Abstract:
An oil leak detection device and system is installed in a double carcass hose in communication with a collection space between inner and outer carcass layers of the hose. The oil leak detection device communicates information relating to the presence or absence of fluid within the collection space to a remote location. The leak detection device is positioned within a chamber within the hose nipple. The chamber communicates with the collection space and collects oil leaking through the inner carcass into the collection space between the inner and outer carcass layers. The oil leak detection device is preferably an electro-optic sensor having optical detection means for detecting the presence and absence of fluid in the collection chamber, and communication means for transmitting information regarding the detected fluid status to a remote display unit. The display unit may include visual and/or audible indicia identifying the status and location of a plurality of sensors and thereby identify the location of a specific leak.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates generally to offshore pumping stations and, more specifically, to hose leak detection systems deployed within the context of such pumping stations.  
         BACKGROUND OF THE INVENTION  
         [0002]    In offshore pumping operations, there is a systematic risk of oil leakage to the sea from damage to single carcass submarine or floating oil suction and discharge hoses. As used herein, a “single carcass hose” is a hose construction comprising only one carcass layer. Leakage from a single carcass hose may from a precipitous hose failure or a failure that materializes over time. Hose failure may result from overpressure of the system, a puncture from outside, sudden tensile break of the hose body, defects in the manufacture, construction or design of the hose, etc. In a single carcass hose construction, hose failure results in immediate oil leakage to the environment surrounding the hose. Such leakage is highly undesirable for obvious environmental and economic reasons.  
           [0003]    Because of the risk of failure inherent in single carcass hose construction, a “double carcass” hose construction has been proposed and developed by those in the industry. A double carcass hose construction utilizes an outer hose carcass confining an inner hose carcass as an added safeguard. The outer hose functions to hold any oil or fluid that leaks through the inner hose carcass for a certain designed period of time. In a typical double carcass construction, a hose includes a main pressure cord or carcass layer as a primary confinement and an outer, or auxiliary, pressure cord layer formed so as to sheathe the inner carcass. A buffering space is defined between the carcass layers to retain fluid that leaks from the inner carcass. In use, it is common to connect hoses end-to-end to form a hose line for transporting oil or other fluid under pressure. U.S. Pat. No. 5,244,016 discloses a hose representative of the state of the art double carcass construction.  
           [0004]    A double carcass hose is generally produced and utilized in two different types: submarine or floating configurations, depending on the type of application and offshore oil pumping system. Submarine applications require that a hose extend in submerged fashion between two points whereas a floating application requires that the hose extend across the water surface. In either application, leakage from the hose results in the aforementioned undesirable consequences.  
           [0005]    In order to minimize the damage resulting from an undetected leak, various leak detection systems have been proposed and adopted. Such systems generally are based in theory on observation or mechanical manipulation of a hose to ascertain the existence and location of a leak. Mechanical manipulation may take the form of twisting a hose along its axis; scoring of the outer hose carcass; or a pin located at the hose nipple that indicates by its position whether a leak is present. Mechanical systems, however, require visual inspection by professional scuba divers. Such visual inspections can only be conducted, as a practical matter, during daylight because visibility is extremely limited during night hours. Limiting pumping operation to daylight hours, as is commonly done in pumping operations, results in production inefficiency. Inclement weather conditions, moreover, may periodically make the utilization of divers to inspect hose lines impossibly dangerous. The delays associated with waiting for weather to clear further adds operational cost. In addition, the labor cost associated with deployment of professional divers to inspect hose lines is considerable. Accordingly, mechanical systems requiring visual inspection, while better than no leak detection system, represent a less than ideal solution to the industry&#39;s need for a reliable and cost effective hose leak detection system.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention obviates the deficiencies with state of the art hose leak detection by providing a system that remotely senses the existence and location of a leak without the need for a visual inspection. An oil leak detection device and system is installed in the hose in communication with a collection space between inner and outer carcass layers of the hose. The oil leak detection device communicates information relating to the presence or absence of fluid within the collection space to a remote location.  
           [0007]    According to a further embodiment of the invention, the leak detection device is positioned within a chamber that is incorporated within the hose nipple. The chamber communicates with the collection space and collects oil leaking through the inner carcass into the collection space between the inner and outer carcass layers.  
           [0008]    According to a further embodiment of the invention, the oil leak detection device is an electronic sensor having detection means for detecting the presence and absence of fluid in the collection chamber, and communication means for transmitting information regarding the fluid status within the collection chamber to a remote display unit. The display may include visual indicia identifying the status and location of a plurality of sensor devices in a hose line system.  
           [0009]    According to another embodiment of the invention the detection means may utilize optical means for detecting the presence and absence of fluid in the collection chamber.  
           [0010]    According to a further embodiment of the invention, detection means may be located at each of two opposite ends of a hose line segment in a hose system comprising hose line segments coupled end-to-end.  
           [0011]    Yet a further aspect of the invention is to provide a method for leak detection in a double carcass hose line system comprising the steps: positioning at least one detection means in communication with a fluid collection space between the inner and outer carcass of a hose line segment, the detection means including means for detecting the presence and absence of fluid in the collection space; communicating information regarding the fluid status of the collection space to a remote location; and indicating at the remote location the fluid status within the collection space.  
           [0012]    These and other embodiments and aspects of the invention, which will be apparent to those skilled in the art, are achieved by a preferred embodiment that is described in detail below and illustrated in the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The invention will be described by way of example and with reference to the accompanying drawings in which:  
         [0014]    [0014]FIG. 1 is a schematic representation of one application of the subject invention in an offshore oil pumping station.  
         [0015]    [0015]FIG. 2 is a right front perspective view of a fluid detection sensor pursuant to the invention.  
         [0016]    [0016]FIG. 3 is a side elevation view of the fluid detection sensor with portions in section for the purpose of illustration.  
         [0017]    [0017]FIG. 4 is a plan view of a representative display unit configured pursuant to the invention.  
         [0018]    [0018]FIG. 5 is a side elevation view partially in section of a hose nipple having a fluid detection sensor incorporated therein pursuant to the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Referring initially to FIG. 1, an offshore oil drilling application is depicted by way of example incorporating a double carcass hose with built-in electronic remote oil leak detection system  10  configured pursuant to the subject invention. The offshore oil drilling station of FIG. 1 is but one of many applications for the invention and the invention is not intended to be limited thereto. Any application in which a double carcass hose is utilized for the transportation of a fluid can utilize the subject leak detection system and the teachings herein set forth.  
         [0020]    The representative field application of FIG. 1 is schematically represented by a tanker or platform  12  on which a control unit or panel  14  (FIG. 4) is located. Extending from the tanker  12  is a network of floating hose lines  16  comprising end to end connected hose segments  18  joined together by a coupling  20 . The floating lines  16  extend to a buoy  22  and connect thereto by a coupling  24 . Submarine hose lines  26  depend from buoy  22  and comprise hose segments  28  connected end to end by couplings  30 . Submarine hose lines  26  terminate at a pump station  32 . Oil is pumped from station  32  upward through hose lines  26  to the floating lines  16  and therein to the tanker  12 . Pursuant to the invention, as explained in detail below, leak detection sensors  34  are disposed within the hose lines  16  and  26  to detect fluid leakage and prevent the fluid from escaping into the sea. Preferably, although not necessarily, each hose segment is provided with two sensors  34 . More or fewer sensors per hose line or hose line segment may be deployed if desired.  
         [0021]    A representative electro-optic embodiment of a fluid detection sensor  34  is shown in FIGS. 2 and 3. While the embodiment illustrated is a preferred form for the sensor  34 , the subject invention is not intended to be so limited. Other forms of sensors and associated circuitry for detecting the presence of fluid and generating a warning signal in the event of leak detection, that will be apparent to those skilled in the art, may be deployed if desired. By way of example, without representing an exhaustive list, liquid detectors based upon chemical, thermal, mechanical, or other physical properties and principles may be substituted to detect leakage fluid. The form of detector  34  shown FIGS. 2 and 3 represents one embodiment for performing the desired fluid detection function.  
         [0022]    With continued reference to FIGS. 2 and 3, the detector  34  is a substantially cylindrical body  36  formed of a hard material such as steel. The body  36  extends forward to a sensor tip  37 , comprising a spaced apart coupled electro-optic transmitter and receiver devices  38 ,  40 . The devices  38 ,  40  are custom made to fit this specific application, but use common use commercially available technology. The transmitter  38  and receiver  40  are separated by a gap  41 . At the rearward end of the body  36  is a threaded bolt coupling  42 . Electrical leads  44  arc routed into the body  36  from the rearward end. A protective covering  46  surrounds the forward tip  37  of the body  36  and is formed of a suitable material such as thermoset or thermoplastic resin. A custom made microprocessor  48  is enclosed within body  36 , of a type using commercially available technology. Output terminals of processor  48  are connected in series to the transmitter  38  and receiver  40  by leads  52 ,  54 , respectively. A battery  50  is further provided to power the microprocessor  48  and electro-optic devices  38 ,  40 .  
         [0023]    Sensor  34 , it will be appreciated, functions to detect the presence of fluid at the tip end  37 . The electronic circuitry of sensor  34  is essentially an open circuit switch. In the absence of fluid, an optical beam is generated by transmitter  38 , traverses gap  41 , and is received by receiver  40 . When the beam is interrupted by, in the subject application, the presence of oil between devices  38 ,  40 , a short circuit is caused and the electronic circuit (switch) closes. Upon closing, an electronic signal is sent via leads  44  to the remote control unit depicted in FIG. 4, located in a control room of the oil tanker or the oil platform. Alternatively, by electronic means commonly known to the industry, the electronic signal may be conveyed to the control unit by wireless transmission by the incorporation of an antenna and transmitter within the sensor  34 . While the sensor  34  is shown to switch to a closed position by the interruption of an optical beam, it will be readily appreciated that alternative means may be designed that, responsive to the detection of fluid, cause an electronic signal to be transmitted to a remote control unit. The signal may be encoded to include an identification of the specific sensor  34  sending the signal in order to pinpoint the location of the leak from the location of the sensor  34 .  
         [0024]    Incorporation of the sensor  34  into a double carcass hose pursuant to the invention is illustrated in FIG. 5. With reference thereto, the end or nipple portion  56  of a hose  26  includes flanges  58  for connecting the hose  26  to an adjacent hose, end-to-end. The inner diameter and outer diameter of the hose varies according to the application. The flange  58  includes assembly apertures  60  extending therethrough. Projecting rearward from flange  58  is a cylindrical portion  62  having anchoring rings  64  projecting from an outer circumference thereof. A cylindrical outer body  66  is provided having a pair of circumferential spaced apart assembly flanges  68 ,  70  projecting outward from an outer circumference thereof. Body  66  and outer carcass  88  both are part of the same outer carcass, forming a unitary piece. Assembly flanges  68  and  70  are not essential to the practice of the invention, although they are built as integral parts of the outer carcass. Integrated within a forward end of the cylindrical body  66  is a collection housing  72 . Housing  72  is a quadrilateral having an internal collection chamber  74  defined along the bottom by portion  62 , a rear end wall  76 , a forward end wall  78 , and an outer wall  80 . The outer wall  80  is provided on the outer circumference with integral anchoring rings  82  for anchoring the outer carcass of the hose  26  to the flange  58 . A sensor mounting aperture  84  extends through the rear end wall  76  of the collection housing  72 .  
         [0025]    The hose  26  is configured having an inner carcass layer  86  for retaining a fluid such as oil flowing through the hose  26 . Pursuant to conventional construction of double carcass hose, an outer auxiliary carcass layer  88  surrounds the inner layer  86  and is capable of retaining the fluid leaking through the inner layer  86 . Tensile reinforcement members  90  are wound around the inner carcass  86 , enclosed within cord layers  92 . The reinforcement structure represented by tensile members  90  and cord ply layers  92  provide structural strength to the fluid conveying inner carcass  86 . A fluid-tight buffering or collection space  94  is positioned between the inner carcass  86  and the outer carcass  88  and extends the axial length of the hose  26 . The space  94  receives and retains fluid leaking through the main inner carcass layer  86 .  
         [0026]    Pursuant to conventional practice, the flange  58  is inserted in one end of the hose body. The cord plies of  92  fit in spaces between the anchoring rings  64  to fasten the hose body to the flange  58 . Similarly a cord ply layer  93  beneath the outer carcass  88  fits in spaces between the anchoring rings  82 . Thus attached, the forward end of the hose segment  26  is fixedly retained within the cylindrical body  66  and is mechanically secured thereto. The collection space  94 , as shown in FIG. 5 extends forward to the annularly disposed and circumferentially extending collection housing  72 . Apertures through the rearward end wall  76  of the collection housing  72  allow fluid from the collection space  94  to migrate into the collection chamber  74 . Accordingly, the collection chamber  74  is in fluid communication with the collection space  94  and fluid leaking from inner carcass  86  will be collected within the collection chamber  74  of housing  72 .  
         [0027]    The sensor  34  is assembled to the forward end wall  78  of the collection housing  72  in the manner shown in FIG. 5. With combined reference to FIGS. 2, 3, and  5 , the sensor body  36  inserts through aperture  84  of end wall  78  and projects into the collection chamber  74 . Threaded bolt end  42  secures the sensor  34  in a fixed, fluid tight connection to the housing  72 . The leads  44  exit from the rearward end of the sensor  34  and may be directed to the oil platform or oil tanker control room. The electro-optic transmitter and receiver  38 ,  40  are thus positioned within the collection chamber  74  at a location generally proximate the rearward end wall  76 .  
         [0028]    It will be readily appreciated that the sensor  34  is consequently in position to sense fluid that escapes the inner hose carcass  86  into the collection space  94  and, thence, migrates into the collection chamber  74 . As the fluid enters the chamber  74  through wall  76  it will penetrate into the gap  41  separating the transmitter and receiver  38 ,  40  and interfere with the optical beam transmitted therebetween. The blockage of the beam by the oil will, as described previously, close the circuit and cause a signal to be transmitted to the control unit. The signal indicates a leak has occurred in the hose segment associated with the sensor. The signal preferably will be coded, or the control unit will be wired, to identify the sensor from which the leak signal originated. In this manner, the leak can be quickly located and repairs or emergency procedures immediately effected. The resin cover  46  over the forward end of the sensor  34  is liquid tight and serves to prevent entry of oil from the collection chamber  74  into the interior of the sensor. The electronic circuitry within the sensor is thus insulated from potentially damaging contamination from the surrounding oil.  
         [0029]    [0029]FIG. 4 illustrates a representative control panel  14  that may be located in the control room of a tanker or oil platform. The panel  14  may be wired with a visual display (for example, a LED) that indicates in general that a leak has occurred. A bank of visual indicators (LED&#39;s)  97  may further be provided and wired to indicate the particular sensor that has been activated by a leak. The location of the leak may thus be ascertained. In addition, an audible alarm set  98  may be provided to emit an audible sound when a leak is detected.  
         [0030]    The sensor system described above satisfies the need of the industry for a means of detecting leakage in a submarine or floating hose line from a remote location, twenty four hours a day and every day of the year, irrespective of weather conditions or lighting conditions. A twenty-four hour operation of the pumping station is thereby facilitated, reducing tanker loading time and making the pumping operation more cost effective. Moreover, because leaks may be remotely detected electronically and monitored from a control room in the tanker or drilling platform, continuous inspection of the oil lines by divers is eliminated. Elimination of risky diving inspections not only reduces the risk of bodily injury to the divers but also significantly reduces operational costs associated therewith.  
         [0031]    Alternative configurations of sensors, as explained previously, may be substituted for the electro-optic sensor described as the preferred embodiment. The electro-optic sensor is preferred because it is relatively simple and resistant to malfunction or breakage. An efficient energy efficient switching circuit may be employed that issues a leak signal when the beam of light is broken. Because the collection housing  72 , sensor  34 , and the collection chamber  74  are advantageously positioned relative to the collection space  94 , there is a high probability that leaking fluid from the inner carcass will be detected and the sensor will issue a leak detection signal as designed. The signal may be conducted to the control unit by hard wire or communicated in a wireless manner if preferred.  
         [0032]    Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.