Abstract:
A digital radiographic tool with drive car for moving along track sections attached longitudinally to a pipe is shown. The drive car carries (1) a collimator on one side of the pipe for projecting x-rays or gamma rays on said pipe and (2) a linear digital array on an opposing side of the pipe for collecting x-rays or gamma rays that have passed through the pipe. The collected rays are processed to indicate any defects in the pipe. The digital radiographic tool is adjustable to allow inspection of pipes that have obstructions adjacent thereto.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the inspection of pipes, and more particularly, to a device and/or method of using x-rays or gamma rays transmitted through a pipe and collected on the other side of the pipe in a digital detector array to determine if there are defects in the pipe. 
       BACKGROUND OF THE INVENTION 
       [0002]    Pipelines are commonly used to transport material such as gas, oil, slurry or similar substances over long distances. Such pipelines are normally made out of metal and are commonly joined together with welds. In refineries, pipelines are used to transport material from one portion of the refinery to another. The pipeline may (or may not) be covered with insulation. 
         [0003]    Such pipelines may corrode and, if the corrosion is not detected early enough, the pipelines may start to leak. If the leak is not detected early, catastrophic results may occur, including fires and/or explosions. Preferably, the corrosion is detected before a leak ever occurs. 
         [0004]    Non-destructive testing, including the use of x-rays or gamma rays penetrating the pipeline, is used to determine if a pipeline has defects therein as may typically be caused by corrosion. U.S. Patent Publication No. US 2012/0201347 A1, published on Aug. 9, 2012 by Prentice et al. and assigned to Shawcore Ltd. shows a method and apparatus for inspecting pipelines to determine if there are any defects in a pipeline. However, the Prentice patent is difficult to install and requires access to the entire circumference of the pipeline. If a pipeline is in a refinery and is supported on support beams, the Prentice invention cannot inspect the pipe where the pipe touches the support beam. 
         [0005]    In pipelines, if the pipeline is buried, non-destructive testing of the buried pipeline is normally made by sending a pig through the pipeline. The pig is typically made up of (a) a drive package, (b) a flux loop that does the sensing and (c) a recorder package. Using such a pig, the entire Trans Alaska Crude Oil Pipeline was tested in 1997. However, for many pipelines, especially in refineries or processing plants, a pig cannot be run through the pipeline. Also, many of the pipelines are covered with insulated material which prevents direct access to the pipeline. 
         [0006]    The purpose of the non-destructive testing is to use a non-invasive technique to determine the integrity of a pipe or quantitatively measure any corrosions or defects in the pipe. Non-destructive testing inspects and measures without doing harm to the pipe. There are many different ways of non-destructive testing, including, but not limited to, (a) acoustical emissions, (b) ultrasonic, (c) eddy current, (d) magnetic measurements, (e) microwave, (f) flux leakage or (g) x-ray. The use of x-rays or gamma rays is one of the more common techniques for non-destructive testing. In the use of x-ray or gamma ray technology for non-destructive testing, the pipe being tested is placed between the radiation source and a detector. The less radiation that reaches the detector, the better the pipe. The more radiation that reaches the detector, the more wear or corrosion in the pipe. 
         [0007]    In industrialized countries such as the United States, many refineries or processing facilities were built years ago. Over time, corrosion or erosion can cause the pipes in the plant to wear thin and eventually leak. If a pipe leaks, depending upon what is being moved through the pipe, the leak can cause catastrophic results. The detection of a thin section of pipe before it leaks can be very critical. 
         [0008]    The use of non-destructive testing for pipelines has become so common that standards have been developed by ASTM International. A collection of ASTM standards under “Radiology (X and Gamma) Method” have been developed. 
         [0009]    One of the entities that has performed non-destructive testing on insulated pipes in the past is IHI Southwest Technologies, Inc. located in San Antonio, Tex., assignee of this invention. IHI has developed digital radiograph tools for detecting internal and external corrosion in insulated piping. Generally, a radiation source will create a radiation beam that penetrates a pipe under test. The radiation beam will penetrate not only the pipe, but also insulation there-around. A detector array is located on generally the opposing side of the pipe being inspected using a radiation source. In this manner, the detector array can determine if there is any corrosion and the severity of the corrosion. However, the prior systems developed by IHI were very complex and hard to move along a pipe being inspected to give good results. Also, dead zones would occur that were not being penetrated by the radiation. Because of the difficulty in installation and maneuverability of the prior digital radiographic imaging by IHI, it was difficult to eliminate the dead zones. The prior developed digital radiographic tool requires a lot of time to install and operate. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    It is an object of the present invention to provide for digital radiographic imaging of pipes. 
         [0011]    It is another object of the present invention to provide a simplified, easy to use, structure for a digital radiograph tool that can be used for inspection of pipes. 
         [0012]    It is yet another object of the present invention to provide a method and apparatus for using a digital radiograph tool for the inspection of pipes, particularly pipes that are insulated. 
         [0013]    It is still another object of the present invention to provide an apparatus and method for the inspection of pipes using x-rays or gamma rays, which x-rays or gamma rays after passing through a pipe being inspected are detected and collected in a digital detector array. After processing the images received in the digital detector array, a determination of defects, location of defects, and severity of the defects is made. 
         [0014]    A radiation source of x-rays or gamma rays is projected through a pipe under test. As the radiation source is moved along the pipe, a digital detector array is also moved along the pipeline, but on an opposing side from the radiation source. The amount of radiation that hits the digital detector array determines, after processing, if there is corrosion or other defects at predetermined points along the pipe. The more of the radiation signal that passes through the pipe, the greater the probability is of a defect in the pipe, such as corrosion. The stronger the signal reaching the digital detector array, the greater the probability of a defect. 
         [0015]    The digital radiograph tool of the present invention has a track assembly attached to the pipe being inspected. On the track assembly is mounted a car assembly which has attached thereto an arm assembly. On the opposite end of the arm assembly is a linear digital array that is located adjacent to the pipe being inspected. Also connected to the car assembly is a collimater assembly which is located as close as possible to the opposing side of the pipe being tested from the linear digital array. 
         [0016]    By making the arm assembly expandable and the collimater assembly adjustable, different size pipes can be accommodated. Also, the collimater assembly, track assembly, car assembly and linear digital array can be adjusted on the pipe as necessary to overcome obstructions that may be adjacent to (or touching) the pipe being inspected. By keeping the digital radiographic tool small and fully adjustable, it is much easier to inspect pipes with a minimum of cost and personnel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of a digital radiographic tool made according to the present invention being used to inspect a pipe. 
           [0018]      FIG. 2  is a left end view of  FIG. 1 . 
           [0019]      FIG. 3  is an elevated side view of  FIG. 1 . 
           [0020]      FIG. 4  is a block diagram of the electronic controls of the digital radiographic tool illustrated in  FIG. 1 . 
           [0021]      FIG. 5   a  is a top view of the track assembly. 
           [0022]      FIG. 5   b  is an elevated side view of the track assembly. 
           [0023]      FIG. 5   c  is a top view of separate sections of the track assembly. 
           [0024]      FIG. 5   d  is an end view of  FIG. 5   a.    
           [0025]      FIG. 6   a  is a perspective view of the car assembly. 
           [0026]      FIG. 6   b  is an elevated side view of  FIG. 6   a.    
           [0027]      FIG. 6   c  is a side view of  FIG. 6   a  with the car body being separated from the linear bearing chassis. 
           [0028]      FIG. 6   d  is an end view of  FIG. 6   a , but with the removable pins removed. 
           [0029]      FIG. 6   e  is an exploded side view of  FIG. 6   a.    
           [0030]      FIG. 7   a  is an end view of the fully collapsed arm assembly. 
           [0031]      FIG. 7   b  is a side view of  FIG. 7   a.    
           [0032]      FIG. 7   c  is the opposite end view of the fully collapsed arm assembly from the one shown in  FIG. 7   a.    
           [0033]      FIG. 7   d  is the same view as  FIG. 7   c , but with the arm assembly fully extended. 
           [0034]      FIG. 8   a  is an end view of a collimator assembly. 
           [0035]      FIG. 8   b  is a side view of the collimator assembly. 
           [0036]      FIG. 9  is a bottom sectional view of two tracks of the track assembly connected together. 
           [0037]      FIG. 10  is a perspective view of the stepper motor illustrating the gear connections thereto. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0038]    Referring now to  FIGS. 1 ,  2  and  3  in combination, a pipe  10  is being inspected by a digital radiographic tool  12 . The digital radiographic tool  12  has a track assembly  14  with a drive car  16  mounted thereon. The drive car  16  can move back and forth along the track assembly  14 . 
         [0039]    Attached to one side of the drive car  16  is an arm assembly  18 . On the distal end of the arm assembly  18  is mounted a linear digital array  20 . On the opposite side of the drive car  16  from the arm assembly  18  is attached the collimator assembly  22 . 
         [0040]    The drive car  16  of the digital radiographic tool  12  moves back and forth along pipe  10  on the track assembly  14 . As the drive car  16  moves back and forth, it carries the collimator assembly  22  which generates x-rays or gamma rays projected towards the pipe  10 . On the opposite side of the pipe  10  from the collimator assembly  22 , the x-rays or gamma rays are collected in the linear digital array  20 . 
         [0041]    Referring now to  FIG. 4 , a pictorial block diagram of the pipe  10  being inspected by a digital radiographic tool  12  is shown. The digital radiographic tool  12  includes the arm assembly  18  and the collimator assembly  22 . 
         [0042]    Power is supplied to the digital radiographic tool  12  by 115V power supply  24  which connects to a power supply and control box  26  via 115 VAC power line  28 . Simultaneously, the 115V power supply  24  supplies power to a user laptop  30  via power line  32 . 
         [0043]    The power supply and control box  26  has a joy stick  34  connected to a stepper motor  36  within the drive car  16  (see  FIGS. 1 ,  2  and  3 ) via drive signal connection  38 . The stepper motor  36  provides a  75 V drive signal  40  to stepper motor  42 . The stepper motor  42  through a gear box  44  drives gears  46  that mechanically connect with track assembly  14 . 
         [0044]    As the drive car  16  (see  FIGS. 1 ,  2  and  3 ) is driven along track  14 , the collimator assembly  22  emits x-rays (or gamma rays)  48  which penetrate pipe  10 . The x-rays  48  that penetrate the pipe  10  are then collected by the linear digital array  20 . The signals collected by the linear digital array  20  are fed via Ethernet data connection  50  to the user laptop  30 . From the laptop  30 , USB data connection  52  connects to power supply and control box  26 . Also, the linear digital array  20  receives its power from power supply and control box  26  via power connection  54 . 
         [0045]    While many different types of software can be used, Applicants have found that iX-Control by Shaw Pipeline Systems to be a good software to use. Using the iX-Control software, the user laptop  30  can give the commands to the power supply and control box  26  to move the digital radiographic tool  12  a certain distance along pipe  10  and it will occur. By having the collimator assembly  22  emit x-rays  48  as the digital radiographic tool  12  is moved along the track assembly  14 , radiated signals will be detected by the linear digital array  20 . The user, through the user laptop  30 , will set the start point to determine the distance of movement and speed while recording data. The recorded data will indicate whether pipe  10  does (or does not) have defects therein such as would be caused by corrosion. Even if the pipe  10  is surrounded by insulation, the x-rays  48  will penetrate the insulation and the pipe  10  sufficient to give a table recording or a pictorial recording as illustrated in the user laptop  30 . If an emergency stop is necessary, an emergency stop button  56  is provided on the power supply and control box  26 . 
         [0046]    Referring now to  FIGS. 5(   a ), ( b ), ( c ) and ( d ), the track assembly  14  will be explained in more detail. Track assembly  14  is made up of modular sections  58  and  60  (see  FIG. 5   c ). As many more sections as may be necessary can be used. Applicants have found that section links of 2 ft. and/or 4 ft. to be ideal. The modular sections  58  and  60  are aligned by alignment pins  62  at each end of the linear rails  64 . Opposing ends of the linear rail  64  from the alignment pins  62  have holes therein (not shown) to receive the alignment pins  62 . The modular sections  58  and  60  are held together by latch  66 . 
         [0047]    The linear rails  64  are mounted on a track frame  68 . Contained within the track frame  68  is a gear rack  70  for meshing with a gear as will be subsequently described. On each end of the modular sections  58  and  60  are located idle roller wheels  72 . The idle roller wheels  72  may be held on the track frame  68  by any conventional means such as by bearings and axles. Each of the modular sections  58  and/or  60  are held to the pipe  20  by tie-downs  75 that extend through tie-down slots  74  and around pipe  10  (see  FIGS. 1-4 ). 
         [0048]    Referring now to  FIG. 9  in conjunction with  FIGS. 5(   a ), ( b ), ( c ) and ( d ), a bottom view with the latch  66  is illustrated.  FIG. 9  is a cross-sectional view of  FIG. 5(   b ) along section lines  9 - 9 . The latch  66  is pivotally mounted on pivot pin  76 . If a user presses release button  78 , the latch  66  will be pivoted about pivot pin  76  so that it disengages from latch stop  80 . The idle roller wheels  72  are shown threadably connected to the track frame  68  by wheel screws  82 . 
         [0049]    Referring now to  FIGS. 6(   a )-( e ), the drive car  16  will be discussed in detail. The drive car  16  has a stepper motor  42  that connects through a coupler  82  to drive the worm  84  that will mesh with worm gear  86  (see  FIG. 6   e ). The worm gear  86  is connected by drive shaft  88  to the spur gear  90 . Spur gear  90  meshes with the gear rack  70  (shown in  FIGS. 5(   a ), ( c ) and ( d )) to drive the entire drive car  16 . Power for the stepper motor  42  is received through the drive signal connection  38  connecting through the drive signal input  92 . 
         [0050]    Attached to the top of the car body  94  is the stepper motor driver  36 . A waterproof cover  96  seals the stepper motor driver  36  inside of car body  94 . Front cap  98  enclosed the front of car body  94 . Pin holes  100  and  102  extend through car body  94  to receive removable pins  104  and  106 , respectively, there through. Removable pin  104  and  106  are spring-loaded to be removed upon pushing end buttons  108  or  110 , respectively (see  FIGS. 6   d  and  6   e ). 
         [0051]    T-slots  112  are formed on both sides and in the top of the car body  94 . The T-slots  112  allow T-bolts (not shown) to be inserted therein on which items can be attached to the drive car  16 . For example, the stepper motor driver  36  is contained in stepper motor driver housing  114  by means of T-slots  112  in the car body  94 , which T-slots are located directly below the stepper motor driver housing  114 . 
         [0052]    Referring to  FIG. 6   c , a linear bearing chassis  116  is shown disconnected and below from the car body  94 . The linear bearing chassis  116  is connected to the car body  94  by removable pins  104  and  106  extending through pin holes  100  and  102 , respectively (see  FIG. 6   d ). The spur gear  90  extends below the drive car  16  as is illustrated in  FIG. 6   b . Hence, the spur gear  90  meshes with the gear rack  70  of the track assembly as shown in  FIGS. 5   a, c  and  d.    
         [0053]    The bottom of the linear bearing chassis  66  has linear bearings  118  mounted there below. The linear bearings  118  receive the linear rails  64  (see  FIGS. 5   a, b, c  and  d  and  FIG. 6   d ) therein. To reduce friction between the linear bearings  118  and the linear rail  64 , the linear bearings  118  have bearing liners  120  therein. 
         [0054]    Referring now to  FIGS. 7   a - d,  the arm assembly  18  is shown in more detail. The arm assembly  18  has a radial arm plate  122  on either side thereof. In  FIGS. 7   a, b  and  c,  the arm assembly  18  is fully collapsed. In  FIG. 8   d , the arm assembly  18  is fully extended with an intermediate telescoping T-slot frame  124  and an upper telescoping T-slot frame  126 . The intermediate telescoping T-slot frame  124  is held in position by thumb screws  128 . The upper telescoping T-slot frame  126  is held in position by thumb screws  130 . On the upper end of the arm assembly  18 , a T-slot clamp  132  may be pivoted by loosening clamping L-handles  134 . By loosening clamping L-handles  134 , the T-slot clamp  132  may be pivotally adjusted (see  FIG. 7   b ). 
         [0055]    At the bottom of the arm assembly  18  and mounted between radial arm plates  122  is the linear digital array  20 . The linear digital array  20  has an Ethernet data connection  50  and a power connection  54 . 
         [0056]    Connected in the T-slot clamp  134  is the T-slot mount  136  of the collimator assembly  22  (see  FIGS. 8   a  and  b ). The first angle adjustment  138  of the collimator assembly  22  is provided by loosening clamping L-handle  140 . Held in position by first clamping L-handle  140  is a first collimator arm  142  and a second collimator arm  144 , on either of which can be mounted collimator housing  146 . Thumb screw  148  secures the collimator housing via slot  150  on the second collimator arm  144 . The thumb screw  148  allows for linear adjustment  152  of the collimator housing  146 . Also, the collimator housing  146  could be mounted in slot  154  of first collimator arm  142 . 
         [0057]    A second angle adjustment  156  is provided between first collimator arm  142  and second collimator arm  144  by a second clamping L-handle  158 . Inside of the collimator housing  146  is located the collimator  160 . A shim slot  162  is also provided if minor adjustments to the collimator  160  need to be made. 
         [0058]    By use of the arm assembly  18  as described in  FIGS. 7   a - d  and the collimator assembly  22  as described in  FIGS. 8   a  and  b,  the adjustability of the digital radiographic tool  12  is illustrated. This adjustability feature allows either the collimator  160  or the linear digital array  20  to be adjusted to reach under and/or around pipe supports. Due to the adjustability features, various diameter pipes can be accommodated. The adjustability features of the digital radiographic tool  12  allow a single person to operate the tool and to inspect a greater percentage of the pipe than prior inspection devices. 
         [0059]    Referring now to  FIG. 10 , connection of the stepper motor  42  through coupler  82  to the worm  84  is illustrated in more detail. The worm  84  meshes with the worm gear  86  mounted on drive shaft  88 . As the worm  84  turns, the worm gear  86  also turns and rotates drive shaft  88  on which spur gear  90  is also mounted. The turning of the spur gear  90  which meshes with the gear rack  70  (see  FIG. 2 ), moves the drive car  16  and the entire digital radiographic tool  12  along the track assembly  14 .