US 12,110,992 B2Granted

Threaded joint of pipe and method for connecting same

AssigneeJfe Steel Corporation

InventorsMasaki Yoshikawa, Seigo Goto, Seiji Ozaki, Hideo Sato

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Abstract

A threaded joint wherein a relationship between shoulder angle parameters and thread taper angle parameters for a coupling and a pair of pins inserted from both ends of the coupling is defined by the following expression (1), and a tightening torque with which the threaded joint is tightened is 60% or more and 85% or less of a yield torque determined by the following expression (2): - 1.5 ⁢ ° ≤ Δ ⁢ θ - Δ ⁢ ω ≤ 2. ° , ( 1 ) T = ( T S + T D ) ⁢ 1 12 ( 2 ) T S = f t ⁢ P c ⁢ E 7 2 ⁢ ( 2 ⁢ π ⁢ E 7 ) ⁢ L 4 ⁢ 1 2 P c = E ⁢ ρ m 2 ⁢ ( ( W 2 ) 2 - ( E 7 2 ) 2 ) ⁢ ( ( E 7 2 ) 2 - ( d 2 ) 2 ) 2 ⁢ ( E 7 2 ) 3 ⁢ ( ( W 2 ) 2 - ( d 2 ) 2 ) T D = Y m ⁢ A S ( P 2 ⁢ π + R t ⁢ f s cos ⁢ Θ + R s ⁢ f s ) .

A threaded joint comprising:

a pair of pins each having a male thread, as a male tapered thread, provided on an outer circumferential surface at a distal end of a first steel pipe;
and
a coupling having female threads, as female tapered threads, provided on an inner circumferential surface at both ends of a second steel pipe, the female threads being configured to be screwed into the male threads, wherein
the threaded joint is configured such that shoulder faces at the distal ends of the pair of pins are brought into contact with each other when the male threads are screwed into the female threads at both ends of the coupling,
a relationship between shoulder angle parameters and thread taper angle parameters for the coupling and the pair of pins inserted from both ends of the coupling is defined by the following expression (1), and
a tightening torque with which the threaded joint is tightened is 60% or more and 85% or less of a yield torque determined by the following expression (2):
−1.5°≤Δθ−Δω≤2.0° (1),
where
Δθ is a shoulder angle parameter that is a sum of shoulder angles OA and OB before tightening of the pair of pins, i.e., Δθ=θA+θB, and
Δω is a thread taper angle parameter that is a sum of thread taper angle differences ΔωA and Δω before tightening of the coupling and the pair of pins, i.e., Δω=Δω+Δω,
T
=
(
T
S
+
T
D
)
⁢
1
12
(
2
)
T
S
=
f
t
⁢
P
c
⁢
E
7
2
⁢
(
2
⁢
π
⁢
E
7
)
⁢
L
4
⁢
1
2
P
c
=
E
⁢
ρ
m
2
⁢
(
(
W
2
)
2
-
(
E
7
2
)
2
)
⁢
(
(
E
7
2
)
2
-
(
d
2
)
2
)
2
⁢
(
E
7
2
)
3
⁢
(
(
W
2
)
2
-
(
d
2
)
2
)
T
D
=
Y
m
⁢
A
S
(
P
2
⁢
π
+
R
t
⁢
f
s
cos
⁢
Θ
+
R
s
⁢
f
s
)
,
where
T:
yield torque [ft-lbf]
TS is shouldering torque [inch-lbf],
TD is delta torque [inch-lbf],
Pc is thread contact pressure [psi],
ft is thread frictional coefficient (=0.035),
fs is thread frictional coefficient (=0.080),
E7 is thread pitch diameter [inch],
L4 is thread length [inch],
w is coupling outer diameter [inch],
d is pipe inner diameter [inch],
Dbv is bevel diameter [inch],
P is thread lead (=1/TPI) [inch],
ρm is thread interference on diameter [inch],
As is shoulder cross-sectional area (=π(Dbv2−d2)/4) [inch2],
Rt is average mean thread radius (=E7/2) [inch],
Rs is average shoulder radius (=(Dbv+d)/4),
Θ is thread flank angle [deg.],
E is Young's modulus [psi], and
Ym is material yield stress [psi].

160 more elements

Facts

Application

18/044,990Filed 30 Sep 2020

Published

US 2023/0383875 A130 Nov 2023

Granted

8 Oct 2024

Term ends

Not estimatedThe source records don’t support an estimate.

Classification7 codes

F16L 15/004
With conical threads: with axial sealings having at least one plastically deformable sealing surface
F16L 15/04
Screw-threaded joints; Forms of screw-threads for such joints: with additional sealings
F16L 15/06
Screw-threaded joints; Forms of screw-threads for such joints: characterised by the shape of the screw-thread
F16L 15/08
Screw-threaded joints; Forms of screw-threads for such joints: with supplementary elements

Abstract

Claims5