Abstract:
A leak detector sleeve allows performing leak detection at a flanged joint. The leak detector sleeve is made of elastomeric material that allows achieving a gas-tight seal when the leak detector sleeve encircles a flanged joint. The leak detector sleeve includes a hole that communicates with a gap in the flanged joint, thereby allowing the tip of a sniffer probe to be placed in or near the hole to detect whether the flanged joint is leaking. The leak detector sleeve is made of material that will withstand the operating temperature of the flanged joint without becoming hardened or brittle. A method for detecting a leak using the leak detector sleeve allows for efficiently and conveniently detecting leaks. In addition, the sleeve may be easily used and reused without the adverse effects or intensive manual labor required in the prior art.

Description:
RELATED APPLICATION  
       [0001]     This patent application claims priority on provisional patent application 60/737,999 entitled Flange Leak Detector (FLD) filed on Nov. 17, 2005, which is incorporated herein by reference. 
     
    
     BACKGROUND  
       [0002]     1. Technical Field  
         [0003]     This disclosure pertains generally to flanged joints, and more specifically relates to leak detection at flanged joints.  
         [0004]     2. Background Art  
         [0005]     Flanged connectors have been used in a variety of different applications to produce gas-tight flanged joints. One known type of flanged joint  100  is shown in  FIG. 1 . The flanged joint  100  has two flanged connectors  110  and  120 . First connector  110  includes a pipe  112  and a flange  114 . Second connector  120  includes a pipe  122  and a flange  124  that mates with flange  114 . The two flanges  114  and  124  are typically joined using a plurality of bolts, two of which are shown in  FIG. 1  as  132  and  134 . Bolts  132  and  134  pass through aligned holes in flanges  114  and  124 , and corresponding nuts  142  and  144  are used to tighten the bolts and thus mate flanges  114  and  124  in a gas-tight manner to form a flanged joint. The coupling between flanges  114  and  124  is not shown because the manner in which the flanges are coupled to form a flanged joint is well-known in the art.  
         [0006]     Flanged connectors are often used to distribute various liquids and gasses in pipelines and equipment that use the liquids and gasses. One example of an apparatus that uses flanged connectors is gas turbines that generate electricity from natural gas. In a typical gas turbine, there are a large number of burners that must each be supplied with natural gas. As a result, a gas turbine may have a large number of flanged connectors that form flanged joints.  
         [0007]     Gas turbines require periodic maintenance. Maintaining a gas turbine often requires disassembling the turbine at the flanged connectors in order to clean or replace fuel screens, repair of breakdowns, periodic scheduled inspections, periodic scheduled maintenance, etc. When the flanged connectors are reassembled into a flanged joint, a check is typically made to make sure the flanged joint does not leak gas. Referring to  FIG. 2 , a method  200  represents a known way to perform gas leak detection after reassembling a flanged joint. Masking tape is wrapped around the flanges of a flange joint to enclosed the gap between flanges (step  210 ). A hole is then made in the masking tape (step  220 ), typically by pressing the point of a pen or pencil through the masking tape. The tip of a sniffer probe of a gas detector is then placed in or near the hole (step  230 ). If the flanged joint is leaking gas, the masking tape will contain the gas in the gap between the flanges so the sniffer probe can detect the gas.  
         [0008]     The prior art method  200  for detecting gas leaks at a flanged joint is effective, but leads to problems later on when the flanged joint needs to be disassembled again, as shown in method  300  in  FIG. 3 . Before the flanged joint is disassembled, the masking tape must manually be removed from the flanges (step  310 ). The process of removing the masking tape is very time-consuming and tedious. Because the flanges are very hot when the turbine is operating, the masking tape becomes very brittle and the adhesive on the tape becomes baked-on. As a result, a service person for the gas turbine may spend 30 minutes or more removing the masking tape on each flanged joint. While removing the masking tape, small brittle pieces of the tape may fall between the flanges. Because the gas turbine is typically exhausted through large stacks, airflow to the stacks creates a slight vacuum that sucks any pieces of masking tape into the turbine. The service person disassembles the flanged joint (step  320 ). In the processing of disassembling the flange joint, any small piece of masking tape between the flanges may get sucked into the gas turbine. If the service person notices a piece of masking tape getting sucked into the turbine, further disassembly typically is required to locate and retrieve the piece of masking tape. If the service person does not notice a piece of masking tape getting sucked into the turbine, the service person may completely reassemble the turbine, then test it only to find that a burner is not operating correctly due to a blockage caused by the piece of masking tape. As a result, the service person will have to disassemble the gas turbine again to locate the blockage and remove it, greatly increasing the time to service the gas turbine. Without a way to perform gas leak detection of flanged joints in a way that does not cause the problems associated with the masking tape used in the prior art, service technicians of flanged joints will continue to spend excessive time dealing with the problems that arise from using the masking tape.  
       BRIEF SUMMARY  
       [0009]     A leak detector sleeve allows performing leak detection at a flanged joint. The leak detector sleeve is made of elastomeric material that allows achieving a gas-tight seal when the leak detector sleeve encircles a flanged joint. The leak detector sleeve includes a hole that communicates with a gap in the flanged joint, thereby allowing the tip of a sniffer probe to be placed in or near the hole to detect whether the flanged joint is leaking. The leak detector sleeve is made of material that will withstand the operating temperature of the flanged joint without becoming hardened or brittle. A method for detecting a leak using the leak detector sleeve allows for efficiently and conveniently detecting leaks. In addition, the sleeve may be easily used and reused without the adverse effects or intensive manual labor required in the prior art.  
         [0010]     The foregoing and other features and advantages will be apparent from the following more particular description, as illustrated in the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)  
       [0011]     The disclosure will be described in conjunction with the appended drawings, where like designations denote like elements, and:  
         [0012]      FIG. 1  is a side view of a prior art flanged joint;  
         [0013]      FIG. 2  is a flow diagram of a prior art method for performing leak detection of a flanged joint;  
         [0014]      FIG. 3  is a flow diagram of a prior art method for disassembling a flanged joint;  
         [0015]      FIG. 4  is a perspective view of a circular leak detector sleeve;  
         [0016]      FIG. 5  is a perspective view of a linear leak detector sleeve;  
         [0017]      FIG. 6  is a side view of the linear leak detector sleeve in  FIG. 5  when overlapped and attached to itself;  
         [0018]      FIG. 7  is an enlarged view of the overlap region  610  of the linear leak detector sleeve in  FIG. 6  showing a hook-and-loop fastener;  
         [0019]      FIG. 8  is an enlarged view of the overlap region  610  of the linear leak detector sleeve in  FIG. 6  showing a snap fastener;  
         [0020]      FIG. 9  is an enlarged view of the overlap region  610  of the linear leak detector sleeve in  FIG. 6  showing an adhesive fastener;  
         [0021]      FIG. 10  is an enlarged view of the overlap region  610  of the linear leak detector sleeve in  FIG. 6  showing a zipper-type fastener;  
         [0022]      FIG. 11  is an enlarged view of the overlap region  610  of the linear leak detector sleeve in  FIG. 6  showing a first buckle fastener;  
         [0023]      FIG. 12  is an enlarged top view of the overlap region  610  of the linear leak detector sleeve in  FIG. 6  showing a second buckle fastener;  
         [0024]      FIG. 13  is an enlarged side view of the second buckle fastener shown in  FIG. 12 ;  
         [0025]      FIG. 14  is an enlarged side view of a connector that may be placed in the hole  420  of the sleeve  400  in  FIG. 4  or the sleeve  500  in  FIG. 5 ;  
         [0026]      FIG. 15  is an enlarged side view of the connector in  FIG. 14  coupled to a tube;  
         [0027]      FIG. 16  is a cross-sectional view of an alternative configuration for the leak detector sleeve that includes outer lips that help to locate the flanged sleeve in the correct position;  
         [0028]      FIG. 17  is a cross-sectional view of an alternative configuration for the leak detector sleeve that includes an inner rib that helps to locate the flanged sleeve in the correct position;  
         [0029]      FIG. 18  is a cross-sectional view of an alternative configuration for the leak detector sleeve that includes multiple inner ribs that helps to locate the flanged sleeve in the correct position;  
         [0030]      FIG. 19  is a front view showing an expander tool for expanding the leak detector sleeve;  
         [0031]      FIG. 20  is a side view of the expander tool in  FIG. 19  taken along the line  20 - 20 ;  
         [0032]      FIG. 21  is a cross-sectional view of a portion of the expander tool in  FIG. 19  taken along the line  21 - 21 ;  
         [0033]      FIG. 22  is a flow diagram of a method for performing leak detection of a flanged joint;  
         [0034]      FIG. 23  is a flow diagram of a method for disassembling a flanged joint;  
         [0035]      FIG. 24  is a flow diagram of a method for performing leak detection of a flanged joint using a leak detector sleeve that includes a tube coupled to the hole of the leak detector sleeve;  
         [0036]      FIG. 25  is a flow diagram of a method for visually inspecting flanged joints for leaks using the leak detector sleeve;  
         [0037]      FIG. 26  is a top view of a visual leak indicator that shows color when a leak in the flanged joint is present;  
         [0038]      FIG. 27  is a side view of the visual leak indicator of  FIG. 26 ;  
         [0039]      FIG. 28  is a top view of a visual leak indicator that lights up when a leak in the flanged joint is detected;  
         [0040]      FIG. 29  is a side view of the visual leak indicator of  FIG. 28 ;  
         [0041]      FIG. 30  is a top view of a visual leak indicator that pops up when a leak in the flanged joint is detected;  
         [0042]      FIG. 31  is a side view of the visual leak indicator of  FIG. 30 ;  
         [0043]      FIG. 32  is a side view of a visual leak indicator that rolls out like a party favor when a leak in the flanged joint is detected; and  
         [0044]      FIG. 33  is the side view of the visual leak indicator in  FIG. 32  that is rolled out to indicate a leak in the flanged joint. 
     
    
     DETAILED DESCRIPTION  
       [0045]     A prior art flanged joint  100  is shown in  FIG. 1 , along with prior art methods  200  and  300  in  FIGS. 2 and 3 , respectively. The prior art is discussed in detail in the Background section above. The leak detector sleeve disclosed herein provides significant advantages when compared with the prior art by providing a sleeve that can withstand the operating temperatures of the flanged joint and that can be easily installed, removed when the flanged joint needs to be disassembled, and reinstalled after the flanged joint is reassembled.  
         [0046]     Referring to  FIG. 4 , a first configuration for the leak detector sleeve  400  includes a circular band  410  that includes a small hole  420 . Band  410  preferably has a width sufficient to span gap  150  between flanges of a flanged joint, as shown in  FIG. 1 , and most preferably has a width that spans to the outer edges  152  of the flanges of a flanged joint, also shown in  FIG. 1 . Hole  420  is located an any location on the band  410  that allows the hole  420  to communicate with the gap between flanges of a flanged joint, as shown at  150  in  FIG. 1 . In the most preferred configuration, the hole  420  is located at substantially the center of the width of the band  410 . Leak detector sleeve  400  is preferably fabricated of an elastomeric material such as silicone rubber that provides sufficient elasticity so that the leak detector sleeve  400  may be slightly expanded and placed on a flanged joint such that the interface between the leak detector sleeve  400  and the flanges of the flanged joint achieve a gas-tight seal when the sleeve  400  contracts around the flanges. The operating temperature of a flanged joint may be as high as 200 degrees Celsius or more. Silicone rubber is especially well-suited because of its elasticity and tolerance to relatively high heat, including at temperatures in excess of 200 degrees Celsius. While silicone rubber is one suitable elastomeric material that can be used, any suitable elastomeric material may be used, including (without limitation) the following rubbers: buna-N, butyl, ethylene-propylene-diene-methylene (EPDM), epichlorohydrin (ECH), gum rubber, hypalon, latex, neoprene, polyurethane, styrene-butadiene, santoprene, sorbothane, vinyl and viton.  
         [0047]     Referring to  FIG. 5 , a second configuration for the leak detector sleeve  500  includes a linear band  510  with a hole  420 . Hole  420  is located an any location on the band  510  that allows the hole to communicate with the gap between flanges of a flanged joint, as shown at  150  in  FIG. 1 . In the most preferred configuration, the hole  420  is located at substantially the center of the width of the band  510 . Linear band  510  is preferably wrapped around the flanges of a flanged joint and attached to itself using a fastener  520  in an overlap region  610  shown in  FIG. 6 . The overlap region  610  shown in  FIG. 6  is a relatively small portion of the length of the band  510 . Note, however, that the band  510  may have sufficient length to allow wrapping the band  510  around the flanges to achieve any suitable length of overlap region, including multiple wraps of band  510 .  
         [0048]     Any suitable fastener  520  may be used to attach the band  510  to itself in the overlap region  610 . Suitable fasteners include one or more hook-and-loop fasteners, one or more snaps, one or more adhesive regions on band  510  that allows band  510  to be attached to itself, one or more zippers, one or more buckles, or any other type of fastener, whether currently known or developed in the future, that is capable of attaching one portion of band  510  to another portion of band  510  when band  510  is wrapped around flanges of a flanged joint. Some examples of suitable fasteners are shown in  FIGS. 7-13 .  FIG. 7  shows a hook-and-loop type fastener  700  that includes a hook portion  720  on a first portion  722  that attaches to a loop portion  710  on a second portion  712 .  FIG. 8  shows a snap fastener  800  with a male portion  810  and a female portion  820  that allows the male portion  810  to be snapped into the female portion  820 .  FIG. 9  shows an adhesive region  910  on the band that allows the band  510  to stick to itself. Adhesive region  910  most preferably includes a low-strength adhesive that allows the band  510  to be reused a number of time, but may optionally include high-strength adhesive that creates a permanent bond.  FIG. 10  shows a zipper-type fastener with a first portion  1010  that may be zipped to second portion  1020 . The fastener shown in  FIG. 10  is also representative of an alligator transmission belt lacing that is commonly used to join two sections of a conveyer belt together.  FIG. 11  shows a first buckle-type fastener.  FIGS. 12 and 13  show a second buckle-type fastener that includes a stud  1210  that includes a head portion  1220  and a reduced-diameter post  1230 , with a keyhole-shaped opening  1240  that includes a circular portion  1250  that is larger than the head portion  1220  of the stud, and a slot portion  1260  that is larger than the reduced-diameter post  1230  but smaller than the head portion  1220  of the stud. This configuration allows the head portion  1220  to be placed within the circular portion  1250 , and the elastomeric nature of the band  510  will then cause the reduced diameter portion  1230  to slide along the slot  1260 , thereby fastening the band to itself.  
         [0049]     Referring to  FIG. 14 , a connector  1400  may be used to attach a tube to the hole  420  in the leak detector sleeve. The connector  1400  preferably has a circular cross-section, and includes first and second members  1410  and  1430  that have a diameter larger than the hole, and a reduced diameter portion  1420  between first and second members  1410  and  1430  that has a diameter larger than the hole  420 . This configuration provides a gas-tight connection between the connector and the hole  420  when the hole  420  is placed over the first member  1410  such that the hole contracts against the reduced diameter portion  1420 . Connector  1400  also includes a body portion  1440  for attaching to an optional tube.  FIG. 15  shows connector  1400  attached to the first end of a tube  1500 . The second end of the tube  1500  may be connected to any suitable gas detector or liquid detector. When the leak detector sleeve  400  or  500  is used with the connector  1400  and tube  1500  shown in  FIG. 15 , the sleeve may be used to detect leaks of any gas or liquid at the flanged joint. For example, the second end of tube  1500  may be connected to a detector that provides an audible alarm, or that provides electronic detection of the leak draft 2 and notification to shut down a process that is causing gas or liquid to flow through the flanged joint.  
         [0050]     The leak detector sleeve may include optional features that aid in its installation and use, as shown in  FIGS. 16-18 .  FIG. 16  shows band  410  that includes a first lip  1610  on a first outer edge and a second lip  1620  on a second outer edge of the leak detector sleeve. These lips  1610  and  1620  allow the sleeve to be properly installed on a flanged joint, the upper part of which is shown in phantom in  FIGS. 16-18 . Note that the leak detector sleeve may include a lip on one or both outer edges. Referring to  FIG. 17 , the leak detector sleeve  400  may also optionally include a rib  1710  parallel to the outer edges of band  410  that simplifies the aligning of band  410  on the flanges of a flanged joint. Referring to  FIG. 18 , the leak detector sleeve  400  may optionally include a plurality of ribs  1810  and  1820  that align with edges of the flanges of a flanged joint that simplify the aligning of band  410  on the flanges of a flanged joint. While the circular leak detector sleeve  400  is referenced in  FIGS. 16-18 , this is shown by way of example, and the optional features in  FIGS. 16-18  could also be incorporated into linear leak detector sleeve  500  as well.  
         [0051]     A tool may be used to install the circular leak detector sleeve  400  shown in  FIG. 4 . Referring to  FIG. 19 , a tool  1900  includes handles  1910  and jaws  1920  that operate similar to conventional pliers. The jaws  1920  are preferably semi-circular in shape so they form a circle having an inner diameter that is approximately the same as the outer diameter of flanges on a flanged joint when the handles are squeezed together such that the jaws  1920  contact each other. By spreading the handles apart, the circular leak detector sleeve  400  may be expanded so it may be easily placed on the flanges of a flanged joint. Note that the jaws  1920  of the tool  1900  spread apart a sufficient distance to allow a pipe to pass through the gap between the jaws, thereby allowing the jaws  1920  to encircle a flanged joint when it is coupled to a pipe.  
         [0052]     A side view of tool  1900  is shown in  FIG. 20 , and represents the view of the tool in  FIG. 19  taken along the line  20 - 20 . Note that jaws  1920  have a relatively wide, tapered shape that allows a circular leak detector sleeve  400  to be expanded in a non-uniform manner. The jaws  1920  of the tool preferably have a tapered cross-section as shown in  FIG. 21 , with a flat portion  2120  being against the flanges and the tapered portion  2110  being against the leak detector sleeve as the leak detector sleeve is being installed. The tapered edges allow the circular leak detector sleeve to more easily slide off the tool onto the flanged joint.  
         [0053]     With the leak detector sleeves shown in  FIGS. 4 and 5 , the method for detecting leaks at a flanged joint becomes much easier compared to the prior art method that uses masking tape discussed in the Background section above. Referring to  FIG. 22 , a method  2200  for detecting a leak at a flanged joint begins by placing a leak detector sleeve over the flanges of a flanged joint (step  2210 ). A sniffer probe is then placed in or near the hole in the leak detector sleeve (step  220 ). Any gas that leaks at the flanged joint is trapped by the leak detector sleeve, thereby allowing the sniffer probe to detect a gas leak at the flanged joint.  
         [0054]     Referring to  FIG. 23 , a method  2300  for disassembling a flanged joint begins by removing a leak detector sleeve from the flanges of the flanged joint (step  2310 ). The flanged joint is then disassembled (step  320 ). Note that removing the elastomeric sleeve in step  2310  takes only a few seconds, instead of requiring several minutes to scrape the old masking tape off the flanges. The sleeve is thus reusable and provides significant labor savings compared to known methods of leak detection at flanged joints.  
         [0055]     A leak detector sleeve may include a connector with a tube as shown in  FIG. 15  installed in hole  420 . With this configuration, it is possible to detect and report leaks remotely. Referring to  FIG. 24 , a method  2400  begins by placing a leak detector sleeve that includes a tube at its hole over the flanges of a flanged joint (step  2410 ). If a substance leaks at the flanged joint, the substance may be detected at the end of the tube (step  2420 ). Note that the location of the tube on the flanged joint may depend on the gas or liquid being detected. If a gas that is lighter than air is being detected, the tube could be placed on the top of the flanged joint. If a gas that is heavier than air or a liquid is being detected, the tube could be placed at the bottom of the flanged joint. The tube allows the leak to be detected and reported via an alarm or via electronic notification that can be used to shut down a process that causes the gas or liquid to flow through the flanged joint.  
         [0056]     In the most preferred use of the circular leak detector sleeve  400 , the sleeve  400  may be installed on a flanged joint during the initial installation of the flanged joint. Whenever disassembly of the flanged joint is required, the sleeve  400  may be easily slid off the flanges, and the flanged joint may be disassembled. Once the flanged joint is reassembled, the sleeve may be easily reinstalled on the flanged joint to detect whether a leak exists at the flanged joint. In this manner, it may be possible to use a single sleeve for the entire useful life of the flanged joint. The result is significant labor savings when servicing flanged joints. Note that leak detector sleeve  400  may be any suitable size to accommodate any size of flanged joints.  
         [0057]     The linear leak detector sleeve  500  may include a single fastener that makes leak detector sleeve  500  suitable for a particular size of flanged connection, or may include multiple fasteners that makes leak detector sleeve  500  suitable for use with flanged connections of various sizes. For example, the leak detector sleeve  500  could include a single hook portion of a hook-and-loop fastener, and several spaced-apart loop portions that allow the leak detector sleeve  500  to be adjusted to a wide range of flange sizes. The linear leak detector sleeve  500  is well-suited to performing leak detection on pipelines and other flanged connections where disassembly of the connection is not normally performed. In both the circular leak detector sleeve  400  and the linear leak detector sleeve  500 , there is no adhesive on the interior portion that contacts the flanges of a flanged joint, thereby preventing the problems associated with cleaning adhesive off of the flanges when the leak detector sleeve is removed.  
         [0058]     Visual leak indicators may also be used in connection with the leak detector sleeves  400  and  500  described above. Referring to  FIG. 25 , a method  2500  uses a visual leak indicator with a leak detector sleeve to provide a visual indication of a leak at a flanged joint. First, a leak detector sleeve that includes a visual leak indicator is placed over the flanges of a flanged joint (step  2510 ). The visual leak indicator is placed in the hole  420  in the leak detector sleeve, and is preferably positioned so it may be visually observed by an inspector. The inspector then visually inspects the visual leak indicator to determine if a leak exists in the flanged joint (step  2520 ). The visual leak indicator in combination with a leak detector sleeve provides a simple and effective way to visually determine whether a leak exists at a flanged joint.  
         [0059]     There are many possible variations for a visual leak indicator, and the claims herein expressly extend to any suitable visual leak indicator, whether currently known or developed in the future. Possible configurations for visual leak indicator are shown in  FIGS. 26-33 . The visual leak indicators shown in  FIGS. 26-33  all include a connector  1400  similar to that shown in  FIGS. 14 and 15  that allows simply coupling the visual leak indicators to the hole  420  in the leak detector sleeves  400  and  500 . Visual leak indicator  2600  in  FIGS. 26 and 27  includes an enclosure  2620  that encloses an indicator sheet  2610  that changes color when it comes in contact with the gas or liquid that passes through the flanged joint. A transparent window above the indicator sheet allows an inspector to visually determine whether a leak at the flanged joint exists by checking the color of the indicator sheet  2610 .  
         [0060]     Referring to  FIGS. 28 and 29 , a visual leak indicator  2800  includes an enclosure  2820  with a light  2810  that is turned on to indicate a leak. Enclosure  2820  preferably houses a small battery and electronics powered by the battery that detect a leak and illuminate the light  2810  when a leak is detected. Light  2810  can be any suitable color. Referring to  FIGS. 30 and 31 , a visual leak indicator  3000  includes a cylindrical enclosure  3020  with a cylindrical indicator  3010  that pops up to indicate a leak. This can be thought of as being similar to a pop-up timer on a turkey that indicates a turkey is done. When a leak is detected, the indicator  3010  pops out of the housing  3020 . Referring to  FIGS. 32 and 33 , visual leak indicator  3200  includes a rigid portion  3210  and a flexible portion  3220  that is rolled up when there is no leak, and that rolls out as shown in  FIG. 33  when the pressure of a leak in the flanged joint causes the flexible portion  3220  to unroll. Visual leak indicator  3200  can be thought of as being similar to a child&#39;s party favor that unrolls when the child blows in it.  
         [0061]     Note that the various visual leak indicators shown in  FIGS. 26-33  can not only indicate the presence of a leak, but can also provide an indication of the severity of the leak. For example, the indicator sheet  2610  in  FIGS. 26 and 27  could turn a light color for a slight leak, and a much darker hue of the same color or even a different color for a more significant leak. The light  2810  in  FIGS. 28 and 29  could be dim for a slight leak, and bright for a more significant leak. In the alternative, the light  2810  in  FIGS. 28 and 29  could flash slowly for a slight leak, and flash quickly for a more significant leak. The cylindrical indicator  3010  in  FIGS. 30 and 31  could function similar to a tire gauge, popping up slightly to indicate a slight leak, and popping up higher to indicate a more significant leak, with the height being proportional to the pressure between the flanges of the flanged joint. The visual leak indicator  3200  in  FIGS. 32 and 33  would unroll slightly for a slight leak, and unroll most or all of the way for a more significant leak. Note that holes could be placed at the far tip of the flexible portion  3220  so that the flexible portion  3220  does not rupture when a significant leak occurs.  
         [0062]     Note that the visual leak indicator may be used in conjunction with a tube as shown in  FIG. 15  so the visual leak indicator may be placed at a remote location with respect to the flanged joint. This flexibility allows placing visual leak indicators at a location that is more convenient for visual inspection. For example, in a large gas turbine that generates electricity, the flanged joints on the gas supply lines could include tubes that all run to a common panel with visual leak indicators. This configuration allows an inspector to visually inspect the visual leak indicators for all the flanged joints at a single location, thereby simplifying the inspector&#39;s job.  
         [0063]     The ability to easily provide visual leak indicators in combination with the leak detector sleeve provides a simple and cost-effective way to detect leaks in a variety of different environments. For example, leak detector sleeves with visual leak indicators could be placed at each flanged joint along the length of a long pipeline. An inspector can easily determine whether any of the flanged joints are leaking by visually inspecting the visual leak indicators at each joint. A complex installation, such as a power plant, could use leak detectors sleeves with visual leak indicators on each flanged joint, allowing an inspector to easily determine from a visual inspection whether any flanged joints are leaking.  
         [0064]     One skilled in the art will appreciate that many variations are possible within the scope of the claims. Thus, while the disclosure is particularly shown and described above, it will be understood by those skilled in the art that these and other changes in form and details may be made therein without departing from the spirit and scope of the claims.