Pup joint with integral wing nut retention shoulder

Abstract

A pup joint is provided which comprises a length of pipe, a female sub integral with one end of the pipe and having external threads formed thereon, a male sub integral with the other end of the pipe, a wing nut for threadedly connecting the male sub to the female sub, a set of retainer segments for retaining the wing nut on the pup joint, and a retention shoulder formed on the male sub to maintain the wing nut and retainer segments on the male sub. In a preferred embodiment of the invention, the pipe and the male and female subs are comprised of a single forging, and the retention shoulder is formed by machining the male sub.

Description

This application is a continuation of application Ser. No. 651,646, filed May 22, 1996 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pup joint and, more particularly, to a pup joint which includes means for maintaining the wing nut and retainer segments in a position adjacent the male sub at all times.

2. Description of Related Art

Pup joints are relatively small lengths of pipe used in the oilfield industry to conduct fluids from one piece of equipment to another. Typical pup joints comprise a length of pipe having a male sub located at one end, a female sub located at the other end and a wing nut for connecting the male end of one pup joint to the female end of another pup joint. The male sub includes a spherical sealing surface, and the female sub includes a mating conical scaling surface and a set of external threads. The wing nut is retained on the pup joint by means of a shoulder or a set of retainer segments and engages the threads of the female sub to secure two pup joins together.

Maintaining the wing nut and retainer segments adjacent the male sub end has been somewhat of a challenge in prior art pup joints. In certain prior art pup joints constructed of heavy-wall tubing, the wing nut and retainer segments are held in place by means of an interference fit with the male sub tubing. In lighter weight pup joints, however, this interference fit does not exist. Therefore, when a pup joint is held in a non-horizontal position, the wing nut is permitted to slide down the pup joint, thus creating difficulties during installation.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a pup joint which includes means for maintaining the wing nut and retainer segments adjacent the male sub.

According to the present invention, this and other objects and advantages are achieved by providing a pup joint comprising a length of pipe, a female sub integral with one end of the pipe and having external threads formed thereon, a male sub integral with the other end of the pipe, a wing nut for threadedly connecting the mate sub to the female sub, a set of retainer segments for retaining the wing nut on the pup joint, and a retention shoulder extending radially outwardly from the male sub to maintain the wing nut and retainer segments on the mate sub. In a preferred embodiment of the invention, the pipe and the male and female subs are comprised of a single forging, and the retention shoulder is formed by machining the male sub. The retention shoulder therefore provides a means for preventing the wing nut and retainer segments from sliding down the pup joint.

These and other objects and advantages of the present invention will be made apparent from the following detailed description, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation of one embodiment of a prior art pup joint;

FIG. 2 is a front elevation of another embodiment of a prior art pup joint;

FIG. 3 is a perspective view of a portion of the pup joint of the present invention

FIG. 4 is a partial front elevation of the pup joint of the present invention; and

FIG. 5 is a perspective view of a forging used to construct a pup joint according to one embodiment of the present invention.

FIG. 6 illustrates another embodiment of the present pup joints, in which the version of the male sub 114 shown in FIG. 4 and the version of the female sub 116 shown in FIG. 3 are threaded onto the ends of length of pipe 112. The threaded connection between the subs and the ends of length of pipe 112 are illustrated with dashed lines.

It should be recognized that, while the present invention has been described in relation to the preferred embodiments thereof, those skilled in the art may develop a wide variation of structural details without departing from the principles of the invention. Therefore, the appended claims are to be construed to cover all equivalents falling within the true scope and spirit of the invention.

Claims

1. A pup joint comprising:

a length of pipe having an outside diameter;

a female sub connected to a first end of the length of pipe, the female sub including a conical sealing surface, an outer surface formed adjacent the conical sealing surface and external threads formed on the outer surface;

a male sub connected to distal end of the length of pipe, the male sub including a section having an outside diameter greater than the outside diameter of the length of pipe, the male sub also including a forward shoulder extending radially outwardly therefrom and a spherical sealing surface adjacent the forward shoulder which is adapted to mate with and seal against the conical sealing surface of another such pup joint;

a nut having an internal surface, internal threads formed on the internal surface and a rearward shoulder extending radially inwardly from the internal surface;

one or more retainer segments positioned between the rearward shoulder of the nut and the forward shoulder of the male sub for restricting axial movement of the nut relative to the male sub in a first direction;

a retainer ring positioned in a corresponding groove formed in the retainer segments and having an outer diameter which is greater than the diameter of the rearward shoulder to thereby maintain the nut positioned around the retainer segments; and

a non-removable retention shoulder extending radially outwardly from the male sub positioned rearwardly of the forward shoulder, the retention shoulder comprising an outside diameter greater than the inside diameter of the retainer segments;

whereby the retention shoulder restricts axial movement of the nut and the retainer segments relative to the male sub in a direction opposite the first direction.

2. The pup joint of claim 1, wherein the male sub and the female sub are formed integral with the length of pipe.

3. The pup joint of claim 2, wherein the length of pipe, the male sub, and the female sub, and the retention shoulder are constructed of a single forging and the retention shoulder is machined into the male sub.

4. The pup joint of claim 1, wherein the male sub is threaded onto the distal end of the length of pipe, and the female sub is threaded onto the first end of the length of pipe.

5. A pup joint comprising:

a length of pipe having an outside diameter;

a female sub connected to a first end of the length of pipe, the female sub including a conical sealing surface, an outer surface formed adjacent the conical sealing surface and external threads formed on the outer surface;

a male sub connected to the distal end of the length of pipe, the male sub including a forward shoulder extending radially outwardly therefrom and a spherical sealing surface adjacent the forward shoulder which is adapted to mate with and seal against the conical sealing, surface of another such pup joint;

a nut having an internal surface, internal threads formed on the internal surface and a rearward shoulder extending radially inwardly from the internal surface;

one or more retainer segments positioned between the rearward shoulder of the nut and the forward shoulder of the male sub for restricting axial movement of the nut relative to the male sub in a first direction, the one or more retainer segments having an inside diameter greater than the outside diameter of the length of pipe;

a retainer ring positioned in a corresponding groove formed in the retainer segments and having an outer diameter which is greater than the diameter of the rearward shoulder to thereby maintain the nut positioned around the retainer segments; and

a non-removable retention shoulder extending radially outwardly from the male sub rearwardly of the forward shoulder, the retention shoulder comprising an outside diameter greater than the inside diameter of the retainer segments;

whereby the retention shoulder restricts axial movement of the nut and the retainer segments relative to the male sub in a direction opposite the first direction.

6. The pup joint of claim 5, wherein the male sub and the female sub are formed integral with the length of pipe.

7. The pup joint of claim 6, wherein the length of pipe, the male sub, the female sub, and the retention shoulder are constructed of a single forging and the retention shoulder is machined into the male sub.

8. The pup joint of claim 5, wherein the male sub is threaded onto the distal end of the length of pipe, and the female sub is threaded onto the first end of the length of pipe.

9. A pup joint comprising:

a length of pipe having an outside diameter;

a female sub connected to a first end of the length of pipe, the female sub including a conical sealing surface, an outer surface formed adjacent the conical sealing surface and external threads formed on the outer surface;

a male sub connected to the distal end of the length of pipe, the male sub including a section having, an outside diameter greater than the outside diameter of the length of pipe, the male sub also including a forward shoulder extending radially outwardly therefrom and a spherical sealing surface adjacent the forward shoulder which is adapted to mate with and seal against the conical sealing surface of another such pup joint;

a nut having an internal surface, internal threads formed on the internal surface and a rearward shoulder extending radially inwardly from the internal surface;

one or more retainer segments positioned between the rearward shoulder of the nut and the forward shoulder of the male sub for restricting axial movement of the nut relative to the male sub in a first direction;

a retainer ring positioned in a corresponding groove formed in the retainer segments and having an outer diameter which is greater than the diameter of the rearward shoulder to thereby maintain the nut positioned around the retainer segments; and

a non-removable retention shoulder extending radially outwardly from the section of the male sub, the retention shoulder positioned rearwardly of the forward shoulder, the retention shoulder comprising an outside diameter greater than the inside diameter of the retainer segments, the outside diameter of the retention shoulder also being greater than both the outside diameter of the length of pipe and the outside diameter of the section of the male sub;

whereby the retention shoulder restricts axial movement of the nut and the retainer segments relative to the male sub in a direction opposite the first direction.

10. The pup joint of claim 9, wherein the male sub and the female sub are formed integral with the length of pipe.

11. The pup joint of claim 10, wherein the length of pipe, the male sub, the female sub and the retention shoulder are constructed of a single forging and the retention shoulder is machined into the male sub.

12. The pup joint of claim 9, wherein the male sub is threaded onto the distal end of the length of pipe, and the female sub is threaded onto the first end of the length of pipe.