REPLACEMENT TUBE PLUG FOR HEAT EXCHANGER

Abstract

A replacement tube plug for sealing the threaded junction between a tube plug and a bore in a plugsheet, the tube plug including a body part having proximal and distal ends, an outer threaded surface, a central bore open at the proximal end and at least one branch bore extending from and in fluid communication with the central bore and extending radially to the outer surface of the body part, and a method for delivering fluid sealant via the central and branches to the threaded junction of the tube plug and the plugsheet.

Claims

1. A tube plug for sealing a threaded plug-to-plugsheet Junction, said tube plug comprising: a. a body part having length between proximal and distal ends and a threaded outer surface, b. a main internal passageway extending generally axially from said proximal end distally a distance less than the length of said body part, c. at least one branch passageway in fluid communication with said main passageway and extending radially outward to and through said outer threaded surface, thereby defining a continuous passageway open at said proximal end of said body part and open at said threaded outer surface of said body part, and d. a cap positionable to close said proximal end opening of said main passageway.

2. The tube plug according to claim 1 wherein said at least one branch passageway comprises a plurality of branch passageways that are axially spaced apart relative to each other lengthwise of said body part.

3. The tube plug according to claim 1 wherein said at least one branch passageway comprises a plurality of passageways which extend in different outward directions circumferentially spaced from each other.

4. The tube plug according to claim 1 wherein said at least one branch passageway comprises a plurality of branch passageways which are axially spaced apart from each other lengthwise of said body part and which extend in different outward directions circumferentially spaced from each other.

5. The tube plug according to claim 1 wherein said at least one branch passageway comprises: (i) a first branch passageway, (ii) a second branch axially spaced apart from said first branch passageway, and (iii) a third branch passageway axially spaced from both said first and second branches, where all three branch passageways are circumferentially spaced apart 120 from the each other.

6. The tube plug according to claim 1 wherein said main passageway is situated centrally of said body part, and said at least one branch passageway extends radially outward at an angle about 90 from said main passageway.

7. The tube plug according to claim 1, wherein said body part has a maximum outer diameter D1 along its length, and further comprises a head part integral with said proximal end of said body part, and having diameter D2 greater than said diameter Dl.

8. A method of converting a standard solid externally threaded tube plug having proximal and distal ends along its length, into a replacement tube plug adapted to deliver fluid sealant to the region of mating threads between said tube plug threaded into a plugsheet, comprising the steps: a. drilling a central bore hole axially through said proximal end in the distal direction a distance less than the length of said solid tube plug, b. drilling at least one branch duct radially inward from said outer surface threaded region to intersect said central bore hole, thereby defining a continuous passageway open at said proximal end of said body part and open at said threaded outer surface, and c. forming threads at said proximal end of said central bore hole to receive a screw to close and seal said proximal end of said bore hole.

9. A method of directing fluid sealant to the region of mating threads between a tube plug screwed into a bore of a plugsheet by modifying a standard solid tube plug which has proximal and distal ends, comprising the steps: a. forming threads in said bore of said plugsheet corresponding to the external threads on said tube plug, b. drilling in said solid tube plug a central internal passageway extending from the proximal end and a distal direction a distance less than the length of said tube plug, c. drilling at least one branch duct from said outer thread region radially inward to and intersecting said central internal passageway, and d. forming threads in the proximal end of said central passageway adapted to receive a screw to close said passageway.

10. The method according to claim 9 where drilling said at least one branch duct comprises drilling three branch passageways axially spaced apart lengthwise of said tube plug body part and circumferentially spaced apart each from the others.

11. The method according to claim 10 wherein said three branch ducts are oriented 120 from each other.

12. A method of directing fluid sealant to the region of mating threads between a tube plug screwed into a bore of a plugsheet forming a replacement tube plug according to claim 1, threaded the inserting said replacement tube plug into the bore of a plugsheet, directing fluid sealant through said passageways in said replacement tube to said threaded region between said replacement tube plug and bore of said plugsheet, and closing said main passageway.

Description

IV. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is and elevation view of a prior art he exchanger installation,

[0021] FIG. 2 is an enlarged fragmentary view of a prior art tube plug installed in a plugsheet of FIG. 1,

[0022] FIG. 3 is a perspective view showing the new tube plug,

[0023] FIG. 4 is a fragmentary elevation view in section showing the new tube plug installed in a plugsheet,

[0024] FIG. 5 is a sectional view taken along line 5-5 in FIG. 4 showing central and radial passageways in the tube plug,

[0025] FIG. 6 is a side elevation view of the new tube plug,

[0026] FIG. 7 is a distal end elevation view thereof,

[0027] FIG. 8 is a proximal end elevation view thereof, and

[0028] FIG. 9 is a sectional view taken along line 9-9 in FIG. 6 showing internal central and radial passageways.

[0029] Features of the invention will become apparent from the following description of the exemplary embodiments taken in conjunction with the accompanying drawings.

V. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] For convenience and clarity in describing these embodiments, similar elements or components appearing in different Figures will have the same reference numbers.

[0031] FIG. 1 shows schematically a prior art air cooled heat exchanger (ACHE) 1 with multiple rows of heat exchange tubes 2A, 2B, 2C, etc., having fins 3 along their length. These heat exchange tubes extend between the opposite tubesheets 4A, 4B which are supported in frame 6. The ends 10 of the heat exchange tubes are mounted in the tubesheets 4A, 4B, and are in fluid communication indicated by arrows 5 with inlet and outlet manifolds (headers) 8A, 8B respectively. Outward of tubesheets 4A, 4B are plugsheets 4C, 4D. The finned outer surfaces of the respective heat exchange tubes are exposed to ambient air which may move by natural convection or may be exposed to forced air flow indicated by arrow 14 (fans or blowers not shown).

[0032] FIG. 2 is a fragmentary enlarged view of a prior art tube plug 20 whose outer surface 22 is threaded and engages mating threads 24 in the aperture 26 in plugsheet 4C. Damage to threads 24 on tube plug 20 or threads 26 in plugsheet 4C are the principal subject of the present invention, as it is these threads which become damaged when a tube plug 20 is forcibly removed for maintenance or other purposes. Threaded surfaces often become galled and may be seriously damaged when removed, such that they can longer provide a fluid tight seal when re-installed.

[0033] FIGS. 3-9 illustrate a new tube plug 40 of the present invention which has head or flange 41, stem or body 42 and central passageway 43. As seen in FIG. 4 tube plug 40 has length L2 of passageway 43 less than the total length L1 of the tube plug and diameter D1 of body 42 less than diameter D2 of tube plug head 41. FIGS. 4, 5 and 7-9 illustrate how branch passageways 44 intersect central passageway 43 and extend radially outward to the threaded region. FIG. 4 also shows how the three passageways 44 are axially spaced apart along the length of the tube plug stem or body part 42. FIGS. 5 and 7-9 show how passageways 44 are displaced 120 circumferentially from each other. These branch passageways 44 as illustrated, extend at 90 from central passageway 43, but they may extend at other angles or along other paths. This array of branch passageways allows a wide distribution area of fluid sealant 56 along and around the threads to achieve a reliable seal. Many commercial sealants are available, one example being a product sold under the label XX Heavy Sealant #5050 by Sealweld Corporation, Calgary, Alberta, Calif. Tube plug threads 52 engaged plugsheet threads 54, and sealant 56 as shown is forced into areas of damaged threads; however, sealant will not flow into regions of undamaged and tight thread engagement.

[0034] Also seen in FIG. 4, after the sealant 56 is injected through central passage 43, cap screw 46 is threaded into the proximal end of passageway 43 to block escape of sealant and to block inlet of debris. Cap screw 46 may serve the additional purpose when screwed end, of pushing or compressing sealant 56 to flow in central passage 43 and thence out through branch passages 44.

[0035] While the invention has been described in conjunction with several embodiments, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications, and variations which fall within the spirit and scope of the appended claims.