U.S. patent application number 11/147362 was filed with the patent office on 2006-12-14 for boiler plug.
Invention is credited to James Ivery.
Application Number | 20060277756 11/147362 |
Document ID | / |
Family ID | 37522759 |
Filed Date | 2006-12-14 |
United States Patent
Application |
20060277756 |
Kind Code |
A1 |
Ivery; James |
December 14, 2006 |
Boiler plug
Abstract
The invention relates to an apparatus for quickly and
inexpensively plugging leaks in the tubing of low pressure steam
boilers. The invention uses a cap containing a gasket channel of
the same diameter as the edge of the tube. The underside
cylindrical wall of the cap contains an aperture in common with
that of the top of the cap. A threaded rod is passed through the
cap and connected to an identical plug on the other end of the
tube. Simultaneously tightening hex nuts on the two rods seals the
tubing ends.
Inventors: |
Ivery; James; (New York,
NY) |
Correspondence
Address: |
LITMAN LAW OFFICES, LTD
PO BOX 15035
CRYSTAL CITY STATION
ARLINGTON
VA
22215
US
|
Family ID: |
37522759 |
Appl. No.: |
11/147362 |
Filed: |
June 8, 2005 |
Current U.S.
Class: |
29/890.031 ;
29/890.03 |
Current CPC
Class: |
Y10T 29/49352 20150115;
F28F 11/04 20130101; Y10T 29/4935 20150115 |
Class at
Publication: |
029/890.031 ;
029/890.03 |
International
Class: |
B21D 53/02 20060101
B21D053/02 |
Claims
1. A plug for sealing leaking boiler heat exchanger tubes
comprising: a circular steel concave cap having a top and under
side; an aperture through the top center of the cap, a major
circumference greater than the circumference of the tube; a channel
within the major circumference of the cap on the cap under side
wherein the circumference of the channel is the same as the
circumference of the tube; an elongated steel cylindrical wall
proceeding from the under side of the cap and having a minor
circumference less than the circumference of the channel, said
cylinder wall having an aperture through the length of the cylinder
continuous with the aperture at the top side of the cap; a gasket
contained in the channel; a rod through the cap and wall apertures,
said rod containing a gasket means to seal the top of the cap
aperture; and means to compress and seal the plug onto the
tube.
2. The plug according to claim 1 wherein said cap wall has a
frustum shape.
3. The plug of claim 1 wherein the diameter of the tube is three
inches.
4. The plug of claim 1 wherein the channel is a rectangular cross
section channel on the under side of the cap.
5. The plug of claim 1 wherein the channel gasket has a rectangular
cross section
6. The plug of claim 1 wherein the gasket is prepared from
asbestos
7. The plug of claim 1 where said rod is a full threaded rod longer
than the leaky tubes
8. The rod of claim 8 placed through the cap and cylinder apertures
and having a plastic gasket, steel washer and hex nut on the rod
above the cap
9. The rod of claim 9 placed through the cap and cylinder apertures
and having a plastic gasket, steel washer and hex nut on the rod
above the cap
10. A method for seating and sealing plugs to cap leaking boiler
heat exchanger tubes comprising: preparing two plugs according to
claim 1 containing threaded rods; inserting the two plugs on
opposing ends of a tube with the tube ends in contact with the two
channel gaskets; adding gasket, washer and hex nuts to the ends of
the rods; tightening the hex nuts to force the tube ends into the
channel gasket
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to low pressure water tube
steam boilers. The invention particularly relates to an apparatus
for quickly and inexpensively plugging leaks in the tubing of low
pressure steam boilers.
[0003] 2. Description of the Related Art
[0004] Low pressure tube steam boilers operating at about 12 lb
steam pressure are in demand today for applications in industrial,
commercial and public buildings. They are a vintage technology and
serve their operators very well for many years when they are
properly maintained. However, in time or under unusual
circumstances leaks develop in the flue gas-to-water steel tube
heat exchanger or conduits. These leaks, if unattended, will
quickly damage other parts of the tubular heat exchanger bundle and
can require a major overhaul or replacement of the entire heat
exchanger. In that eventuality, the boiler may be out of service
for an unacceptable length of time while the exchanger is being
replaced.
[0005] The answer to the boiler tube leak problem when it occurs is
a prompt plugging of the faulty tube with a tubing cross-sectional
plug at a position upstream of the fluid flow. That has been the
answer to tube leaks for many years, but with only partial success.
The plugs that have been used in past years have themselves, sooner
or later, leaked. Besides, some of them are expensive and require
the boiler output to be sharply turned down, sometimes for days,
before the corrective installation is complete. Some plugs have
been proposed that can be installed in the boiler on-the-fly, i.e.,
while the boiler is still hot. While limiting the boiler total down
time, these plugs, sooner or later, leak as well.
[0006] U.S. Pat. No. 5,016,674 to Kiss claims a plug for leaky
tubes of a heat exchanger. The plug consists essentially of a
frustrum shaped tapered hollow plug with the diameter of the top of
the frustrum being the widest of the plug. A plug nut is formed on
the top of the plug as part of the plug as manufactured. A threaded
rod is connected to the plug nut by passing through the hollow
plug; the exposed end of the rod receives a gasket and a rod nut.
An "O" ring is inserted inside the leaky tube around the plug. The
plug diameter at the top is less than the outside diameter of the
end of the tube. Accordingly, nothing protrudes past the outside
surface of the end of the tube. This allows close packing of the
tubes of the heat exchanger bundle. It is claimed that the "O" ring
itself, once compressed by tightening the rod nut, forms a seal
that prevents the water and hot gas from mixing.
[0007] U.S. Pat. No. 685,561 to Bettermann describes a flue plug
for plugging the ends of a boiler flue. The plugs are tapered in
shape with annular flanges dished on their under sides. A
connecting rod passes through the two plugs with a means for
tightening the plugs to push the ends of the plugs into the ends of
the flue.
[0008] None of the above inventions and patents, taken either
singly or in combination, is seen to describe the instant invention
as claimed. Thus, a boiler plug solving the aforementioned problems
of leak sealing is desired.
SUMMARY OF THE INVENTION
[0009] The boiler plug system of the invention is intended for
plugging leaks in the steel tube flue gas-to-water heat exchangers
of low pressure steam boilers which, on average, reach operating
steam pressures of about 12 pounds (lbs). Excursions above 12 lbs
may occur briefly, up to about 16 lbs, but only briefly. Lower
operating pressures as low as 8 lbs may be maintained for a period
of time to complete some ordinary maintenance of the boiler or
because of low energy demand. However, to those skilled in the art
it is well known that fixing leaks in the heat exchangers of high
pressure boilers is a substantially different matter than that of
low pressure boilers.
[0010] The preferred size of heat exchanger tubes to which the
boiler plug of the invention applies is 3 inch inside diameter
(ID). This is a commonly accepted size for boiler heat exchanger
tubing in the industry; however, larger or smaller ID tubing can be
used if the design boiler capacity substantially increases or
decreases. In this specification, the elements of the invention
will be described as applied to three inch ID steel tubing heat
exchangers with the understanding that the boiler plug of the
invention can be made smaller or larger as the particular
application may require. The boiler plug of the invention is
readily applicable to heat exchanger tubing of 2 to 4 inch ID.
[0011] The boiler heat exchanger panel consists of a closely packed
bundle of lengthy steel tubes having a diameter of about three
inches. Hot flue gasses passing from the fire box exchange heat
through the tube wall with circulating water. Due to the hot flue
gasses corrosive nature, tubing leaks frequently occur. These leaks
must be corrected relatively promptly before a leak compromises the
integrity of adjoining tubes and worsens the problem. The heat
exchanger flue tubing is cut and a boiler plug is inserted to end
the leaking.
[0012] The boiler plug of the instant invention seals the open end
of the tubing by combining two techniques: 1) placing a steel cap
over one end of the tube fitted with a precise tube end-to-cap
gasket and the same type cap and gasket on the other end of the
tube; 2) tighten down both caps by screwing down on nuts on the
ends of a threaded rod that passes through the length of the tube
and through the center of both metal caps. By this technique the
line of the rod from one cap to the other cap runs exactly down the
center of the tube circumference of the plug of the instant
invention. Consequently, the force pulling on both end gaskets is
equal around the circumference of the gaskets. This eliminates any
tendency for any side of a gasket to lift and produce a suitable
situation for a new leak to develop.
[0013] The major parts of the boiler plug of the invention are as
follows: a domed or dished steel cap having an aperture or hole at
the peaking center of the dome and a maximum circumference
marginally greater than the circumference of the end of the tube. A
circular channel is inscribed within the dished under surface of
the domed cap next to and abutting the dome cap's major
circumference edge. The circumference of the channel is the same as
the circumference of the edge of the tube. The channel is designed
to hold a gasket which exactly mates with the terminal edge of the
tube. Preferably, the gasket is made of asbestos; however,
thermally stable rubber or plastic may be used.
[0014] Attached and part of the dished under surface of the dome
cap is a frustum shaped, thick wall cylinder having a center
opening or aperture extending from top to bottom; the top major
circumference of the cylinder is attached to the under part or
dished part of the cap with the cylinder opening or aperture and
the cap aperture corresponding in true alignment.
[0015] A steel rod threaded at both ends or completely threaded
end-to-end is passed through the first cap and cylinder openings.
The rod is longer than the length of the tube which usually runs 9
to 12 feet in length. A second plug cap and assembly of the
invention is placed on the opposing open end of the tube with the
rod passed through the second plug cap. The rod may be a single,
continuous rod or it may be sections of threaded rod joined
together by one or more couplings Next, plastic gaskets are fitted
onto the ends of the rod followed by steel washers and hex nuts.
The hex nuts at both ends are completely tightened, forcing the
gaskets within each channel down onto the ends of the tube to seal
the tube from leaking.
[0016] An important element of the boiler plug of the invention is
the design of the channel and gasket that combines with the end of
the tube. The gasket is preferably a flat ring with a rectangular
cross-section as wide as the width of the channel cross-section.
The depth or height of the channel ring gasket is at least as deep
as the depth of the channel in which it is to fit or preferably
slightly somewhat greater than the depth of the channel. When the
plug is pressed against the end of the tube the tube end contacts
the gasket in place in the channel. The tube end is then pressed
onto the gasket with great force when the opposing plugs on the
threaded rod are simultaneously tightened, thereby sealing the tube
end and assuring the end of the leakage.
[0017] Another important element of the invention is the design of
the frustum shaped cylinder attached to and part of the dished
bottom of the domed cap where both apertures are in line. The
shaped cylinder helps assure that the rod, when passed through the
cap and shaped cylinder will remain centered within the length of
the tube as the rod connects with the opposite plug. Boiler tubes
are long, i.e., nine to twelve feet in length. If the rod is even
slightly misaligned at one end, it will be significantly out of
line when it reaches an opposing end. Consequently there will be an
unequal distribution of radial forces on the opposing end gasket
and a leak there will eventually develop.
[0018] These and other features of the present invention will
become readily apparent upon further review of the following
specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is an environmental angular view of the boil plug of
the invention as installed in repair of a section of boiler
tubing.
[0020] FIG. 2 is a side view cutaway of the boiler plug and rod of
the invention as installed in repair of a section of boiler
tubing
[0021] Similar reference characters denote corresponding features
consistently throughout the attached drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The present invention as displayed in FIG. 1 consists of two
virtually identical boiler plugs (10) of the invention installed on
the ends of a boiler tube (11). The installation is employed merely
to facilitate an understanding of the invention which consists of
the boiler plug (10) itself. As illustrated, the boiler plug
consists of a domed cap (12) preferably having a dished or concave
under side with an extended wall (14) attached to and part of the
domed cap underside. The extended wall (14) describes a truncated
hemisphere or frustum in shape. The major circumference of the wall
part of the domed cap underside and the minor circumference (20)
form the terminus of the extended wall (14). Through the crest or
center of the domed caps there is an aperture or opening through
the cap large enough to admit a long threaded rod (18) sufficient
to pass through the aperture of a virtually identical opposing cap
(12a). The rod may be a continuous single rod or assembled in
sections using couplings (22).
[0023] A circular channel for seating a gasket is contained in the
under side of the cap. The channel preferably has a rectangular
cross-section with a circumference larger than the maximum
circumference of wall (14) and equal to the circumference of the
tube (11). The gasket (24) is circular in shape with a rectangular
cross-section sized to fill the channel's rectangular
cross-section.
[0024] To each end of rod (18) is added a gasket (26), a washer
(28) and a hex nut (30) in that order. Upon the simultaneous
tightening of both hex nuts the ends of the tube are pressed into
the gaskets (24) to seal the tube ends while the gaskets (26) seal
the apertures in the domed cap.
[0025] Referring to FIG. 2, the figure shows the domed cap (10)
with the frustum shaped wall (14), the tube (11), rod (18), the
aperture gasket (28), washer ((26) and hex nut (30). FIG. 2 also
shows the circular gasket (24) which sits in the circular channel
(32) in contact with the edge of the tube The circumference of tube
and channel are the same.
[0026] While a circular steel domed cap is preferred as the
terminal piece in the boiler plug of the invention, other shapes
such as square and rectangular steel caps may be used. The caps may
assume any shape that can contain the same round gasket channel and
a frustum or similar shaped long wall. The long wall and the thick
cap aperture opening function together to assure that the direction
of the rod when inserted remains true to the center of the tube
circumference. This avoids biasing the seating of the opposing
channel gasket.
[0027] The gasket used to mate with the end of the tube in the
cannel gasket holder can be made from a variety of thermally stable
gasketing material including asbestos, plastic materials, soft
metal and mineral compositions and the like as known in the
art.
[0028] It is to be understood that the present invention is not
limited to the embodiments described above, but encompasses any and
all embodiments within the scope of the following claims.
* * * * *