ALIGNED AND AXIALLY LOADED PIG INJECTOR VALVE, THREADED CONNECTION AND METHOD FOR CONNECTING THREADED MEMBERS

Abstract

A threaded connection comprising a first threaded member threadably connected with a second threaded member and an axial loading member. The first threaded member defines an opening for passage of the axial loading member therethrough, wherein the axial loading member protrudes from the first threaded member when in an extended position. The second threaded member has a loading surface defining a recess therein for receipt of the axial loading member when in the extended position such that the axial loading member bears on the loading surface and imparts an axial tensile force between the first and second threaded members. A method for connecting the members includes threading together the first and second threaded members, and passing the axial loading member through the opening defined by the first threaded member, so as to bear on the second threaded member within the recess, imparting the axial tensile force between the threaded members.

Description

FIELD OF INVENTION

The present invention relates to a method and apparatus for connecting two threaded members, and in particular, to a method and apparatus for axially loading the mated threads of a valve flange and a valve body while maintaining alignment of the bolt holes of the flange on a tubular member with the bolt holes of the valve flange.

BACKGROUND OF INVENTION

A typical pipeline valve is equipped with one or more flanges. The purpose of the flanges is to allow the connection of the valve to another flanged valve, to a flanged pipe or to a flanged fitting. To enable the flange of the valve to be attached to the mating valve of the applications described above, the bolt holes on the mating flanges must be geometrically aligned.

In valve designs where it is necessary to attach the valve flange to a valve body by means of a screw thread, it is not always possible to ensure that the valve flange can be fastened to the valve body such that the boltholes of the valve flange are in the correct geometrical alignment. It is normal to apply torque to the valve flange such that an axial loading is applied through the mating threads in order to prevent the threaded connection from becoming loose. However, when the valve flange is screwed on tight to the valve body, the boltholes of the valve flange may not be correctly aligned.

One existing approach to the problem is to incorporate a disc type spring such that as the mating threads are screwed together, the disc spring is compressed and this provides the axial loading on the mating threads while allowing a limited rotation of the mating threaded connection in order to bring the valve flange bolt holes into the correct alignment.

Another approach to this problem is to design a deformable feature into either the valve flange or the valve body such that as the valve flange is screwed into the valve body, where the deformable feature imparts an axial loading to the mating threaded connection while allowing a limited amount of rotation of the mating threaded connection in order to bring the valve flange bolt holes into the correct alignment.

In both of the previously described approaches, axial loading is applied to the mating threads when the spring or deformable feature comes into effect. Therefore, the axial loading applied to the mating threads is affected by the need to achieve geometrical alignment of the valve flange boltholes. Further, the resistance to rotation of the valve flange relative to the valve body is determined by the frictional resistance of the mating faces and the mating threads.

What is needed is an apparatus for applying an axial load to the mated threaded connection of a valve flange and valve body whilst permitting geometrical alignment of the bolt holes in the valve flange and providing non-frictional resistance to rotation, that overcomes the problems in the existing art.

SUMMARY OF INVENTION

The present invention relates to a method for connecting two threaded members of which one or both have a flange, and in particular, connecting a valve fitting with a tubular member having an attachment flange. In a preferred embodiment, the valve fitting is a pig injection valve for connection in a pipeline.

In one aspect, the invention comprises a method for connecting a first threaded member with a second threaded member, of which one or both threaded members includes a flange, comprising the step of passing an axial loading member through an opening defined by one of the two threaded members, so as to bear on the other threaded member, imparting an axial tensile force between the two threaded members.

In another aspect, the invention comprises a method of attaching a tubular member having an attachment flange defining a plurality of bolt holes to a valve fitting having a longitudinal axis for connection with a tubular member having an attachment flange, the fitting comprising:

• • a valve body having an outlet, a threaded end and a loading surface; and
  • a valve flange comprising a first threaded end for engaging the valve body threaded end, a flange for engaging the tubular member attachment flange, said flange defining a plurality of bolt holes, and a plurality of axial loading members each movable between a first position retracted away from the loading surface and a second extended position protruding to bear on the valve body loading surface to impart an axial tensile force between the valve body and valve flange;
    wherein the method comprises the steps of:
  • (a) threading the valve flange onto the valve body;
  • (b) rotating the valve flange until the bolt holes on the flange of the valve flange are geometrically aligned with the bolt holes on the attachment flange of the tubular member; and
  • (c) moving the axial loading member into its second extended position so that it bears on the loading surface of the valve body.

In another aspect, the invention may comprise a valve fitting having a longitudinal axis for connection with a tubular member having an attachment flange, the fitting comprising:

• • (a) a valve body having an outlet, a threaded end and a circumferential loading surface at a substantially right angle to the longitudinal axis of the fitting; and
  • (b) a valve flange comprising a first threaded end for engaging the valve body threaded end, a flange for engaging the tubular member attachment flange, and a plurality of axial loading members each movable between a first position retracted away from the loading surface and a second extended position protruding to bear on the valve body loading surface to impart an axial tensile force between the valve body and valve flange.

In another aspect, the invention may comprise a valve fitting apparatus having a longitudinal axis for connection with a tubular member having an attachment flange, the fitting comprising:

• • (a) a valve body having a threaded end defining an outlet, and a loading surface; and
  • (b) a valve flange comprising a threaded end engaging the valve body threaded end, a flange for engaging the tubular member attachment flange, and an axial loading member movable between a first position retracted away from the loading surface and a second extended position protruding to bear on the valve body loading surface to impart an axial tensile force between the valve body and valve flange.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described by means of an exemplary embodiment as shown in the accompanying, simplified, diagrammatic, not to scale drawings. In the drawings:

FIG. 1 is a cross sectional side view of one embodiment of the present invention.

FIG. 2 is a cross sectional perspective view of one embodiment of the present invention.

FIG. 3 is a diagrammatic depiction illustrating the alignment of the bolt holes of mating flanges of one embodiment of the present invention.

FIG. 4 is a diagrammatic depiction of the axial loading member of one embodiment of the present invention.

DETAILED DESCRIPTION

As used herein, any reference to “a” or “an” element shall not be construed to mean ‘only one’ unless it is expressly stated to do so.

As used herein, a “pig” means a device that moves through the inside of a pipeline for the purpose of cleaning, dimensioning, or inspecting.

The invention will now be described having reference to the accompanying figures. In a basic form, the invention may apply to any threaded connection between two members, to resist uncoupling of the two members or unwanted movement between the two members and to align the two members. In one embodiment, the invention has particular relevance to valve fittings within pipelines, as described below.

As depicted in FIGS. 1 and 2, the apparatus comprises a valve fitting (10) having a valve flange (20) and a valve body (12). In a preferred embodiment, the valve fitting is a pig injection valve as shown in the Figures. Accordingly, the valve body (12) has an outlet at each end which are both threaded (16). The threaded outlets each attach to a valve flange (20). However, the valve body (12) may have any number of threaded outlets depending on the type of valve fitting. For example, a ‘T’ valve fitting may have three threaded outlets, and a cross valve fitting may have four threaded outlets. The valve body (12) also has at least one loading surface (18) used to axially load the threaded connection between the valve body (12) and the valve flange (20) as described below. In a preferred embodiment, the loading surface is a circumferential shoulder which is substantially at a right angle to the longitudinal axis of the valve fitting.

The valve flange (20) comprises a flange (24), a threaded end (22) that engages the threaded end of the valve body (12), and at least one axial loading member (26). Suitable seals such as O-rings may be provided between the valve flange (20) and the valve body (12) as is well known in the art.

In a preferred embodiment, there are a plurality of axial loading members. The axial loading member (26) is movable between a first position whereby it is retracted away from the loading surface when the valve flange is connected to the valve body, and a second position where it protrudes to bear upon the loading surface (18). In a preferred embodiment, the axial loading members are substantially parallel to the longitudinal axis of the valve fitting and move along a parallel axis.

The flange (24) on the valve flange (20) defines a series of bolt holes (34) that correspond geometrically with bolt holes on the flange of the tubular member (44) to which the valve fitting (10) is being connected. FIG. 3 illustrates the required alignment of the connectors, or bolt holes, in the flange of the tubular member (44) with those bolt holes in the valve flange (20).

In one embodiment the axial loading member (26) is housed within a passage (32) in an abutment of the valve flange (20). The interior surface of the passage (32) and the exterior surface of the axial loading member (26) may be configured with complementary threads (not shown in the diagrams) so that the axial loading member (26) can be moved into its second extended position by rotating it within the passage (32). The axial loading member (26) may be a set screw, however such other means as are commonly used to retract and extend members in the art may be utilized.

In a preferred embodiment, the set screws (26) may have a tapered point and the loading surface (18) on the valve body (12) defines a number of recesses (30) to receive the set screws (26) when extended into their second extended position. It should be understood that a plurality of axial loading members, loading surfaces and recesses can be utilized with the present invention. Accordingly, when the set screws are extended and engaged in the recesses, it will be apparent that the set screws impart an axial tensile force between the valve body (12) and the valve flange (20). As well, the valve body and the valve flange cannot be rotated relative to each other without shearing the set screws. As used herein, an “axial tensile force” is a force which tends to separate the valve body and the valve flange, along their longitudinal axes.

Once the threads of the valve flange (20) and the valve body (12) have been engaged, the axial loading member (26) is moved into its second extended position so that it protrudes into the recess (30) and bears on the loading surface (18). As torque is applied to the axial loading member (26), a resulting axial tensile force is applied between the valve body (12) and the valve flange (20). In other words, the axial loading members impart a force tending to separate the valve body (12) and the valve flange (20). This results in an axial loading being applied through the mated threads of the valve flange (20) and the valve body (12). Thus, unwanted loosening of the mated threads is prevented by the extended axial loading member (26) and friction in the threaded connection. Once the flange (24) is aligned with the pipeline flange, the threaded connection between the valve body and the valve flange can be axially loaded without further rotation of the valve flange.

In a preferred embodiment, the axial loading member (26) comprises a conical point screw housed in a passage (32), and the use of a conical shaped recess (30) in the loading surface (18). The end of the conical point screw mates with the conically shaped recess (30) on the loading surface (18) ensuring that each axial loading member (26) contributes to axial loading and also shear resistance to rotation. FIG. 4 is a diagrammatic depiction of a conical point screw suitable for use with the present invention. A specified amount of torque may be applied to each axial loading member (26) to attain an appropriate amount of axial loading.

The valve fitting (10) may be a ball valve, or such other suitable valve fitting as would be selected by one skilled in the art. As depicted in FIG. 2, the valve fitting may be suitable for use for inserting or extracting pigs from a pipeline, and may be a pig injector valve having an aperture (42) and a sealing cap (not shown).

The valve fitting (10) may be constructed from any suitable material including, without limitation, suitable metals or alloys thereof, or suitable plastic or composite materials.

The use of the invention will now be described having reference to FIGS. 1 and 2. The valve body (12) and the valve flange (20) are screwed together. The valve flange (20) is rotated until the bolt holes in the flange (24) are geometrically aligned with the bolt holes in the attachment flanges of the tubular member (44) that the valve fitting (10) is being attached to. One particularly effective method is to thread together the valve flange and the valve body until no further rotation is possible. The valve flange can then be reversed slightly until the bolt holes are aligned. With a typical bolt pattern of a pipeline attachment flange, this may be accomplished with less than a 90° turn.

The set screws (26) are then rotated, extending them into their second extended position whereby they bear upon the loading surface (18) of the valve body (12). Sufficient torque is applied to the set screws (26) to axially load the mated threads enough that the threads become frictionally engaged. The flange (24) on the valve flange (20) and the attachment flange on the tubular member (44) are then bolted together. Alternatively, the flanges may be bolted together before the axial loading members are extended into their second position. This process is repeated if the valve fitting (10) has a second threaded end for attachment to a second tubular member.

As will be apparent to those skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the scope of the invention claimed herein. The various features and elements of the described invention may be combined in a manner different from the combinations described or claimed herein, without departing from the scope of the invention.

Claims

1. A method for connecting a first threaded member with a second threaded member, one or both of which include a flange, comprising:

(a) threading together the first and second threaded members;

(b) passing an axial loading member through an opening defined by the first threaded member, so as to bear on the second threaded member within a recess defined by a loading surface of the second threaded member, imparting an axial tensile force between the two threaded members.

2. The method of claim 1 wherein the axial loading member is a set screw.

3. The method of claim 2 wherein the set screw engages the first threaded member in a threaded opening having a longitudinal axis substantially parallel to a longitudinal axis of the first threaded member.

4. The method of claim 1 wherein the axial loading member has a tapered end for receipt in the recess.

5. The method of claim 1 wherein the recess is conical.

6. The method of claim 5 wherein the axial loading member has a tapered end for receipt in the recess.

7. The method of claim 1 wherein the axial loading member is substantially parallel to a longitudinal axis of the first threaded member.

8. The method of claim 6 wherein the axial loading member is substantially parallel to a longitudinal axis of the first threaded member.

9. A threaded connection comprising:

(a) an axial loading member movable between a first retracted position and a second extended position;

(b) a first threaded member defining an opening for passage of the axial loading member therethrough, wherein the axial loading member protrudes from the first threaded member when in the second extended position;

(c) a second threaded member threadably connected with the first threaded member, wherein the second threaded member has a loading surface defining a recess therein for receipt of the axial loading member when in the second extended position such that the axial loading member bears on the loading surface and imparts an axial tensile force between the first threaded member and the second threaded member.

10. The threaded connection of claim 9 wherein the axial loading member has a tapered end for receipt in the recess.

11. The threaded connection of claim 9 wherein the recess is conical.

12. The threaded connection of claim 11 wherein the axial loading member has a tapered end for receipt in the recess.

13. The threaded connection of claim 12 wherein the axial loading member is substantially parallel to a longitudinal axis of the first threaded member.

14. The threaded connection of claim 9 wherein the axial loading member comprises a set screw.

15. The threaded connection of claim 14 wherein the opening is threaded.

16. The threaded connection of claim 15 wherein the axial loading member is substantially parallel to a longitudinal axis of the first threaded member.