Stabilized tap mounting assembly

Abstract

A method and apparatus are directed to reduce the load from the threads on taps on an orifice plate or orifice fitting. The apparatus includes a tap (3) having an NPT threaded end (1) and a flanged end (12) and an intermediate flange (13) which engages with a stabilizing tube (2) placed around the tap (3). In use, a stabilizing nut (1), previously threaded on the stabilizing tube (2), is unthreaded thereby forcing the stabilizing tube (2) against the intermediate flange (13) and transferring at least some of the weight off the threads (1) of the tap (3).

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the remote sensing of pressure drops across an orifice plate in a pipeline and particularly to a stabilized tap mounting assembly to facilitate, stabilize and reduce vibration of the transmitter and associated apparatus, such as valved manifold blocks connecting the transmitter to taps on an orifice plate or orifice fitting.

2. Description of the Related Art

The gas industry makes extensive use of orifice plates for volume measurements. Orifice plates are artificial constrictions in a pipeline. As a result of this constriction, there is a pressure drop from the upstream side of the orifice plate to the downstream side of the orifice plate. There is a relationship between the pressure drop and the amount of gas flowing through the pipeline. The pressure drop can be measured, which in turn allows a determination of the flow through the pipeline.

The pressure drop is measured using electronic transmitters. These transmitters actually measure the pressures on both the upstream and downstream sides of the orifice plate and then record the difference between the two. Devices of this type are referred as differential pressure transmitters. There are numerous manufacturers of this type of device (e.g., Rosemount, Honeywell, Foxboro and others).

Orifice plate fittings (such as the type manufactured by Daniel Industries) and orifice flanges (manufactured by Daniel and others) are provided with holes (called taps) both upstream and downstream of the orifice plate. The taps are generally threaded holes, typically ½″ female NPT (National Pipe Thread—a tapered thread designed to seal pressure tight).

It is necessary to incorporate valving systems between the orifice taps and the differential pressure transmitters. These valving systems need to include the following functions. Block valves to isolate the flow through the upstream and downstream taps (generally referred to as the high pressure side and the low pressure side), between the orifice flange or fitting and the transmitter. An equalizer valve, or valves, to control the connection between the high pressure passages and the low pressure passages. A vent valve, or valves, to allow trapped pressures to be bled off or to allow the passages to be purged of entrapped gases or liquids. Sometimes the vent valve(s) are incorporated into the transmitters.

The natural gas industry has evolved a number of specifications and requirements to minimize errors in the measurement of flow and to provide improved accuracy and response time. Some of these are:

• • 1. The closer the transmitter is to the orifice plate the better.
  • 2. The orifice size through the valving system from the orifice taps to the transmitter must be ⅜″ in diameter.
  • 3. The flow passages between the orifice taps to the transmitter should be as straight as possible. The ideal is a straight through passage. One 90 degree turn in the flow passage is permitted.

Another consideration is mounting the valve system and the transmitters to the orifice plate assembly. Conventional mounting, valving, and transmitter assemblies can weigh 40 pounds and, depending on the complexity of the assembly and the products used, up to 70 pounds. The pipeline system and the orifice flanges or fittings are subject to vibration. The valving and transmitter assemblies also tend to be leaned on by the instrumentation personnel.

Thus, there is a continuing need to provide an alternative connection method and apparatus to operatively fluidly couple the high and lower pressure taps about an orifice plate with a transmitter.

SUMMARY OF THE INVENTION

The device of the invention has been developed to provide a stabilized mount to permit conventional manifold/transmitter assemblies to be attached to orifice fittings. The novelty of this device is restricted to the stabilizing mount itself. The manifold shown in the attached drawings is commercially available through Century Valve and Machine of Calgary, Alberta, Canada and others.

The stabilized tap assembly is designed to mount to both orifice fittings (as manufactured by Daniel and others) as well as orifice flanges.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a typical transmitter and block manifold assembly for use with the stabilizing taps of the invention;

FIG. 2 is a schematic assembled view of the taps of the invention with a conventional manifold;

FIG. 3 is an enlarged view of the taps of the invention of FIGS. 1 and 2 to show detail thereof;

FIG. 4 is a schematic side view of the stabilizing tube of FIGS. 1-2;

FIG. 5 is a top view of the stabilizing tube of FIG. 4;

FIG. 6 is a section along A-A of FIG. 4 of the stabilizing tube;

FIG. 7 is a schematic cross section of a flange shoe for use in mounting the tap of the invention on an orifice flange; and

FIG. 8 is a cross sectional assembled view of the tap and flange shoe on an orifice flange.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

There are two tap assemblies required for each manifold (4) installation. Each tap assembly consists of three pieces. The tap (3), the stabilizing tube (2) and the stabilizing nut (1). The tap consists of a male NPT threaded end (1) and a flanged end (12). The flanged end (12) is for attachment to a conventional manifold (4). The tap (3) also includes a stabilizing flange (13) which is integral with the tap (3) and which is located between the NPT thread end (10) and the manifold connection flanged end (12).

The tap (3) is installed as follows. The stabilizing tube (2) and the stabilizing nut (1) are threaded together. The tap (3) is inserted through bore (14) in the stabilizing tube (2) and the stabilizing nut (1). The tap (3) is threaded into the orifice fitting (5). One end of the stabilizing tube (2) has a flat surface (15) with two projections (16)(17). These two projections (16)(17) fit into mating recesses (18)(19) on the stabilizing flange (12) located on the tap (3). The stabilizing nut (1) is turned on the stabilizing tube (2). The projections (16)(17) on the stabilizing tube (2) prevent the stabilizing tube (2) from turning relative to the tap (3). The lower end of the stabilizing nut (1) is forced against the orifice fitting (5) while the upper end of the stabilizing tube (2) is forced against stabilizing flange (12) on the tap (3). When the assembly of stabilizing nut (1) and stabilizing tube (2) is placed in compression, the loads are transferred from the NPT threads of tap (3), via the stabilizing flange (12), onto the stabilizing tube (2) and stabilizing nut (1), which in turn bears on the orifice fitting (5).

Precision General Inc. (PGI) manufactures a stabilized futbol device, which is covered by their patent U.S. Pat. No. 4,920,626. In PGI's device the tap itself is threaded and the jam nut threads directly onto the tap.

In the invention, the stabilized tap assembly transfers the imposed loads through a larger area (the stabilizing flange), rather than just threads on the tap. As a result, there are lower stresses imposed on our tap rather than on PGI tap threads.

The same stabilized tap assembly can be used with orifice flanges (30) (instead of the orifice taps of FIG. 1) by using a flange shoe (20) (FIG. 7). The flange shoe (20) is shown on the cross sectional view of FIG. 8. The device works the same as described above except that the stabilizing nut (1) bears on the flange shoe (20). The flange shoe has two projections (22)(24) along opposite sides. Those projections are rounded, as shown on the drawings, and those projections bear on the flange. The flange shoe can be designed to fit all flange sizes and ratings.

It will be apparent to those skilled in the art that many modifications can be made to the invention without departing from the spirit or scope of the appended claims.

Claims

1. A tap assembly that attaches at least one of a manifold and pressure transmitter to an orifice, the tap assembly comprising: (a) a tap comprising a male NPT threaded end that connects with the orifice and a flanged end that connects with the at least one of the manifold and pressure transmitter; (b) a separate stabilizing tube disposed between the threaded end and flanged end, the stabilizing tube having an external thread; and (c) a stabilizing nut threaded on the stabilizing tube.

2. The tap assembly of claim 1, wherein the tap is further provided with a stabilizing flange.

3. The tap assembly of claim 2, wherein the stabilizing flange is provided intermediate the threaded end and flanged end.

4. The tap assembly of claim 2, wherein the stabilizing tube has at least one projection interfitting with a recess in the stabilizing flange.

5. The tap assembly of claim 4, wherein the at least one projection comprises two projections interfitting with two mating recesses in the stabilizing flange.

6. The tap assembly of claim 1, further comprising a manifold connected to the flanged end of the tap.

7. The tap assembly of claim 1, further comprising a pressure transmitter connected to the flanged end of the tap.

8. The tap assembly of claim 6, further comprising a pressure transmitter connected to the manifold.

9. The tap assembly of claim 1, further comprising a flange shoe.

10. The tap assembly of claim 1, wherein the tap comprises an elongated member having an internal bore extending along an axis through the elongated member from the threaded end to the flanged end to define a passage that permits fluid communication between the orifice and the at least one of a manifold and pressure transmitter.

11. The tap assembly of claim 10, wherein the internal bore comprises a straight passage.

12. The tap assembly of claim 10, wherein the flanged end comprises at least one aperture that connects the tap assembly to the manifold via a threaded fastener.

13. The tap assembly of claim 12, wherein the flanged end comprises a generally rectangular member having the at least one aperture extending generally orthogonally the axis of the internal bore of the tap.

14. The tap assembly of claim 13, wherein the at least one aperture comprises a slot having a closed end proximate the passage and an opened end distal thereto.

15. The tap assembly of claim 4, wherein the stabilizing flange circumscribes the elongated member and has at least one recess disposed proximate an outer perimeter of the stabilizing flange.

16. The tap assembly of claim 15, wherein the separate stabilizing tube comprises a generally tubular member having a bore extending from a first end to a second end to define a passageway, and an outer surface that consists of a first portion with a flat surface that engages the stabilizing flange, the first surface having a first diameter, and a second portion with a second diameter, the first diameter being greater than the second diameter.

17. The tap assembly of claim 16, wherein the separate stabilizing tube further comprises at least one projection that extends away from the flat surface, the at least one projection being configured to mate with the at least one recess of the flanged portion of the tap.

18. The tap assembly of claim 17, wherein the orifice is selected from a group consisting of an orifice plate and orifice flange.

19. A tap assembly that attaches at least one of a manifold and pressure transmitter to an orifice, the tap assembly comprising: (a) a tap defining a bore along an axis, a first end proximate the bore having a male NPT threaded end that engages the orifice, and a second end proximate the bore having a flanged end that engages the at least one of a manifold and pressure transmitter; (b) a first separate tubular member surrounding a portion of the bore and being disposed between the first end and the second end of the tap; and (c) a second separate tubular member surrounding a portion of the first tubular member and being disposed between the first end and the second end of the tap, the second tubular member defining a continuous gap between an inner surface of the second tubular member and an outer surface of the tap.

20. The tap assembly of claim 19, wherein the tap comprises a male NPT threaded end and a flanged end.

21. The tap assembly of claim 20, wherein the first separate tubular member is disposed on the tap between the male NPT threaded end and flanged end.

22. The tap assembly of claim 21, wherein the second separate tubular member comprises a nut with an inner surface that defines the continuous gap.

23. The tap assembly of claim 22, wherein the bore of the tap defines a straight passage that permits fluid communication between the orifice and the at least one of a manifold and pressure transmitter.

24. The tap assembly of claim 23, wherein the flanged end comprises at least one aperture that attaches the tap assembly to at least one of the manifold and pressure transmitter via a threaded fastener.

25. The tap assembly of claim 24, wherein the flanged end comprises a generally rectangular member having the at least one aperture extending generally orthogonally with respect to the bore of the tap, the aperture having a closed end proximate the passage and an opened end distal thereto.

26. The tap assembly of claim 19, wherein the tap comprises a stabilizing flange portion circumscribing the bore and disposed between the threaded end and the flanged end, the stabilizing flange portion having at least one recess disposed proximate the outer perimeter of the stabilizing flange portion.

27. The tap assembly of claim 26, wherein the first separate tubular member comprises a generally tubular member having a bore extending from a first end to a second end to define a passageway, and an outer surface that engages the stabilizing flange that consists of a first portion with a flat surface having a first diameter and a second portion with a second diameter, the first diameter being greater than the second diameter.

28. The tap assembly of claim 27, wherein the second separate tubular member comprises a stabilizing nut having a surface that engages a surface proximate the orifice.

29. The tap assembly of claim 28, wherein the first separate tubular member comprises at least one projection that extends away from the flat surface toward the flange end of the tap, the at least one projection being configured to mate with the at least one recess of the flanged portion of the tap.

30. The tap assembly of claim 19, further comprising a flange shoe having a first surface contiguous to a surface of the second separate tubular member and a second surface that engages an area proximate the orifice.

31. A tap assembly that attaches at least one of a manifold and pressure transmitter to an orifice, the tap assembly consisting essentially of: (a) a tap having an exterior surface, a male NPT threaded end, and a flanged end; (b) a separate stabilizing tube having an internal bore contiguous the exterior surface of the tap and an outer surface with external threads; and (c) a stabilizing nut threaded on the external threads of the separate stabilizing tube.

32. The tap assembly of claim 31, wherein the tap defines a straight passage that permits fluid communication between the orifice and the at least one of a manifold and pressure transmitter, the flanged end of the tap having at least one aperture that allows the tap assembly to be secured to the at least one of the manifold and pressure transmitter via a threaded fastener and the flanged end having a generally rectangular member having the at least one aperture extending generally orthogonally with respect to the straight passage of the tap, the slot having a closed end proximate the passage and an opened end distal thereto, the tap having a stabilizing flange portion circumscribing the passage and disposed between the threaded end and the flanged end, the stabilizing flange portion having at least one recess disposed proximate the outer perimeter of the stabilizing flange portion.

33. The tap assembly of claim 31, wherein the separate stabilizing tube is a generally tubular member having a bore extending from a first end to a second end to define a passageway, and an outer surface that engages the stabilizing flange and consists of a first portion with a flat surface having a first diameter and a second portion with a second diameter, the first diameter being greater than the second diameter, the flat surface having at least one projection that extends away from the flat surface towards the flanged end of the tap, the at least one projection being configured to mate with the at least one recess of the flanged portion of the tap.

34. The tap assembly of claim 31, wherein the stabilizing nut comprises an inner surface that defines a continuous gap between the inner surface and a bottom flat surface generally orthogonal to the inner surface that engages a surface proximate the orifice.

35. A tap assembly that attaches at least one of a manifold and pressure transmitter to an orifice, the tap assembly comprising: (a) a tap including a male NPT threaded end, a flanged end, and bore extending between the male NPT threaded end and the flanged end; and (b) a load transfer member that surrounds the male NPT threaded end of the tap and engages a portion of the tap.

36. The tap assembly of claim 35, wherein the portion of the tap comprises a stabilizing flange.

37. The tap assembly of claim 35, wherein the load transfer member comprises a separate stabilizing tube.

38. The tap assembly of claim 36, wherein the load transfer member further comprises a stabilizing nut having internal threads engaging external threads of the separate stabilizing tube.

39. The tap assembly of claim 35, wherein the load transfer member further comprises a flange shoe that engages a surface proximate the orifice.

40. The tap assembly of claim 35, wherein the tap assembly consists of: the tap having a male NPT threaded end, a flanged end, and bore extending between the male NPT threaded end and the flanged end, and a stabilizing flange disposed between the male NPT threaded end and the flanged end; and the load transfer member that surrounds the tap proximate the male NPT threaded end of the tap and engages the stabilizing flange of the tap.

41. A method of attaching a tap to an orifice, the tap including a male NPT threaded end, a flanged end, the tap having a bore extending between the male NPT threaded end and the flanged end, the method comprising: disposing the threaded end of the tap in the orifice; surrounding a portion of the tap with a member; engaging a first end surface of the member with an area proximate the orifice; and abutting a second end surface of the member with the tap.

42. The method of claim 41, wherein the abutting comprises engaging the second end surface with a stabilizing flange of the tap, the stabilizing flange having an outer perimeter greater than a perimeter of the orifice.

43. The method of claim 42, wherein the disposing comprises threading the tap.

44. The method of claim 43, wherein the abutting comprises translating the tap in the first direction via a separate stabilizing tube.

45. The method of claim 44, wherein the translating comprises translating a first surface of the separate stabilizing tube with respect to a second surface of a separate stabilizing nut.

46. The method of claim 45, further comprising securing at least one of a manifold and pressure transmitter to the flanged end of the tap.

47. The method of claim 46, wherein the moving comprises moving a portion of a load applied to the tap to an area having a perimeter larger than an outer perimeter of the NPT threaded end of the tap.