Abstract:
A system and method for detecting leaks in pressurized or vacuum pipes is disclosed. A pipe clamp comprises a housing that surrounds a pipe fitting. A containment chamber within the pipe clamp prevents leaked gas from escaping into the environment. The pipe clamp is installed in series with an exhaust line to remove the leaked gas from the containment chamber. A sensor may be configured and disposed to detect a change in pressure in the containment chamber to indicate the occurrence of a leak.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to manufacturing, and more particularly to a system and method for monitoring gas pipes in a manufacturing environment. 
       BACKGROUND 
       [0002]    Semiconductor manufacturing requires a variety of process tools that utilize pressurized gas and/or vacuum to operate. Such tools include deposition tools and polishing tools, for example. In some cases, effluent adhering to pipe sidewalls gradually reduces the inside diameter of a pipe over time. This in turn makes the internal pressure higher, which can cause seal failures at pipe fittings. Often, an O-ring seal is employed in a pipe fitting which connects two pipe segments together. The increased pressure can cause O-rings to burst or leak. In a manufacturing environment with many process tools utilizing a variety of pressurized gas and vacuum sources, identifying the location of such a leak can be challenging. Furthermore, in some cases, the gases in use are highly toxic to people, warranting a need to quickly identify and locate such leaks for the safety of personnel on site. Ultrasonic leak detectors are not effective on active exhaust leaks as they can falsely identify flow in the pipe as a leak. Prior art exhaust gas detectors are large and bulky and provide only coarse information regarding the location of a leak. Therefore, it is desirable to have an improved pipe monitoring system and method for detecting and locating pipe leaks. 
       SUMMARY OF THE INVENTION 
       [0003]    In one embodiment of the present invention, a pipe clamp is provided. The pipe clamp comprises, a housing, the housing configured and disposed to surround a pipe fitting, an input port disposed in the housing, an output port disposed in the housing, and a sensor port disposed in the housing, wherein the housing and the pipe fitting form a containment chamber. 
         [0004]    In another embodiment of the present invention, a system for containing and monitoring gas pipe leakage is provided. The system comprises a first pipe clamp and a second pipe clamp. Each pipe clamp comprises a housing which is configured and disposed to surround a pipe fitting, an input port disposed in the housing, an output port disposed in the housing, and a sensor port disposed in the housing. The housing and the pipe fitting form a containment chamber. The first pipe clamp and second pipe clamp are connected in series with an exhaust line, such that the exhaust line is connected to the input port of the first pipe clamp, and the output port of the first pipe clamp is connected to the input port of the second pipe clamp. A second pipe clamp pressure sensor is configured and disposed to monitor pressure in the containment chamber of the second pipe clamp. 
         [0005]    In another embodiment of the present invention, a method for containing and monitoring gas pipe leakage is provided. The method comprises covering a pipe fitting of a monitored pipe with a pipe clamp, connecting a pressure sensor to a sensor port on the pipe clamp, monitoring pressure inside the pipe clamp via the pressure sensor, and indicating a leak in the monitored pipe in response to detecting a pressure outside of a first predetermined pressure range. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying figures (FIGs.). The figures are intended to be illustrative, not limiting. 
           [0007]    Certain elements in some of the figures may be omitted, or illustrated not-to-scale, for illustrative clarity. The cross-sectional views may be in the form of “slices”, or “near-sighted” cross-sectional views, omitting certain background lines which would otherwise be visible in a “true” cross-sectional view, for illustrative clarity. 
           [0008]      FIG. 1  is a perspective exploded view of a pipe clamp in accordance with an embodiment of the present invention. 
           [0009]      FIG. 2  is a perspective exploded view of a pipe clamp in accordance with an embodiment of the present invention illustrating a pipe fitting within the clamp. 
           [0010]      FIG. 3  is a perspective view of a pipe clamp in accordance with an embodiment of the present invention illustrating the clamp in a sealed position. 
           [0011]      FIG. 4  is a side view of a pipe clamp in accordance with an embodiment of the present invention illustrating the containment chamber of the pipe clamp. 
           [0012]      FIG. 5  is a side view of a pipe clamp in accordance with an embodiment of the present invention illustrating exhaust air flow through the pipe clamp. 
           [0013]      FIG. 6  is a side view of a pipe clamp in accordance with an embodiment of the present invention illustrating a leak in a monitored pipe. 
           [0014]      FIG. 7  is a block diagram of a system in accordance with an embodiment of the present invention. 
           [0015]      FIG. 8  is a block diagram of a system in accordance with an alternative embodiment of the present invention. 
           [0016]      FIG. 9  is a flowchart indicating process steps for a method in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  is a perspective exploded view of a pipe clamp  100  in accordance with an embodiment of the present invention. Pipe clamp  100  is comprised of a housing that is comprised of lower housing  102  and upper housing  104 . Lower housing  102  comprises input port  106 . Upper housing  104  comprises output port  108  and sensor port  114 . Upper housing  104  has semicircle interior portion  119  and lower housing  102  has corresponding semicircle interior portion  117 . Lower housing  102  has gasket  116  affixed to it along the mating edge where it meets upper housing  104 . Similarly, upper housing  104  has gasket  118  affixed to it along the mating edge where it meets lower housing  102 . In one embodiment, the gaskets  116  and  118  are comprised of rubber. The lower housing  102  and upper housing  104  may be comprised of polypropylene. In other embodiments, the lower housing  102  and upper housing  104  may be comprised of another type of plastic material. In other embodiments, the lower housing  102  and upper housing  104  may be comprised of a metal, such as stainless steal or aluminum. The upper housing  104  is fastened to lower housing  102  via fasteners  110  and  112 . The lower housing  102  has a well  130  within it. A similar well is in the upper housing (not shown). When the lower housing  102  is fastened to upper housing  104 , the wells unite to form a containment cavity and the semicircle interior portions  117  and  119  unite to surround, and fit around a pipe fitting. For simplicity in manufacturing the pipe clamp, lower housing  102  and upper housing  104  may be identical parts, although embodiments of the invention may utilize non-identical parts. 
         [0018]      FIG. 2  is a perspective exploded view of pipe clamp  100  illustrating a pipe fitting within the clamp. In this view, a first pipe segment  220  is affixed to a second pipe segment  222  via O-ring fitting  224 . Upper housing  104  and lower housing  102  surround the O-ring fitting  224  to encapsulate it within the containment cavity. 
         [0019]      FIG. 3  is a perspective view of pipe clamp  100  illustrating the clamp in a sealed position. In this view, the upper housing  104  is fastened to lower housing  102  via fasteners  110  and  112  (see  FIG. 2 ). 
         [0020]      FIG. 4  is a side view of pipe clamp  100  illustrating the containment chamber  430  of the pipe clamp. The containment chamber  430  encapsulates O-ring fitting  224 . Hence the housing (comprised of lower housing  102  and upper housing  104 ) and the fitting  224  form containment chamber  430 . Input port  106  vents into the containment chamber  430 , and the containment chamber  430  vents to output port  108  and sensor port  114 . Sensor port  114  may be capped if a sensor is not in use. 
         [0021]      FIG. 5  is a side view of pipe clamp  100  illustrating exhaust air flow through the pipe clamp. The exhaust airflow, indicated by the arrows with reference “E,” enters pipe clamp  100  via input port  106  and exits via output port  108 . A pressure sensor  532  is connected to a sensor conduit  534  which is connected to the sensor port  114 . Under steady-state conditions, where the O-ring fitting  224  is intact, a relatively constant pressure level is detected by pressure sensor  532 . In one embodiment, pressure sensor  532  is a differential pressure sensor. Pressure sensor  532  may also comprise an interface for determining the pressure, such as an analog signal, digital signal, and/or contact closure. The contact closure may be normally opened, and then close when the detected pressure is outside of a predetermined pressure range. 
         [0022]      FIG. 6  is a side view of a pipe clamp in accordance with an embodiment of the present invention illustrating a leak in a monitored pipe. In this case, the pressurized O-ring fitting  224  developed leak  636 . This causes an increased pressure reading by sensor  532  which is then used to indicate a leak in fitting  224 . The gas from leak  636  is vented out of the containment chamber  430  via output port  108 , and can be vented to a safe location (e.g. into a scrubber or other environmentally safe location). Hence, the leak is both detected, and safely mitigated. While this example described a leak that causes an increase in the pressure detected by sensor  532 , it is also possible to utilize embodiments of the present invention to detect vacuum leaks. In the case of a vacuum leak, the pressure detected by sensor  532  drops upon occurrence of a vacuum leak. The pressure drop can then be used to indicate a vacuum leak has occurred. Hence, embodiments of the present invention can identify a leak type as one of outward leak (pressure increase), and vacuum leak (pressure drop). 
         [0023]      FIG. 7  is a block diagram of a system  700  in accordance with an embodiment of the present invention. A first pipe clamp  100 A is connected in series to a second pipe clamp  100 B. The output  108 A of pipe clamp  100 A is connected to the input  106 B of pipe clamp  100 B. The pipe clamps  100 A and  100 B are in line with an exhaust line  744  that is connected to an exhaust source  740  (e.g. air pump). A sensor  532  is connected to second pipe clamp  100 B, while no sensor is connected to pipe clamp  100 A. The sensor port  114 A for pipe clamp  100 A is capped. The output of sensor  532  is connected to machine controller  742 . Machine controller  742  may be a computer comprising a non-transitory computer memory  743  that contains instructions which, when executed by processor  745  onboard machine controller  742 , activate a shutdown (or stop) sequence for process tools associated with the pipe clamp. Note, for the purposes of this disclosure, “shutdown” means putting the process tool in a stopped state, which may be a full shutdown, or other stopped, “offline” or “standby” state. The machine controller may send messages to each process tool to initiate its shutdown or stoppage. The machine controller may communicate to each process tool via a communications protocol, such as SECS/GEM, or other suitable protocol. The machine controller  742  may also indicate the leak to an operator. The indication (operator alert) may be in the form of an audible alert and/or visual alert in the production facility, such as a blinking light and buzzer. The machine controller may also send an e-mail and/or SMS (text) message to one or more addresses. 
         [0024]    In this example, two process tools ( 746 ,  748 ) are controlled by machine controller  742 . 
         [0025]    Both process tools utilize a common compressed gas line  750  (for the sake of illustrative simplicity, not all parts of compressed gas line  750  are shown). Gas line  750  has seals that are covered by pipe clamp  100 A and  100 B. Gas line  750  is referred to as a “monitored pipe” because the integrity of its fittings is monitored by pipe clamps  100 A and  100 B. The pipe clamps cover the fittings of the monitored pipe. If the fitting (or seal) covered by pipe clamp  100 A or  100 B leaks, a pressure change is detected at sensor  532 . It is then known the fitting at one or more of the pipe clamps has failed. Hence, the leak can be narrowed down to a subset of possible fittings within a production line. Note that while two pipe clamps are shown in this example, it is possible to use more than two pipe clamps. For example, eight pipe clamps may be used, where the sensor is connected to the last pipe clamp in the series, and the other seven pipe clamps have a capped sensor port. In this case, when the sensor registers a significant pressure change, it can be inferred that one of the eight fittings being monitored has failed. 
         [0026]      FIG. 8  is a block diagram of a system  800  in accordance with an alternative embodiment of the present invention. In this embodiment, each pipe clamp has a sensor. Hence, pipe clamp  100 B has sensor  532  attached to it, and pipe clamp  100 A has sensor  532 A attached to it. In this case, it may be possible to determine which seal failed by detecting which sensor ( 532 A or  532 ) measured a pressure difference first. For example, if the fitting monitored by pipe clamp  100 A fails, then sensor  532 A registers a pressure difference before pressure sensor  532 . The time delta between when sensor  532 A registers a pressure difference and when sensor  532  registers a pressure difference, depends in part, on the length of the gas line  750  between the two pipe clamps. In this way, by providing a sensor for each pipe clamp in the series, it provides for identifying which seal within the series has failed. It also provides a level of redundancy, such that if a particular sensor fails, functioning sensors on the other pipe clamps in series still register the pressure differential and can indicate a leak has occurred at a fitting along the monitored pipe. Note that while two pipe clamps are shown in this example, it is possible to use more than two pipe clamps. For example, eight pipe clamps may be used, where a sensor is connected to each of the eight pipe clamps in the series. 
         [0027]      FIG. 9  is a flowchart  900  indicating process steps for a method in accordance with an embodiment of the present invention. In this embodiment, a first pressure range and second pressure range may be established. The second pressure range is greater than, and encompasses the first pressure range. For example, the first pressure range may be −30 psi to 30 psi, and the second pressure range may be from −50 psi to 50 psi. Note that, depending on the application (e.g. pressurized gas, or vacuum) the monitored pressures may typically be either positive or negative. In process step  960 , the pressure in a pipe clamp (such as shown in  FIG. 5 ) that surrounds a monitored pipe fitting is continuously monitored. In process step  962 , a check is made to determine if a first pressure range is exceeded. If not, then monitoring of pressure continues. If yes, then the leak is classified at a first severity level, and an alert is issued in process step  964 . This may be performed by the machine controller ( 742  of  FIG. 7 ). The alert may comprise an audio and/or visual alert near the location of the leak, or sending of e-mails, text messages, or automated phone calls to convey the alert. Alternatively, a combination of techniques may be used. In process step  966  a check is made to determine if a second pressure range is exceeded. If not, then monitoring of pressure continues. If yes, then the leak is classified at a second severity level, and the machine controller ( 742  of  FIG. 7 ) activates a shutdown in process step  968  to shut down equipment that is associated with the leak. For example, if five process tools utilized a compressed nitrogen line, then all five tools may be shut down upon detection of a leak in the nitrogen line. The actions to take upon detection of a leak depend on the processes, and the type of gas. In some cases, the process tools can safely complete the current production cycle with the leak. In this case, the leak may be repaired during the next maintenance cycle. In cases where the safety of workers are at risk (e.g. the leaking gas is highly toxic), or where the product yield will significantly be impacted due to the leak (e.g. if a precursor gas is not flowing at the proper rate due to the leak), then the process tools may be shut down to address the leak immediately. Some embodiments may only issue alerts, or only activate a shutdown. Other embodiments may issue an alert, or both issue an alert and activate a shutdown. 
         [0028]    As can now be appreciated, embodiments of the present invention provide an effective way to detect and contain gas leaks that can form in pipe fittings having seals such as O-rings. Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, certain equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, circuits, etc.) the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiments of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several embodiments, such feature may be combined with one or more features of the other embodiments as may be desired and advantageous for any given or particular application.