaded portion are partially made up in a self-locking arrangement in order to provide a locking region in the threaded connection and wherein the threaded connection is a flush connection, and
wherein the locking region is located between a first non-locking region and a second non-locking region.

2. The threaded connection according to claim 1 , wherein the first male threaded portion comprises at least 90% of perfect threads and wherein the first female threaded portion comprises at least 90% of perfects threads.

3. The threaded connection according to claim 1 , wherein the locking region of the made-up connection represents represent more than 55% of the total make up length of engaged male and female threads.

4. The threaded connection according to claim 1 , wherein the male threaded zone comprises a single continuous spiral such that a lead of the male stab flanks (SFL_p) changes at a single male stab flanks changing location on the male threaded zone, and the female threaded zone comprises a single continuous spiral such that a lead of the female stab flanks (SFL_b) changes at a single female stab flank changing location on the female threaded zone, the male stab flank changing location and the female stab flank changing location being at different locations along the longitudinal axis of the threaded connection such that the locking region is defined between the male stab flank changing location and the female stab flank changing locations, and wherein a lead of the male load flanks (LFL_p) remains constant along the male threaded zone and a lead of the female load flanks (LFL_b) remains constant along the female threaded zone.

5. The threaded connection according to claim 1 , wherein the male threaded zone comprises a single continuous spiral such that a lead of the male load flanks (LFL_p) changes at a single male load flank changing location on the male threaded zone, and the female threaded zone comprises a single continuous spiral such that a lead of the female load flanks (LFL_b) changes at a single female load flank changing location on the female threaded zone, the male load flank changing location and female load flank changing location being at different locations along the longitudinal axis of the threaded connection such that the locking region is defined between the male load flank changing location and the female load flank changing location, and wherein a lead of the male stab flanks (SFL_p) remains constant along the male threaded zone and a lead of the female stab flanks (SFL_b) remains constant along the female threaded zone.

6. The threaded connection according to claim 1 , wherein a wedge ratio in the locking region is below 0.2 mm.

7. The threaded connection according to claim 1 , wherein the male and female threaded zones have a taper generatrix forming a taper angle with the longitudinal axis of the threaded connection, and wherein a taper corresponding to tan (taper angle) is in the range of ⅙ to 1/18, and wherein crests and roots of the male and female threads of the threaded zones are parallel to the taper generatrix in the locking region.

8. The threaded connection according to claim 1 , wherein a middle locking location is identified at axial half length of the locking region such that a pitch line diameter TDavg at the middle locking location M is as follows
( OD min+ ID min)÷2< TD avg<( OD max+ ID max)÷2

in which ODmin is a minimal pipe body outer diameter,
Idmin is the minimal male element inner diameter,
ODmax is a maximum pipe body outer diameter, and
Idmax is the maximum male element inner diameter.

9. The threaded connection according to claim 1 , wherein a middle locking location is identified at axial half length of the locking region such that a length Lnl from that middle locking location to a longitudinal side of the locking region is such that
Lnl ≥( TD avg−BCCSD−2×THpitch)÷taper

in which THpitch is a radial distance from pitch line to root or crest in the locking region,
BCCSD is the box critical cross section diameter,
taper is the taper of the threaded zone.

10. The threaded connection according to claim 1 , wherein maximum root width value (WRpmax) of the male threaded zone is set below twice the minimum root width (WRpmin) value of the male threaded zone and/or maximum female root width value (WRbmax) of the female threaded zone is set below twice the minimum root width value (WRbmin) of the female threaded zone
WRb max≤2* WRb min

and/or
WRp max≤2* Wrp min.

11. The threaded connection according to claim 1 , wherein the root of a female thread which is closest to the second pipe body has the same root width as the root of a male thread which is closest to the first pipe body.

12. The threaded connection according to claim 1 , wherein respective threads of the second male threaded portion and/or the second female threaded portion have imperfect thread height and or vanishing thread teeth.

13. The threaded connection according to claim 1 , wherein the female threaded zone starts as of the female terminal surface and the male threaded zone starts as of the male terminal surface.

Assignees

• Vallourec Oil & Gas France
• Nippon Steel Corp

Inventors

• Ott Wesley
• Van Gorp Logan
• Granger Scott

Classifications

• F16L15/001

  with conical threads · CPC title

• E21B17/043 Primary

  with locking means · CPC title

• E21B17/0423

  with plural threaded sections, e.g. with two-step threads · CPC title

• F16L15/06 Primary

  characterised by the shape of the screw-thread · CPC title