Heat exchanger tube plug

Abstract

A heat exchange plug that plugs the aperture of a tubesheet with a leaking tube while also securing the tube against movement that could damage other tubes of the tubesheet. A cylindrical housing member with two different diameter body section can be inserted so that the wider diameter section is positioned in the aperture of the tubesheet and the smaller diameter section is located in the tube. An eccentric ring at the end of the housing member can engage the tube and prevent rotation as an insert member is advanced into the rear of the housing member via a threaded shank of the insert member that engages a threaded inner bore of the housing member. A ramped surface of the housing member deforms the wall of the larger diameter section of the housing member outwardly to plug the aperture while the smaller diameter section secures the tube in place.

Claims

1. A method of sealing a heat exchanger having a tubesheet and a plurality of tubes coupled to the tubesheet, comprising the steps of: positioning a heat exchanger tube plug in an aperture of a tubesheet so that a housing member of the heat exchanger tube plug has a first cylindrical body with a deformable wall of a first outer diameter positioned in the aperture and has a second cylindrical body extending from the first cylindrical body with a second outer diameter that is smaller than the first outer diameter that extends into and engages a tube of the tubesheet; and rotating an insert member of the heat exchanger tube plug relative to the housing member so that a threaded shank of the insert member engages an inner threaded bore of the second cylindrical body, thereby causing the insert member to advance into the housing member so that a ramped surface of the insert member deforms the deformable wall of the first cylindrical body outwardly into contact with the aperture of the tubesheet.

2. The method of claim 1, wherein the rotation of the insert member relative to the housing member causes an eccentric ring positioned on an end of the second cylindrical body of the housing member to engage the tube of the tubesheet and prevent rotation of the housing member while the insert member is being rotated.

3. The method of claim 2, wherein the insert member includes a driving recess allowing an external force to cause rotating of the insert member.

4. The method of claim 3, wherein the driving recess has a hexagonal geometry.

5. The method of claim 4, wherein the ramped surface of the insert member is formed integrally with the threaded shank.

6. The method of claim 4, wherein the ramped surface of the insert member is formed by a conical ferrule.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

(1) The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which:

(2) FIG. 1 is a side view of a heat exchanger tube plug according to the present invention;

(3) FIG. 2 is a cross-sectional view of a heat exchanger tube plug according to the present invention

(4) FIG. 3 is a side view of a housing member for a heat exchanger tube plug according to the present invention;

(5) FIG. 4 is a perspective view of a housing member for a heat exchanger tube plug according to the present invention;

(6) FIG. 5 is a side view of an insert member for a heat exchanger tube plug according to the present invention;

(7) FIG. 6 is a schematic of a heat exchange tubesheet and tubes in need of repair; and

(8) FIG. 7 is a schematic showing a heat exchanger tube plug according to the present invention installed in a tubesheet to plug the tube and support the tube against movement from its designed location in the tubesheet.

DETAILED DESCRIPTION OF THE INVENTION

(9) Referring to the figures, wherein like numeral refer to like parts throughout, there is seen in FIG. 1 a heat exchanger tube plug 10 made in accordance with the present invention. Plug 10 comprises a housing member 12 and an insert member 14 that can be advanced into housing member 12. Housing member 12 has first cylindrical body 16, the rear portion of which is formed with a large open bore 18. Bore 18 is surrounded by relatively thin wall 20 that is deformable and will expand outwardly to provide a seal with a cylindrical opening, such as the aperture of a tube sheet in response to advancement of insert member 14 into bore 18. For example, as seen in FIG. 1, wall 20 may be serrated or textured to encourage deformation. Housing member 12 includes a second cylindrical body 30 positioned on the opposing side of first cylindrical body 16 from bore 18. Second cylindrical body 30 has a smaller diameter than first cylindrical body 16 and includes a threaded bore 32 therein that is smaller than bore 18 and is in communication with bore 18. First cylindrical body 16 is dimensioned to fit securely within the aperture of a tube sheet with second cylindrical body 30 extending into the tube that is associated with that aperture of the tube sheet. Housing member 12 thus has a stepped design with the larger portion dimensioned to fit in the aperture of the tubesheet and the smaller portion fitting in the tube to be sealed.

(10) Housing member 12 includes an eccentric assembly 34 coupled to the end of second cylindrical body 30 so that second cylindrical body 30 is locked against rotation when second cylindrical body 30 and eccentric assembly 34 are inserted through an aperture of a tubesheet and then into the tube associated with the aperture of the tubesheet. For example, eccentric assembly 34 may comprise a cylindrical post 36 that extends axially from second cylindrical body 30, and a ring member 38 mounted eccentrically to post 36 relative to a longitudinal axis X-X of housing member 12 and rotatable thereon.

(11) Insert member 14 comprises a head 40 and a tapered ferrule 42, which is preferably frustoconical. Head 40 preferably includes a driving recess 44 formed therein, such as a hex socket head manual rotation of insert member 14 using a hex driver, but other coupling approaches may be used. Ferrule 42 is dimensioned to fit inside the aperture of a tubesheet having a tube to be plugged, and to be slightly larger than bore 18. Insert member 14 includes a threaded shank 46, such as a threaded shaft extending from head 40 through tapered ferrule 42, that can extend inside and engage threaded bore 32. Although head 40 and shank 46 are show as separate structures from ferrule 42, the components could also be integrally formed as a single unit.

(12) Rotation of head 40, and the locking of second cylindrical body 30 against rotation by eccentric assembly 34 in tube, will cause insert member 14 to advance into housing member 12 by the cooperation of threaded shank 46 and threaded bore 32. Advancement of insert member 14 causes ferrule 42 to engage wall 20 and then to deform wall 20 outwardly, thereby engaging the inner surface of a tubesheet aperture. Housing member 12 thus seals the aperture of the tubesheet while second cylindrical body 30 remains fixed within the tube associated with that aperture of tubesheet. As a result, the tube is fixed against movement and cannot sag, separate, or drop to interfere with or damage the other tubes connected to the tubesheet. Heat exchanger tube plug 10, when installed into compression against the tubesheet, creates a mechanical contact seal capable of withstanding up to 7,000 psi.

(13) Tube plug 10 preferably expands approximately 30 mils (0.030″) to provide a positive seal and thus first cylindrical body 16 can easily be dimensioned accordingly based on the inner dimensions of tubesheet aperture 52. Similarly, second cylindrical body 30 may be dimensioned to slide into the tube associated with the tubesheet aperture 52. For example, the outer diameter of first cylindrical body 16 is dictated by the size of tubesheet aperture 52, and the outer diameter of second cylindrical body 30 is dictated by the inside diameter of the tube 54 (which is typically the diameter of tubesheet aperture 52 less two times the thickness of the wall of tube 54 ). Tube 54 thicknesses can range significantly, with the various wall thicknesses from 10 to 24 BWG (boiler wall gauge). Plug 10 thus would have first cylindrical body 16 with an outer diameter of equal to the outside diameter of tube 54 (the outside diameter of tube 54 is very close to or about the same as the inner diameter of tubesheet aperture 52) and second cylindrical body 30 would depend on the inner diameter of the particular tube 54. Exemplary dimensions common in the field are listed in Table A below:

(14) TABLE-US-00001 TABLE A Wall Thickness Tube Outside Diameter (inches) BWG (inches) 0.500 0.625 0.750 0.875 1.000 1.250 1.500 1.750 2.000 10 0.134 0.232 0.357 0.482 0.607 0.732 0.982 1.232 1.482 1.732 11 0.120 0.260 0.385 0.510 0.635 0.760 1.010 1.260 1.510 1.760 12 0.109 0.282 0.407 0.532 0.657 0.782 1.032 1.282 1.532 1.782 13 0.095 0.310 0.435 0.560 0.685 0.810 1.060 1.310 1.560 1.810 14 0.083 0.334 0.459 0.584 0.709 0.834 1.084 1.334 1.584 1.834 15 0.072 0.356 0.481 0.606 0.731 0.856 1.106 1.356 1.606 1.856 16 0.065 0.370 0.495 0.620 0.745 0.870 1.120 1.370 1.620 1.870 17 0.058 0.384 0.509 0.634 0.759 0.884 1.134 1.384 1.634 1.884 18 0.049 0.402 0.527 0.652 0.777 0.902 1.152 1.402 1.652 1.902 19 0.042 0.416 0.541 0.666 0.791 0.916 1.166 1.416 1.666 1.916 20 0.035 0.430 0.555 0.680 0.805 0.930 1.180 1.430 1.680 1.930 21 0.032 0.436 0.561 0.686 0.811 0.936 1.186 1.436 1.686 1.936 22 0.028 0.444 0.569 0.694 0.819 0.944 1.194 1.444 1.694 1.944 23 0.025 0.450 0.575 0.700 0.825 0.950 1.200 1.450 1.700 1.950 24 0.022 0.456 0.581 0.706 0.831 0.956 1.206 1.456 1.706 1.956

(15) Referring to FIG. 6, tube plug 10 may be used to plug the aperture 52 of a tubesheet 50 that is associated with a leaky or damaged tube 54 and also support tube 54 to prevent it becoming dislodged and damages adjacent tubes 54. If the tube damage is severe, or there is a crack in the tube, the tube ends may be drilled out and the tubesheet aperture 52 plugged directly with tube plug 10 without any concern that tube 54 will come loose and damage adjacent tubes. This approach avoids the need to disassembly the entire heat exchanger, as would be required to remove the tube, or to remove the surrounding tubes to avoid potential damage. The present invention is thus capable of effectively sealing a tube in high pressure situations due to the expansion of the mechanical sealing wall into the inner diameter surface of the tubesheet aperture. While tube plug 10 is designed for use in high pressure heat exchangers, the sealing system of the present invention may also be used in low pressure applications such as feedwater heaters, moisture separator reheaters, preheaters, condensers, coolers, fin-fan coolers or any other tubed heat exchanger where additional retention or sealing may be needed due to pitted or corroded inner diameter tube surface. Tube plug 10 may be made in any alloy or size for a desired application.