Pipe joint

Details Pipe joint Pipe joint

1999-08-03

2004-03-16

Swann, J. J. (Department: 3677)

Pipe joints or couplings

Particular interface

Tapered

C285S333000, C285S355000, C285S390000, C285S092000

Reexamination Certificate

active

06705648

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a pipe joint capable of enhancing a working property when a tapered male screw section of a pin is perpendicularly inserted into a tapered female screw section of a box or coupling and successively turned so that the male screw section can be screwed into the female screw section.
DESCRIPTION OF THE PRIOR ART
Conventionally, as a pipe joint used for an oil well pipe, a pipe pile for construction work and so forth, there is provided a joint composed of a tapered square thread for pipe use including a trapezoidal screw thread and buttress screw thread in which a tapered male screw section
52
of a pin
51
of a pipe
50
is engaged with a tapered female screw section
55
of a box
54
of a short pipe
53
as shown in FIGS.
9
(A) and
9
(B). FIG.
9
(B) is an enlarged view showing a state of starting the engagement of this tapered square screw joint for pipe use.
In order to clearly explain the stabbing property (a performance of the connection can be made up immediately after stabbing) of the tapered square screw joint, a profile of a male thread ridge
56
of the tapered male screw section
52
is made to be the same as that of a female thread ridge
57
of the tapered female screw section
55
, and a top face
58
of the ridge of the male screw and a top face
59
of the ridge of the female screw are made to be parallel to tapered face T
f
. FIG.
9
(B) is a cross-sectional view showing a state of engagement of the ridge of the male screw
56
with the ridge of the female screw
57
which are going to engage with each other. That is, a tapered face, on which top faces
58
of the ridges of the male screw- section
52
are continuously arranged, and a tapered face, on which top faces
59
of the ridges of the female screw section
55
are continuously arranged, precisely coincide with each other. In this drawing, a position of the tapered male screw section
52
in the circumferential direction is set at a position of the tapered female screw section
55
in the circumferential direction so that the ridges
56
of the male screw section can be located at bottoms
60
of the ridges
57
of the female screw section. As can be clearly seen in the drawing, it is impossible to screw the tapered male screw section
52
into the tapered female screw section
55
in the above state.
Referring to FIG.
10
(B) showing a buttress screw joint of API, which is commonly used as an oil well pipe screw, the stabbing property of a square screw joint for pipe use will be explained below. In this case, explanations will be made into a mechanism in which a male thread ridge
63
and a female thread ridge
64
are screwed into bottoms of the threads after the tapered male screw section
61
has been inserted into the tapered female screw section
62
.
Elements of the buttress screw of API are described as follows. Taper T={fraction (1/16)} (or 62.5 mm/m). This taper is a ratio of change in the diameter. Pitch P=5.08 mm. Height of the ridge H=1.575 mm. Stabbing flank angle &eegr;=10°. Load flank angle &ggr;=3°. Straight line sections of the top faces
65
,
66
of the ridges of the male and the female screw are parallel to tapered face T
p
(pitch line). Corner R of the top face
65
of the male screw is 0.76 mm and corner R of the top face
66
of the female screw is 0.2 mm.
FIG.
10
(A) is a view showing a state in which the tapered male screw section
61
is fitted into the tapered female screw section
62
in the most appropriate circumferential direction. Different from the above case into which the tapered square screw joint for pipe use is incorporated, an opening section
68
of a bottom
67
of the tapered female screw section
62
is larger than the top face
65
of the ridge
63
of the male screw, and when R is formed at the corner, the difference can be further increased. When the tapered male screw section
61
is perpendicularly dropped in the above condition, a corner section
69
of the male ridge
63
of the tapered male screw section
61
can be slightly mounted on a corner section
70
of the ridge
64
of the tapered female screw section
62
. When the tapered male screw section
61
is turned in the above state, the tapered males crew section
61
is spirally fitted into the tapered female screw section
62
.
In order to fit the tapered male screw section
61
into the tapered female screw section
62
, relative positions of the male and the female screw line are not necessarily limited to the positions shown in FIG.
10
(A). The tapered male screw section
61
can be fitted into the tapered female screw section
62
even at apposition at which the tapered female screw section
61
is shifted downward from the position shown in FIG.
10
(A) so that corner R of the stabbing flank face
71
of the ridge
63
of the male screw section comes into contact with corner R of the stabbing flank face
72
of the tapered female screw section
62
. When the tapered male screw section
61
is screwed into the tapered female screw section
62
by an angle in the circumferential direction corresponding to this shift, an allowance can be provided in the circumferential direction so that the tapered male screw section
61
can be properly screwed into the tapered female screw section
62
.
In normal inserting and screwing work, the tapered male screw section
61
is inserted into the tapered female screw section
62
, and then the tapered male screw section
61
is turned to the above circumferential position at which the ridge
63
of the tapered male screw section
61
can be properly mounted on the ridge
64
of the tapered female screw section
62
. Since the ridge
63
of the male screw section has not been engaged yet with the ridge
64
of the female screw section at this time, there is a possibility that gall occurs unless the axis of the tapered male screw section
61
agrees with the axis of the tapered female screw section
62
. In the case of a conductor casing, the diameter of which is large, since the rotational angle is large, it is difficult to search for the screwing position. Accordingly, when a range is large, in which the circumferential position at which the ridge
63
of the male screw section is screwed to the ridge
64
of the female screw section, it possible to reduce a rotational angle necessary for turning the male screw section to an appropriate position, that is, the stabbing property of the tapered screw joint is high. When clearance G between width W of the opening section
68
of the bottom
67
of the tapered female screw section
62
and width V of the top face
65
of the ridge of the tapered male section is large, another advantage can be provided as follows. When the tapered male screw section
61
is dropped by an amount corresponding to clearance G so that the tapered male screw section
61
is mounted on the stabbing flank face
72
of the ridge
64
of the tapered female screw section
62
, it is possible to ensure a distance (clearance G in the axial direction of the pipe ×taper T)/2 for mounting the tapered male screw section
61
on the stabbing flank face
72
of the ridge
64
of the tapered female screw section
62
in the radial direction. Therefore, it is possible to screw the tapered male screw section into the tapered female screw section stably.
As can be understood by the above explanations, the stabbing property, which is defined as a performance by which the tapered male screw section can be smoothly screwed into the tapered female screw section after the tapered male screw section has been inserted into the tapered female screw section, is enhanced when a circumferential range (&thgr;) in which screwing can be started at a position as it is when the tapered male screw section
61
is inserted into the tapered female screw section
62
, and also the stabbing property is enhanced when a depth &dgr;, by which the stabbing flank face
71
of the male thread ridge
63
is mounted on the stabbing flank face
72
of the female thread ridge
64
,

Affiliated with

Also associated with

Rating

Pipe joint does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Pipe joint, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pipe joint will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3278743