Abstract:
An ultrasonic inspection system useful for inspecting a tubular member provides for the use of ultrasonic transducer assembly for detecting weld flaws or other out-of range conditions in the tubular member. According to the invention, the tubular member is positioned horizontally on a rolling carriage and a predetermined amount of sound-conductive fluid is deposited into the tubular member. Wide rings secured to opposing open ends of the tubular member prevent the liquid from escaping, while forming a barrier for retaining a given level of liquid inside the tubular member. The transducers are submerged in the liquid and transmit/ receive sonic booms from reflected medium inside the tubular member. The transducers are connected to a computing control unit, which receives signals generated by the transducers and creates a report of any out-of range condition.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an inspection apparatus, and more particularly, to an inspection apparatus suitable for inspecting tubular members, such as pipes. 
     Pipelines of various lengths and sizes are widely used in a variety of industries, transporting oil, gas, particulate matter, small solids suspended in fluids and other materials. Pipelines are installed underground and underwater, which results in the pipelines being subject to often harsh environmental conditions including temperature variations, deep sea pressures, and the like. With time, the environment causes pipelines to weaken, sometimes crack along the weld seams, often times corrode. Should the pipeline integrity become compromised, the material traveling along the pipeline may escape and cause substantial damage to the environment. 
     As a consequence, considerable efforts are dedicated to the inspection of the pipes during manufacturing process. Visual inspection may serve its purpose when the defects are visible. However, visible inspection has its limitations particularly inspection of the inner surface weld may become inefficient and expensive. 
     The industry has developed a variety of tools to facilitate detection of weld defects in tubular members. Some inspection devices use magnetic force created by magnetizing coils for inducing a magnetic field in the ferrous pipe. Inspection sensor measures changes in the induced magnetic field and produce signals representative of those changes. An analog-to-digital converter digitizes the measured signals representing the changes in the induced magnetic field. Other devices employ ultrasonic inspection methods that use sonic beams to locate defects in tubular members. Some ultrasonic devices use transducers that transmit sonic beams and receive reflected beams from inner and outer surfaces of the pipe, and from defects of the tubular members. In general, this technology is based on the speed of sound in metal and the fact that a sound wave will reflect (“echo”) from medium interfaces 
     Conventional techniques involve spraying of water on the outside of the pipe and then applying the sonic boom to uncover potential defects in the weld. However, this method relies largely on the experience of the technician performing the test. Human error can affect the results of the test, leading to missed imperfections in the weld. Therefore, a need exists for an inspection apparatus capable of providing information of defects in a pipe and capable of being easily operated during an inspection. 
     The present invention contemplates elimination of drawbacks associated with conventional technique and provision of an improved system and method of tubular members testing and inspection that is easy to use and operate. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of this invention to provide an apparatus of for inspecting tubular members. 
     It is another object of the invention to provide a system and method for inspecting tubular members using ultrasound technology. 
     It is a further object of the invention to provide a system and method of inspecting welds made in the tubular members using ultrasound technology. 
     These and other objects of the invention are achieved through a provision of an ultrasonic inspection system useful for inspecting a tubular member provides for the use of ultrasonic transducer assembly for detecting weld flaws or other out-of range conditions in the tubular member. According to the invention, the tubular member is positioned horizontally on a rolling carriage and a predetermined amount of sound-conductive fluid is deposited into the tubular member. Wide rings secured to opposing open ends of the tubular member prevent the liquid from escaping, while forming a barrier for retaining a given level of liquid inside the tubular member. The transducers are submerged in the liquid and transmit/ receive ultrasonic signals from reflected medium inside the tubular member. The transducers are connected to a computing control unit, which receives signals generated by the transducers and creates a report of any out-of range condition. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to the drawings, wherein like parts are designated by like numerals, and wherein 
         FIG. 1  is a perspective end view of a tubular member mounted on a carriage of the apparatus of the present invention. 
         FIG. 2  is a perspective side view of the apparatus of the present invention. 
         FIG. 3  is an end view of the tubular member being tested, showing position of ultrasonic transducers. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings in more detail, numeral  10  designates the pipe testing apparatus of the present invention. The apparatus  10  comprises an upright pedestal  12  positioned on the ground  14  at or near railway tracks  16 . The pedestal  12  can be elevated using the legs  18  for alignment with a tubular member being tested and positioned on a carriage. An elongated beam  20  is secured at a proximate end  22  thereof to the pedestal  12 . The beam  20  is cantilevered from the pedestal  12  and extends transversely to an attachment plate  21  secured to a front surface  23  of the pedestal  12 . The length of the beam  20  is selected to approximate the length of a tubular member  30  being inspected. A supporting bracket  26  is secured to a distant end  24  of the beam  20 . The bracket  26  extends downwardly from the beam  20 , supporting the array of ultrasonic transducers  30  by a free end thereof. 
     A carriage assembly  40  for laterally supporting a tubular member is mounted on rotating wheels  42 . The carriage assembly  40  is configured for movement along the tracks  16  in the direction of arrow  41  and back while being supported by the wheels  42 . Alternatively, the wheels  42  may be adapted for movement on the ground. The carriage assembly  40  comprises a generally rectangular frame  46  having a plurality of reinforcing beams  48  extending between a first side  47  and a second side  49  of the frame  46 . 
     A first set of rollers  50 ,  51  is secured on the frame  46  adjacent a proximate end  43  of the carriage assembly  40 . A second set of rollers  52 ,  53  is positioned adjacent a distant end  45  of the carriage assembly  40 . The first set of rollers  50 ,  51  are spaced from each other and are oriented in a generally parallel position. The second set of rollers  52 ,  53  is similarly spaced from each other and oriented in parallel relationship. The rollers  50 ,  52  are aligned along the same plane and are positioned adjacent the side  47  of the frame  46 . The rollers  51 ,  53  are similarly aligned along the same plane and are positioned adjacent the side  49  of the frame  46 . 
     The rollers  50 ,  51 ,  52 , and  53  each have rotating members  54  (only one rotating member  54  is shown in  FIG. 1 ) that are configured for supporting a tubular member  30 , while allowing the tubular member  30  to be rotated about its axis in the direction of arrow  62  during testing. The rollers  50 ,  51 ,  52 , and  53  may be connected to an external power source for imparting rotation on the rotating members  54 , if desired. 
     Each ultrasonic transducer  30  is provided with cables  32 , which operationally connect the transducers  30  to a sound generating, processing and control unit  34 . The control unit  34  may be mounted on the pedestal  12 , if desired. As can be seen in  FIG. 3 , each of the transducers  30  comprises a generally rectangular housing that is adapted to be positioned inside the tubular member  60  in close proximity to the wall of the tubular member  60 . An optional block  36  may be provided for orienting respective transducer housing inside the pipe  60 . The blocks  36  may be formed as wedges adapted for resting on the inside wall of the pipe  60 . 
     A ring-shaped member  70  is positioned on a proximate open end  64  of the tubular member  60 . The inner circumferential edge  72  of the ring  70  extends inwardly toward the center of the pipe  60 . A similar ring-shaped member  74  is positioned on a distant open end  66  of the pipe  60 . An inner circumferential edge  76  of the ring  74  extends a distance toward the center of the pipe  60 . The rings  70 ,  74  may be formed of rubber or other non-corrosive material. The rings  70 ,  74  may have a width of about 2-3″, or other width sufficient to flood a portion of the pipe interior and submerge the transducers  30 . 
     The rings  70  and  74  form a watertight circumferential wall, or barrier that allows water or other sound-conductive liquid to be retained in the pipe  60  during testing. As can be seen in  FIGS. 2 and 3 , the water level  80  does not extend beyond the inner edges  72 ,  76  of the rings  70 ,  74 . At the same time, the transducers  30  become partially or entirely submerged when positioned inside the tubular member  60 . 
     In operation, the apparatus  10  is delivered to a testing site, where the pipes  60  are welded. The weld seams  61 , usually made on a spiral along the length of the pipe  60  are inspected using the system of the present invention. The tubular member  60  is positioned on the carriage assembly  40 , on top of the rolling members  54 . The rings  70  and  74  are secured on the ends  64 ,  66  of the pipe  60 , respectively. Water is then deposited into the cavity defined by the inside wall of the pipe  60  and the inner edges  72 ,  76  of the rings  70 ,  74 . 
     The carriage is then moved toward the pedestal  12 , allowing the beam  20  to extend inside the tubular member  60  and to suspend the transducers  30  in a submerged position, below the water level  80 , inside the tubular member  60 . The cables  32  are connected between the transducers  30  and the computing control unit  34 . Rotation is then imparted on the pipe  60 , allowing the water to be moved by gravity inside the pipe  60 . At the same time, the control unit  34  energizes the transducers  30  to send and receive sound waves. 
     In general, the instant method is based on the speed of sound in metal and water, as well as the fact that a sound wave will reflect (“echo”) from medium interfaces. Thus by propagating a sonic wave in the water and by measuring the time it takes for echo of that wave to return from an interface, it is possible to determine the precise distance to the interface. Such interface may be the weld  61  on the wall of the tubular member  60 . In order to determine the wall thickness (or insufficient weld thickness) in the tubular member  60  about the whole area of the tubular member  60 , the tubular member is rotated about its axis and advanced longitudinally in relation to the transducers  30 , which periodically “fire” and effectively sample the weld thickness under the transducers  30  at the time. As the pipe  30  advances a stream of data points, each one representing a weld quality, measurement is generated. 
     The data resulting from testing is displayed on a screen of the control unit  34 . Out-of-range values can be detected either by human reading or by a computer detection of out of range values. From such data the general location of a suspected defect along the length of the weld in the tubular member, its magnitude and direction (whether too thin or too thick) can be determined. The operator can then identify the pipe as acceptable for use or as requiring repairs. 
     To facilitate generation of readable data, the blocks  36  can be inclined so that the transducers  30  are held in a position relative to the pipe surface to transmit a short duration sonic wave pulse of beamed energy into the wall of the pipe at an angle such that a flaw or discontinuity in the weld  61  causes the waves to be reflected back and produce a signal indicative of an out-of-range condition. 
     In one of the preferred embodiments, the transducers are oriented to send sonic waves in opposite directions, so that a given defect that may be invisible to one transducer  30  looking at it from one direction becomes visible to a second transducer  30  looking at it from the opposite direction. Once the inspection of the pipe  60  is completed, the tubular member  60  is removed from the carriage  40 , and another tubular member is positioned on the carriage  40  for inspection. The report generated by the control unit  34  is analyzed. If a defect is found, the tubular member  60  is repaired; if no defects are detected, the pipe  60  may be accepted for field use. 
     The apparatus of the present invention allows inspection of an entire length of the tubular member  60 , end-to-end. Depending on the particular application, the length of the beam  20  can be modified in order to cover the length of the pipe  60  being inspected. Combined with the ability of the carriage  40  to travel longitudinally, the apparatus of the instant invention allows defection of out-of-range conditions along the walls of the tubular member regardless of the size of the pipe. 
     Many changes and modifications can be made in the design of the present invention without departing from the spirit thereof. I therefore pray that my rights to the present invention be limited only by the scope of the appended claims.