Note: Descriptions are shown in the official language in which they were submitted.
1 326 1 28
METHOD OF APPARATUS FOR EXPANDING AND SEALING
A SL~EEVE INTO A SURROUNDING l'UBE
BACKGROUND OF INVENTION
This invention pertains to method and apparatus for
expanding and sealing a tubular sleeve into a surrounding
tube. It pertains particularly to expanding and pressure
sealing opposite ends of a close-fitting metal sleeve within
a surrounding tube, and to dual pressurizable tool devices
which are used for remotely accomplishing such sealing.
Tubes used in tubular type heat exchangers,
par~icularly tubes in air preheaters used in fossil fuel
fired steam power plants for preheating the combustion air
against hot flue gases, often develop leaks after several
years service due to metal corrosion, erosion or fatigue and
require repair or replacement. SUch tube leaks are usually
located near the tube plate, but can occur anywhere along
tbe tubes. Because replacement of tubes in such heat
exchangers is quite expens~ve, particularly for large heat
exchangers containing 10,000-50,000 tubes, and re~uires
considerable outage time for a plant, a method and special
tool devices for reliably repairinq such tubes quickly and
inexpensively in a dusty environment has been added.
Various methods and devices for remotely expand~ng
tubes into surrounding plates or tubesheets are known in the
prior art. For example, U.S. Patent 2,319,216 to Dewald
discloses a pull-type tapered tube expander for expanding
heat exchanger tubes into a tubesheet utilizing direct
contact between a tapered wedge surface and the tube inner
wall. U.S. Patent 3,470,724 to Gregg discloses a pipe end
forming machine which utilizes an external holding collet to
hold a tube end and a central tapered arbor which is pushed
through a forming collet to locally expand the tube end.
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1 326 1 28
U.S. Patent 3,829,948 to Miller et al discloses an apparatus
for expanding tubes into a tubesheet using an expandable
collet. U.S. Patent 4,182,152 to Vaill et al discloses a
grid sleeve bulqe tool used for securing internal guide
tubes to an outer sleeve and grid. Also, U.S. Patent
4,471,643 to Champoux et al discloses a tool adapted for
pulling a tapered mandrel through a sleeve to secure
together abutting workpieces. Also, U.S. Patent 4,068,372
to Kamohara et al discloses a tube expander for anchoring
tubes in a tube plate of a heat exchanger, and utilizes a
cylindrical shaped elastic medium to be expanded by axial
compression utilizing a rod inserted through the medium and
back up rings. U.S. Patent 4,387,507 to Kelly discloses
apparatus and method for radially expanding tubes for
anchoring within a tubesheet by using primary and secondary
expander rings. U.S. Patent 4,418,457 to Mueller discloses
another apparatus for expanding a tube into a tubesheet
opening and for controlling the tube expansion by axial
location of elastomer washers relative to the tubesheet.
2~ Also, U.S. Patent 4,567,631 to ~elly discloses another
apparatus for expanding tubes into tubesheets using a
plurality of elastomer expander rings loaded by axial
compression.
The known prior art has various deficiencies, and has
- 25 apparently not provided a method and self-contained tool
` devices for remotely expanding a close-fitting tubular
sleeve into a surrounding tube quickly and conveniently, so
as to provide a pressure-tight ~oint therebetween. The
prior art evidently does not disclose pressurizable tool
devices adapted for conveniently and rapidly expanding a
close-fitting metal sleeve firmly against a tube in a
tubeplate, and which can withstand repeated cycles of use
1 326 1 28
and can also be easily withdrawn from the expanded sleeve.
However, a tube repair method for inserting an elongated
close-fitting metal sleeve into a tube and radially
expanding and pressure sealing each end of the sleeve to the
tube inner wall by using improved elongated
pressure-operated tool devices has now been developed
according to the present invention. Also, special
pressurizable tools have now been developed according to the
present invention for repairing such leaking tubes by
inserting a ~ubular metal sleeve into the tube, then
inserting the tools in sequence into the sleeve and radially
expanding the sleeve to seal the sleeve pressure-tight to
the tube and to the tubeplate~
SUNNARY OF INVENTION
The present invention provides a method for expanding
opposite ends of a sleeve into a surrounding tube.
Specifically, the invention provides a method for utilizing
a first elongated tool device for remotely expanding the
forward end of a close-fitting sleeve into a surrounding
tube. The method includes the steps of inserting an
elongated close-fitting tubular sleeve into a tube so as to
extend past any opening or rupture in the tube, then
inserting the elongated extension port~on of the tool into
the sleeve and its surrounding tube, so that collet fingers
of the tool are located near the forward or inner end of the
sleeve. Next, the tool front piston is pressurized so as to
force a tapered mandrel attached to the piston forward end
through a plurality of radially expandable collet fingers,
so as to expand the fingers radially outwardly against the
inner surface of the sleeve and also expand the sleeve
132612~
firmly against tlle tube inner wall, so as to provide an
interference fit and seal therebetween. The tool front
piston is further pressurized to force the mandrel further
forward through the collet fingers to contact a reduced
diameter portion of the mandrel so as to retract the
fingers, after which the tool is withdrawn from the sealed
sleeve and tube. Finally, a rear piston of the first tool
device is pressurized to retract the mandrel rearwardly
through the collet fingers to its original position to reset
the tool ready for a new cycle of operation for the tool
device.
This invention also includes a method for expanding the
rear end of the close-fitting metal sleeve firmly into the
tube into the tubeplate or tubesheet such as in a heat
exchanger, to provide a pressure-tight interference fit
between the sleeve outer surface and the tube inner surface.
In the method, thè second tool forward end is first inserted
into the elongated metal sleeve which is positioned within
the near end of a tube in a heat exchanger. The tool
forward end including the retainer nut, elastic expander
ring unit, and housing adapter flange forward portion are
` inserted fully into the sleeve, after which the housing
front port is pressurized so as to move the piston
rearwardly and axially compress the elastic expander rings
and thereby expand them radially outwardly against the
sleeve. Such expansion also expands the rear end portion of
the metal sleeve radially outwardly firmly against the inner
surface of the tube, which is already sealed pressure-tight
within the tubesheet. The resulting ~oint made by the tool
forms a rear pressure-tight seal between the sleeve and the
damaged tube, which was previously pressure-tightly rolled
into the tubesheet opening during original manufacture of
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132612~
the heat exchanger.
Following such expansion of the elastic expander rings
and the sleeve against the tube, the housing forward port is
depressurized and the rear port is pressurized so as to move
the retainer nut forward and release the axial pressure on
the elastic rings. The tool is then withdrawn from the
expanded sleeve and tube, and is inserted into another
sleeved tube where the procedure is repeated as desired.
This invention also includes a first or inner sealing
elongated tool device adapted for remotely expanding a
sleeve into a surrounding tube to provide a pressure-tight
seal ~herebetween. The first or front sealing tool device
includes a housing and an elongated forward extension
portion attached to a front cylinder containing an axially
movable piston pressurizable through a first port in the
housing. The front cylinder is attached to an expandable
collet having a plurality of radially movable fingers
located at its forward end. A tapered mandrel attached to
~ the piston forward end has an enlarged diameter at its
- rearward end, and is arranged to be moved by the front
piston axially forward through the collet to expand the
- collet fingers radially outwardly against the inner wall of
` the sleeve into which the tool is inserted. The collet
fingers force a localized portion of the sleeve radially
outwardly until it contacts the tube, and then radially
expands both the sleeve and tube together, to radially
outwardly form a positive lock and seal joint between the
sleeve and the tube.
The mandrel also has a~ oppositely tapered reduced
diameter portion located ad~acent the rear end of the
mandrel, so that upon further mandrel forward movement the
_5_
1 326 1 28
reduced diameter rear end portion permits the collet fingers
to retract radially inwardly. Such retraction of the collet
fingers permits the tool device to be withdrawn from the
tubular sleeve and the surrounding tube to which the sleeve
has been sealed.
The tool housing extension portion also has a rear
cylinder containing an axially movable piston which is
rigidly connected to the front piston buy a central
connecting rod, and is pressurizable through a second port
in the housing. Following withdrawal of the tool device
from a tube, pressurizing the rear piston in the tool
housing will move the mandrel rearwardly through the collet
fingers to its original position, so as to reset the tool
ready for repeated usage.
The invention also includes a second or rear end
sealing pressurizable tool device for use in effectively
repairing leaking tubes in heat exchangers. The tool is
adapted for being inserted into a close-fitting sleeve
located within a tube for expanding the sleeve and tube
firmly into an opening in a tubesheet of the heat exchanger.
The tool includes a housing having a cylindrical
longitudinal bore and containing a front pressurizable port
connected to the bore, and a housing closure plate
containing a rear pressurizable port. A housing adapter
flange having a reduced diameter portion sized to fit within
the tube end is provided at.the forward end of the housing
- to facilitate locating the tool relative to the sleeve and
tubesheet. The housing cylindrical bore contains a piston
axially movable therein, which piston is attached at its
forward end to an elongated rod having an adjustable
retainer nut threadably attached thereon. An elastic
expander unit comprising at least two elastic expander rings
1 326 1 28
or washers is provided encircling the rod between the
housing flange and the adjustable retaining nut. The front
and rear expander rings preferably each have a chamfer
- provided at the front outer corner of the front ring and the
rear outer corner of the rear ring adjacent the retainer nut
and housing flange, respectively, to minimize radial outward
extrusion of each ring during repeated pressurization cycles
during use of the tool.
The expander rings are composed of an elastic elastomer
material which retains its elasticity through many high
compression and depressurization cycles during use of the
tool. Useful ring materials include polyurethane, nylon,
teflon and synthetic rubber, with polyurethane elastomer
being preferred because of its desirable high pressure
characteristics~
This invention advantageously provides a method for
effective repair for corroded or ruptured tubes and thereby
avoid expensive and time consuming rebuilding or replacement
~- of the heat exchanger. It also advantageously provides dual
elongated tools for carrying out the sealing method, the
- first ~ool being an elongated tool device which is adapted
for being inserted into a close-fitting sleeve and tube in a
heat exchanger and expanding the sleeve into the tube to
provide a leak-tight seal therebetween.
The second tool device is adapted for being inserted
into the close-fitting metal sleeve within the tube for
radially expanding the sleeve into the tubesheet to provide
a pressure-tight seal therebetween. The tool utilizes dual
elastomer expander rings which are each contoured to include
a chamfer at the outer corners of the forward and rear faces
of the seal ring unit to provide efficient radial expansion
without undesirable extrusion and achieve long useful life
- 1 3261 2~
or the rings. Such effective tube repair avoids expensive
rebuilding or replacement of heat exchanges, such as air
preheaters in fuel fired steam power plants.
BRIEF DESCRIPTION OF DRAWINGS
The invention will be described further with reference
to the following drawings, in which:
Fig. 1 shows a perspective elevation view of a portion
of heat exchanger containing a plurality of tubes, and a
pressurizable first tool device used for expanding a sleeve
into leaking tubes of the heat exchanger;
Fig.lA shows an enlarged partial sectional view of a
sleeve expanded within a tube and tubesheet of the heat
exchanger to provide a seal ~oint for the tube;
Fig. 2 shows a longitudinal cross-sectional broken view
of the elongated tool device inserted into a sleeve in a
tube, with the mandrel and collet fingers in their initial
normal unexpanded position relative to the sleeve;
Fig. ~ shows a cross-sectional view of the tool housing
taken at section 3-3' of Fig.2; as sh~wn with Fig. l;
Fig. 4 shows a partial cross-sectional view of the tool
after being pressurized, with the collet fingers being in an
expanded position within the sleeve and tube;
Fig. S shows a partial c~oss-sectional view of the tool
showing the mandrel moved to a forward position to retract
the collet fingers, and thereby permit withdrawal of the
tool from the sleeve and tube.
Fig. 6 shows a perspective elevation view of a heat
exchanger portion containing a plurality of tubes, and the
t32612~
,
second tool device used for expanding a sleeve into a tube
in a tubesheet of the heat exchanger;
Fig. 6A shows an enlarged view of a sleeve after being
expanded into a tube and tubesheet of the heat exchanger;
Fig. 7 shows a longitudinal cross-sectional view of
the tool inserted into a sleeve and tube in a tubesheet
with elastomer expander rings in a normal unexpanded
position relative to the sleeve;
Fig. 8 shows a partial longitudinal cross-sectional
lo view of the tool and tube with the expander rings and
- sleeve in an expanded position in the tube; and
Fig. 9 shows a partial sectional view of the rod and
expander ring unit of the tool.
DESCRIPTION OF INVENTION
As generally shown in Fig. 1, a vertical tubular heat
exchanger 10 has a plurality of tubes 12 which have been
expanded at their lower ends into tubesheet 13. Some of
the tubes 12 contain ruptures at 12a which are to be
~ repaired by inserting an elongated close-fitting tubular
`~ 20 sleeve 14 into each tube past the rupture 12a, and locally
~; expanding the sleeve at 15 against the inner wall of the
tube 12 so as to repair the rupture 12a by providing a
pressure-tigllt joint at each end of the sleeve 14, as is
shown in greater detail by Fig. lA. Such tube repair
joint 15 at the tube inner end is made by using a special
first elongated tool device 20 according to the present
invention. The sleeve lower end is subsequently sealed
pressure-tightly to the tube by using another tool, such
as described below.
As shown by Fig. 2, the elongated first tool device 20
includes a housing 22 which has an elongated
g
` 1 326 1 28
cylindrical-shaped front portion 23 having a reduced
diameter so a to be inserted within sleeve 14, and both are
then inserted within tube 12. An adapter 24 is threadably
attached to the forward end of extension portion 23 by
threaded joint 23a, and outer spacer tube 26 is threaded
onto the other end of adapter 24 by threads 25.
A cylinder assembly 28 is threadably attached at 27 to
the forward end of spacer tube 26. Cylinder assembly 28
includes a collet 30 which is threaded at 29a onto the
lo forward end of a cylinder 29. Collet 30 has a~ least three
radially expandable fingers 31. The forward end of each
collet finger 31 has an outwardly enlarged portion 31a
shaped so as to contact and force an adjacent portion of
sleeve 14 radially outwaxdly against tube 12, so as to
deform the sleeve firmly into the tube and thereby provide a
pressure-tight seal therebetween.
The cylinder 29 has a cylindrical bore 29b, which
contains a piston 34 having a seal ring 35 and an elongated
front portion 34a. The piston front portion is threadably
attached at 34b to an elongated mandrel 36 having an outer
- surface 36a, which is tapered rearwardly so as to have an
enlarged diameter at its rearward end. The tapered surface
36a is located ad~acent a reduced diameter portion 37 and
oppositely tapered portion 37a provided at the rear end of
the mandrel 36. A tapered nose piece 38 is threadably
attached at 39 to the forward end of the mandrel 36, to
facilitate inserting the tool assembly 20 into the sleeve 14
and tube 12, as is generally shown in Fig. 2.
An elongated inner spacer tube 40 also extends between
the adapter 24 and cylinder assembly 28 and is pressure
sealed to the adapter 24 by a seal ring 41, and is sealed to
cylinder assembly 28 by seal ring 43. The front piston 34
-10-
132612~3
is pressurized a~nd moved forward by fluid pressure being
applied at sleeve expansion port 48 in housing 22, which
port is connected to piston 34 by an annular longitudinal
passageway 47 provided in housing extension 23 and
connecting annular passageway 47a located between the inner
spacer tube ~0 and a connecting rod 46 as described below.
Located within the rear end portion of the tool housing
22 is a second cylindrical bore 42 containing an axially
movable rear piston 44 containing a seal ring 45. The rear
- 10 piston 44 is attached by a central elongated connecting rod
46 extending through the inner spacer tube 40 and is
attached to near the forward piston 34. The front side of
rear piston 44 is pressuriza~le through a longitudinal
passageway 4~, which is flow connected to piston retracting
port 50 of housing 22. The rear end of housing 22 is closed
by a plug 52 attached by threaded joint 53. Also if
desired, reduced fluid pressure can be applied at port 54 to
``the rear side of piston 44~ to augment the pressure applied
through port 48 and passageway 47 to piston 34 and force
mandrel 36 forward throuqh the collet fingers 31. The
relative locations of sleeve expansion port 48 and piston
retraction ports 50 are shown by Fig ~.
The tool device forward extension portion 23 and
cylinder assembly 28 is made to have whatever smaller
diameter is needed to be easily inserted into a snug-fitting
sleeve 14 within tube 12~ and,to have a length sufficient to
pressure seal the inner end of the sleeve 14 to the tube at
joint 15. The tool housing 22 outside diameter may be 2-3
inches, and the tool total length may be 4-a feet. The tool
is usually made about 6 feet long and its e~tension portion
have a reduced outside diameter so as to slidably fit inside
a close-fitting sleeve in a 1-2 inch diameter tube. The
-11--
1 326 1 28
taper of the mandrel 36 is made relatively small, so as to
limit the axial force necessary by piston 34 to force the
collet fingers 31 radially outwardly to expand the sleeve 14
firmly into tube 12. The radial force required at the
ringer end portion 31a is determined by the diameter, wall
thickness and yield strength of both the sleeve 14 and tube
12 and the deformation need to produce pressure-tight seal
15. The total radial force and the coefficient of friction
between the mandrel surface 36a and collet fingers 31
determines the axial force needed from piston 34 to drive
forward the mandrel 26. The amount of taper for mandrel
surface 36a may vary between about 0.050-0.065 inch diameter
per inch length of the tapered mandrel. The mandrel outer
surface 36a is usually coated with material having low
coefficient of friction, such as molybdenum disulfide to
minimize the friction between the tapered mandrel and the
~ collet fingers.
- Housing 22 has a shoulder 22a which is sized to fit
within tube 12 and against the end of sleeve 14. Also, a
spacer piece 51 is provided attached to the front end of
housing 22. During use of tool 20, the forward and of
spacer piece 51 is placed against the front face 13a of
tubesheet 13 to facilitate proper location of the enlarged
portion 31a of collet fingers 31 relative to the inner end
of sleeve 14 to produce real joint 15.
The tool device is usua~ly made of high strength alloy
steel, with the mandrel 36 being made of hardened high
car~on tool steel. The number of collet fingers 31 will
vary with the diameter of the collet and sleeve 14. For
example, for a sleeve outside diameter of 1.4 inch 6 collet
fingers have been used, and for a sleeve outside diameter of
2.9 inches 12 collet fingers have been used.
-12-
` 132612~
The method steps for using the tool devices of this
invention include first placing an elongated tubular sleeve
14 onto the forward end of tool 20, then inserting the tool
20 and sleeve 14 into a tube 12 which is to be repaired, as
5shown in Figs. 1 and 2. The first tool 20 ports 48 and S0
are connected by suitable high pressure hoses to a hydraulic
pressurizing unit (not shown). The spacer ring 51 attached
to the tool housing 22 forward end is abutted against the
face 13a of tubesheet 13~ Also, shoulder 22a of housing 22
serves to force forward the sleeve 14 and properly axially
locate the sleeve within the tube 12 for forming joint lS
therebetween.
After inserting the tool 20 within a sleeve 14 and
properly locating the sleeve 14 within the tube 12, the tool
is first pressurized at sleeve expansion port 48 to
3~00-4500 psig hydraulic pressure so as to move forward
piston 34 and tapered mandrel 36 and force collet fingers 31
radially outwardly against the sleeve 14 and tube 12, and
-then further radially expand the sleeve and tube together
outwardly and form a positive lock and seal 15 between the
sleeve and tuke, as is shown by Fig. 4.
Further forward movement of mandrel 36 through collet
fingers 31 permits the fingers to automatically retract into
the mandrel reduced diameter portion 37, as shown by Fig. 5.
The tool 20 is then withdrawn from the expanded sleeve 14
and tube 12, after which port S0 is pressurized using a
hydraulic fluid at 3500-4500 psig pressure to move the rear
piston 44 rearwardly and thereby recock the tool by
withdrawing the tapered mandrel 36 from the collet fingers
31 to the initial position as shown by Fig. 2.
As is generally shown by Fig. 6, a vertical tubular
heat exchanger 110 has a plurality of tubes 112 with their
-13-
1 326 1 2~
lower ends being expanded tightly into a lower tubesheet
113. Tube ruptures 112a in some of tubes 112 are to be
repaired by inserting a sleeve 114 into each damaged tube
and locally expanding the sleeve outer surface against the
inner wall of tube adjacent the tubesheet 113, so as to
- provide a pressure-tight seal at the lower end of the tube
112, ~s shown in greater detail by Fig. 6A. Such tube
repair is provided by inserting a special tool 120 into the
sleeve and radially expanding the sleeve 114 against the
tube 112 according to the present invention.
As shown in Fig. 7, the pressurizable tool device 120
includes a housing 122 having a cylindrical longitudinal
bore 123 and containing a pressurizable front port 124
` connected to the bore. ~ousing 122 encloses a piston 126
ax~ally movable in bore 123 and containing an outer seal
ring 125. The housing 122 rear end is closed by a head
pla~e 128, which has a forward portion 128a inserted into
bore 123 and is attached to housing 122 by a plurality of
bolts 128b and is pressure-sealed to the housing bore 123 by
outer seal ring 127. Head plate 128 is pressure-sealed
around a rear extension portion 126a of the piston 126 by
inner seal ring 129, and contains pressurizable rear port
138 flow connected to bore 123.
The piston 126 forward end is threadably attached 126b
to an elongated rod 130, which is pressure-sealed to housing
122 by O-ring 131. Rod }30 forward portion 130a has a
reduced diameter and extends through an adapter flange 132,
which is removably attached to the front face of the housing
122 by a plurality of threaded screws 133. Adapter flange
132 includes a front portion 132a having a reduced diameter
which is sized to fit within a tube 112 into which a
close-fitting sleeve 114 is to be expanded, so as to contact
-14-
1 326 1 2~
1 the rear end of the sleeve 114 and sxlally locate the ~leeve
relative to tile tube 112 and tubesheet 113. Threadably attached
to the forward end 130a of rod 130 is a retainer nut 134, which
~ may be tapered to facilitate inserting the nut and tool into a
- 5 tube and sleeve 114.
Located bet~een the adapter $1ange front portion 132a and
nut 134 is an expander unit 136 containing 2-4 contoured elastic
expsnder rings 136a, 136b, etc. The rings are made of an
~ elastic material which is capable of withstanding repeated high
`~ 10 compression loading without causing permanent deformation of the
rings. Useful elastic materials for rings 136 include
polyurethane, nylon, teflon, and synthetic rubber, with
~ polyurethane ela~tomers being preferred because of its desirable
elasticity characteristics and being able to withstand numerous
use cycles ~ithout permanent deformation. Polyurethane
elastomer has desirable characteristics of being substantially
solid under normal unpre6suri~ed conditions and behsving similar
to a hydraulic liquid ~hen highly pressurized. Polyurethane
~` elastumer also has a memory characteristic of being able to
return to substantially its original shape after a high
compressive pressure has been removed. A suitable preferred
material is polyurethane elastomer XP~-10 obtainable from Air
Products and Chemicals, Inc. (XP~-10 may be a trade-mark of Air
Products and Chemicals, Inc.~
~5 The expander ring unit 136 is preferably provided as two
annular rings or ~ashers 136a and 136b which preferably have
equal thic~ness. A chamfer 137 is provided at the forward outer
corner or edge of front ring 136a and at the rear outer corner
or edge of rear ring 136b, and serve to retard or prevent
permanent enlargemene of the ring at that location due to the
repeated a~ial loadings and high compression required for the
rings during use. The chamfer
- 132612~
137 has an angle a of 30-60 degrees with the face of the
ring, and has a radial dimension d e~ual to 15-30% of the
radius of the ring, as shown in Fig. 9.
This tool device front extension portion is made to
have a diameter slightly smaller than the sleeve for easy
insertion into the rear end of the sleeve provided within a
tube in a tubesheet. The tool extension portion length is
made sufficient to extend past the tubesheet thickness and
locate the expander rings unit 136 within the tubesheet
thickness. The tool expànder ring outside dlameter is
usually 1.0-~.0 inches, and fits snugly within a sleeve 114
` of a tube 112, and the tool forward portion length is
usually 6-12 inches depending upon the tu~esheet thickness.
The tool is suitably made of hiqh strength alloy steel.
15In the method for using the second tool device for
expanding a close-fitting metal sleeve into a tube in a
tubesheet so as to provide a pressure-tight interference fit
therebetween, the tool forward end portion is first inserted
into sleeve 114 provided in a tube 112 within a tubesheet,
20 as shown in Figs. 6 and 7. The front face of adapter flange
132 is usually placed agalnst the exposed end of tube 12 and
the front flange extension portion 132a is usually
positioned substantially in alignment with the front face of
tubesheet 113. The tool is connected by suitable hoses to a
hydraulic pressurizing unit (not shown). The housing front
port 124 is then pressurized such as to about 2000 psig
hydraulic pressure, so as to move the piston 126 rearwardly
and axially compress the elastic expander ring unit 136,
thereby radially expanding the sleeve 114 pressure-tightly
against the tube 112, as is shown by Fig. 8.
After expanding sleeve 114, the tool housing front port
124 is depressurized and the reAr port 138 is pressuriæed,
-16-
1~
1 3261 28
- which moved forward the piston 126 and the retainer nut 134
so as to release the axial loading pressure on expander ring
unit 136. The tool device 120 can now be easily withdrawn
from the tube, and inserted into another tube for further
cycles of use for sleeve expansion into tubes. It has been
found that the front expander ring 136a loses its resiliency
; first because of its loading and higher compression and
greater deformation and is replaced after about 20-30 cycles
`- of use. After another 20-30 cycles of use, both rings 136a
and 136b are replaced with new expander rings by removing
retainer nut 134.
This invention will ~e further described by the
following examples of a tool and tube configuration, which
should not be considered as limiting the scope of the
invention.
l~PL~ 1
A sleeve to tube expander first tool device according
to the invention is constructed and utilized for
preæsure-tight sealing the inner end of sleeves into tubes
of an air preheater in a power plant. The heat exchanger
and tool device have the following typical dimensions and
characteristics.
Tube inside diameter, in. 1.834
Sleeve length, in. 78
Sleeve outstde diameter, in. 1.800
Sleeve inside diameter, in. 1.634
Tool length, in. 83
Tool housing outside diameter, in. 2.5
1 326 1 23
Front piston diameter, in. 1.31
Rear piston diameter, in. 0.56
Number of collet fingers 10
Pressure on front piston, psig4000
Pressure on rear piston, psig 4000
During use~ the tool device forward extension end is
` first inserted into an elongated metal sleeve provided in a
tube of the heat exchanger, and the tool is pushed forward
against the tubesheet so that the tool collet fingers are
positioned near the front or inner end of the sleeve. The
tool front piston is pressurized by a hydraulic fluid
pressurizing unit connected to the tool, and the tapered
mandrel is forced forward to expand the collet fingers and
expand the sleeve firmly against the tube and then expand
the tube and sleeve together radially outwardly, thereby
forming a positive lock and seal between the sleeve and
tube. This pressurizing and sleeve sealing step usually
takes 10-15 seconds time. Next, the tool is withdrawn from
the sleeve and tube, after which the tool rear piston port
- 20 is pressurized by the pressurizing unit, and the mandrel
withdrawn through the collet fingers to reset the tool and
prepare it for its next cycle of use. This procedure is
repeated for each tube being repaired in the heat exchanger
using the method of the invention.
.
EXANPLE 2
,
A sleeve to tubesheet expander second tool device
according to this invention is constructed and used for
-18-
~ 326 1 23
expanding and tightly sealinq a sleeve rear end into a tube
in a tubesheet of heat exchanger. The tool device and heat
`- exchanger ha~e the following typical dimensions and
characteristics:
Tube inside diameter, in. 1.834
Sleeve outside di~meter, in. 1.800
Sleeve inside diameter, in. 1.634
Tool length, in. 8
Tool housing outside diameter, in. 4
Piston diameter, in. 3.25
Expander rings outside diameter,in.l.625
Expander ring length, in. .50
(Each of two rings)
Piston operatinq pressure, psig 2000
In use, the tool forward extension portion is first
inserted into a metal sleeve provided in a tube of the heat
exchanger, so that the expander rings are positioned in
lateral alignment with the tubesheet of the heat exchanger.
The tool front port is pressurized to 2000 psig by a
suitable hydraulic pressurizing unit connected to the tool,
which drives the piston rearwardly and compresses and
expands the expander rings and swages the metal sleeve
radially outwardly against the tube within the tube sheet.
Then the tool housing front port is depressurized and the
rear port is pressurized to 2000 psig, which moves forward
the piston to release the axial force on the expander rings
and permits the tool device to be withdrawn from the sleeve
and tube. This procedure is repeated for each tube
repaired, using the method of the invention.
Although this invention has been described broadly and
in terms of a specific embodiment, it is apparent that
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1 326 1 28
modifications and variations can be made to the tool device
:
and method of use within the scope of the invention which is
defined by the following claims.
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