Abstract:
There is provided a modular scanner and probe holding apparatus for inspection, which consists of an assembly of a plurality of connective links rigidly connected. The connective links are added or removed from the assembly to size the assembly so the assembly extends more than half way around a circumference of a tubular body to be inspected. At least one tail link is connected to an end of the assembly. The tail link is biased by a spring to apply a force against the tubular body to hold the assembly in place. A probe holder link is provided that connects to the connective links and has a probe holder for holding a probe.

Description:
FIELD 
     There is described a modular scanner and probe holding apparatus for use in industrial piping inspections. 
     BACKGROUND 
     In industrial piping environments, there are many situations where defects in materials and/or the welds of the materials must be detected to ensure quality control. The defects may be internal flaws such as cracks, voids, etc. produced during the manufacturing of the material, flaws in the area of a weld due to inadequate welding preparation and/or practice, or surface irregularities due to, in most cases, corrosion. 
     A preferred method for detecting these flaws is called non-destructive testing, or inspection. In non-destructive testing, flaws are detected by various methods such as ultrasonic, x-ray, magnetic particle and electro-magnetic. Historically the majority of pipe or tube inspection has been done by x-ray. More recently ultrasonic methods are being used. 
     The key problem with x-ray inspection is the hazards associated with handling radioactive materials and equipment. The entire work area must be flagged and vacated during inspection which often causes job delays. Conventional Ultrasonic equipment does not require the work area to be vacated but is often too bulky to be used in applications with tight space requirements. Many chemical plants, refineries, and nuclear plants often have piping and tubing spaced closely together. Emerging ultrasonic phased array technology has now made it possible to use ultrasonic inspection in these tight applications. Conventional scanning hardware on the market is too large and bulky to be used in many of the piping and tube application where space is limited. This leaves the operator no choice but to translate the probe along the material&#39;s surface by hand. 
     SUMMARY 
     There is provided a modular scanner apparatus and probe holding apparatus for inspection, which consists of an assembly of a plurality of connective links rigidly connected. 
     The connective links are added or removed from the assembly to size the assembly so the assembly extends more than half way around a circumference of a tubular body to be inspected. At least one tail link is connected to an end of the assembly. The tail link is biased by a spring to apply a force against the tubular body to hold the assembly in place. A probe holder link is provided that connects to the connective links and has a probe holder for holding a probe. 
     The modular scanner, as described above, is readily adjustable to fit different sizes of pipes or tubes. Previously, there was a need to carry different sizes of assemblies to fit different sizes. 
     It is preferred that each of connective links have wheels, which allow the assembly to travel circumferentially around piping and tubing. The assembly has a low profile design enabling inspection of piping and tubing with small radial clearance. 
     Although beneficial results may be obtained just by using the probe, even more beneficial results may be obtained by including an encoder link which connects to the connective links and houses an encoder. The encoder link can be combined with one of the tail links. 
     The connective links can take different forms. However, the preferred form of connective link has a first pivot pin receiver having a first axis, a second pivot pin receiver having a second axis and a rigid connective portion that extends between and connects the first pivot pin receiver and the second pivot pin receiver. The first pivot pin receiver is offset from the second pivot pin receiver with the first pivot pin axially spaced along the first axis in a first direction and the second pivot pin axially spaced along the second axis in a second direction opposed to the first direction. 
     There are different ways in which the connective links can be made rigid. Beneficial results may be obtained when the mating interface between two connective links consists of a cone shaped male portion on one of the connective links and a cone shaped female portion on another of the connective links. When the male portion and the female portion are mated and secured together with a rotatable fastener, the joint becomes rigid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein: 
         FIG. 1   a  is a side elevation view of a scanner assembly. 
         FIG. 1   b  is a perspective view of the scanner assembly of  FIG. 1   a.    
         FIG. 2   a  is a perspective view of a probe holder assembly. 
         FIG. 2   b  is a top plan view of the probe holder assembly of  FIG. 2   a.    
         FIG. 2   c  is a detailed bottom plan view in section of the probe holder assembly of  FIG. 2   a.    
         FIG. 2   d  is a front elevation view of the probe holder assembly of  FIG. 2   a.    
         FIG. 2   e  is a side elevation view of the probe holder assembly of  FIG. 2   a.    
         FIG. 2   f  is a rear elevation view of the probe holder assembly of  FIG. 2   a.    
         FIG. 3   a  is a perspective view of a link assembly. 
         FIG. 3   b  is a top plan view of the link assembly of  FIG. 3   a.    
         FIG. 3   c  is a bottom plan view in section of the link assembly of  FIG. 3   a.    
         FIG. 3   d  is a side elevation view of the link assembly of  FIG. 3   a.    
         FIG. 3   e  is an end elevation view of the link assembly of  FIG. 3   a.    
         FIG. 4   a  is a perspective view of a tail link assembly. 
         FIG. 4   b  is a left side elevation view of the tail link assembly of  FIG. 4   a.    
         FIG. 4   c  is a top plan view of the tail link assembly of  FIG. 4   a.    
         FIG. 4   d  is a top plan view in section of the tail link assembly of  FIG. 4   a.    
         FIG. 4   e  is a front elevation view of the tail link assembly of  FIG. 4   a.    
         FIG. 4   f  is a right side elevation view of the tail link assembly of  FIG. 4   a.    
         FIG. 4   g  is a rear elevation view of the tail link assembly of  FIG. 4   a.    
         FIG. 5   a  is a perspective view of an encoder assembly. 
         FIG. 5   b  is a front elevation view of the encoder assembly of  FIG. 5   a.    
         FIG. 5   c  is a top plan view of the encoder assembly of  FIG. 5   a.    
         FIG. 5   d  is a rear elevation view of the encoder assembly of  FIG. 5   a.    
         FIG. 5   e  is a bottom plan view in section of the encoder assembly of  FIG. 5   a.    
         FIG. 5   f  is a side elevation view of the encoder assembly of  FIG. 5   a.    
     
    
    
     DETAILED DESCRIPTION 
     A modular scanner and probe holding apparatus, generally indicated by reference numeral  10 , will now be described with reference to  FIGS. 1   a  and  1   b . The components making up the scanner apparatus will then be described with reference to the other figures. 
     Structure and Relationship of Parts: 
     Referring to  FIGS. 1   a  and  1   b , the scanner assembly  10  generally provides a means of translating an inspection probe, or probes, circumferentially around cylindrical pipe or tube while outputting positional data. The design is such that the user can quickly and easily configure the scanner  10  for different pipe/tube sizes. The scanner  10  can be assembled to translate either a pair of opposing probes or a single probe, should space be limited. Once configured, the scanner  10  is easily installed by hand simply by clipping it onto the pipe/tube. 
     In the depicted embodiment, the scanner  10  has a left hand assembly  12  and a right hand assembly  14 . The two assemblies are conjoined with one or more bars  16 . Each assembly consists of left or right hand versions of the same components, these being: a probe holder assembly  100 , a link assembly  200 , and a tail link assembly  300 . One of the assemblies also requires an encoder assembly  400  which attaches to a short bar  18 . 
     The scanner assembly  10  is configurable to suit different pipe/tube sizes by adding or removing link assemblies  200 . The joints of the link assemblies  200 , when loosened, are free to rotate and thus allow the scanner assembly  10  to conform to the outer diameter of the pipe/tube. Once the scanner assembly  10  is conformed to the outer diameter of the pipe/tube, the joints are tightened to form a rigid arc-shaped structure. The number of links  200  is chosen so that the wheels of the tail link assembly  300  wrap slightly more than 180 degrees around the outer diameter of the pipe/tube, as shown in  FIG. 1   a . The tail link assembly  300  is spring-loaded so that the scanner assembly  10  can be removed from the pipe or tube by hand. It also offers some adjustability to optimize the number of degrees over 180 that its wheels wrap. If the number of degrees over 180 is too large, the scanner assembly  10  will be too difficult to install/remove. If the number of degrees over 180 is too small, the scanner assembly  10  will not be positively retained on the pipe/tube. In effect, the scanner assembly  10  is a rigid arc-shaped structure with a flexible spring-loaded tail link assembly  300  which retains the scanner assembly  10  on the pipe/tube. The user first configures the scanner assembly  10  to the size of pipe/tube he wishes to scan and then installs it simply by clipping it onto the pipe/tube. 
     The probe holder assembly  100 , link assembly  200 , tail link assembly  300 , and encoder assembly  400  are explained in detail below. 
     Referring to  FIG. 2   a  through  2   f , a preferred embodiment of a probe holder assembly, depicted generally by reference numeral  100 , is depicted. Generally, it provides a means of holding an inspection probe in a manner that allows the probe&#39;s bottom face to remain in proper contact with the inspected material&#39;s surface. To do so, it must provide a force which causes the probe to contact the inspection surface. Also, it must provide two rotational degrees of freedom to ensure proper contact over any irregularities in the inspection surface. 
     In the depicted embodiment, the inspection probe  101  is held by inserting the small round bosses of the probe holder arms  102  into holes in the probe  101 . The small round bosses are free to pivot within the probe holes, thus providing the first required rotational degree of freedom. The probe holder arms  102  slide along a cross bar  106  and are held in place by clamping screws  108 . The center of the cross bar  106  houses a set of bearings  110  through which a pivot pin  112  is inserted. The bearings  110  and the pivot pin  112  provide the second required rotational degree of freedom. A sliding arm  114  is clamped to the end of the pivot pin  112  with a clamping screw  116 . The sliding arm  114  and a swing arm  118  are fastened together with a screw  120  to form an adjustable length swing arm assembly. When the screw  120  is loosened, the sliding arm  114  is free to slide along the swing arm  118  such that the effective swing arm length may be shortened or extended slightly. For most tube sizes, the length of the swing arm  118  would be extended to the maximum. Only for the smallest tube sizes would the swing arm length be reduced, and solely for the purpose of providing clearance between the probe holder and the tail of the scanner since on small tubes the tail of the scanner wraps further around the tube. The swing arm  118  houses a set of bearings  122  through which a shoulder screw  124  is inserted. The bearings  122  and shoulder screw  124  provide an axis of rotation for the adjustable swing arm assembly to swing about. The shoulder screw  124  is threaded into a spindle  126  over which a torsion spring  128  is installed. One end of the torsion spring  128  is inserted into a small hole in the swing arm  118  so that it applies a torque on the swing arm  118 . This torque, when translated through the swing arm assembly and other components, provides the force which causes the probe  101  to contact the inspection surface. The other end of the torsion spring  128  is inserted into a small hole in the spindle  126 . Physical stops for both directions of rotation are preferably built into the swing arm  118  and the swing arm end of the spindle  126  in order to limit the range of rotational freedom of the swing arm assembly. The purpose of the stop that is acted upon by the torsion spring  128  is to reduce the annoyance of the probe  101  swinging further than required during setup and general handling of the scanner, while the stop in the opposite direction is required to prevent the user from over-rotating the swing arm assembly and thus damaging the torsion spring  128 . The range of rotational freedom of the swing arm assembly is designed to be slightly larger than that required to install the scanner on the smallest tube, since the smallest tube requires the largest range of motion. 
     The spindle  126  is preferably fastened to a probe holder link  130  with a screw  132 . A belleville spring stack  134  may be located under the head of the screw  132  and held concentric with a belleville spring retainer  136 . The mating interface between the spindle  126  and the probe holder link  130  is cone shaped so that the joint operates like a cone-brake mechanism. The axial force clamping the two members together is directly related to the torque capacity of the joint. The clamping force of the screw  132 , which is controlled by the amount of deflection of the belleville spring stack  134 , may be factory set such that the joint is capable of holding more that the torque output of the torsion spring  128 , but not more than what is easily overcome by hand. This limited-slip joint allows the user to easily reposition the range of rotational freedom of the swing arm without tools. This is beneficial since the spring-loaded probe can be rotated out of the way while the user configures the rest of the scanner. 
     Wheel assemblies  138  are located as shown and provide smooth rolling along the inspection surface. A self-captured screw  140  is retained in the probe holder link  130  and is used to attach the probe holder assembly  100  to the link assemblies  200 , which form the structure of the scanner. 
     Referring to  FIG. 3   a  through  3   e , a preferred embodiment of the link assembly is identified in general by reference numeral  200 . Two link assemblies  200  are shown connected together. The main component is the link  202  to which are attached two wheel assemblies  138 . A screw  204  retains one of the wheel assemblies  138 , and a self-captured screw  140  retains the other and holds the link assemblies  200  together. Each connective link has a first pivot pin receiver  142  having a first axis  144  and a second pivot pin receiver  146  having a second axis  148 . The first pivot pin receiver  142  is offset from the second pivot pin receiver  146 . The mating interface between the two link assemblies  200  is cone shaped with a male portion  150  and a female portion  152  so that the joint is rigid, without play, and capable of being tightened easily with one screw  140 . Prior to making the joint rigid, the link  202  may be pivoted about the screws  140 , which act as a pivot pin until tightened. 
     the first pivot pin receiver being offset from the second pivot pin receiver with the first pivot pin axially spaced along the first axis in a first direction and the second pivot pin axially spaced along the second axis in a second direction opposed to the first direction. 
     Referring to  FIG. 4   a  through  4   g , a preferred embodiment of the tail link assembly is identified in general by reference numeral  300 . Generally, it is the final link in the scanner assembly and its purpose is to provide the retaining force which holds the scanner assembly  10  on the pipe/tube. It also provides an adjustment which allows the operator to optimize the degrees over 180 that the tail link assembly  300  wraps. 
     In the depicted preferred embodiment, it has a tapered mount  302  which assembles to the last link assembly  200  with a self-captured screw  140 . An adjustable arm  304  is fastened to the tapered mount  302  with a screw  306 . When the screw  306  is loosened, the user can slide the adjustable arm  304  relative to the tapered mount  302  so that the effective length of the arm may be lengthened or shortened. The adjustable arm  304  has a female taper feature into which a tapered spindle  308  is fastened with a screw  310 . A belleville spring stack  312  is retained with a spring retainer  314  and is used to create a limited slip joint similar to the probe holder. The limited slip joint allows the user to adjust the position of the tail link assembly wheels by hand. It also protects the components of the tail link assembly  300  from the potentially damaging forces induced when the user installs the scanner assembly onto the pipe/tube. Rather than bend the weakest scanner components, the tail link assembly joint will simply slip until the required opening is achieved for passing over the largest portion of the pipe/tube. 
     As depicted, a swing block  316  is fastened to the tapered spindle  308  with a shoulder screw  318  and a set of bearings  320 . Two torsion springs  322  are mounted on a mandrel  324  and apply a torque on the swing block  316 . The mandrel  324  is keyed to the tapered spindle  308  so that the reaction torque is transmitted from the mandrel  324  to the tapered spindle  308 . A wheel block assembly  326  is fastened to the swing block  316  with a pair of screws  328  and houses a set of bearings  330  through which a shaft  332  is inserted. An inner wheel  334  and outer wheel  336  are retained on the shaft with set screws  338 . Although the scanner may be moved around the pipe/tube by hand, smoother and more controlled operation may be achieved with the addition of an optional motor  340 , which may be inserted into the swing block  316  and retained with a cap  342 . The shaft of the motor  340  is keyed together with the shaft  332  which would in turn rotate the inner wheel  334  and outer wheel  336 , driving the scanner around the pipe/tube. 
     Referring to  FIG. 5   a  through  5   f , a preferred embodiment of the encoder assembly is identified in general by reference numeral  400 . Generally, it is the component of the scanner which provides the positional data to the user. In the depicted embodiment, it clips onto a short bar  18  with a clip  402  which houses a bearing set  404  though which is inserted a pin  406 . The pin  406  is retained in a housing block  408  with a set screw  410 . A torsion spring  412  exerts a torque on the housing block  408  relative to the clip  402  so that when the encoder assembly  400  is installed on the scanner assembly  10 , the wheel of the encoder assembly is held in constant contact with the inspection surface. Portions of the housing block  408  extend towards and overlap the clip  402  to limit the relative rotation between the clip  402  and the housing block  408 . The housing block  408  houses a bearing set  414 , through which is inserted a wheel shaft  416 . A screw  418  retains the wheel shaft  416  within the bearings  414 . A diametrically magnetized magnet  420  is installed in the end of the wheel shaft  416  and provides a magnetic signal to the encoder module  422 . The encoder module  422  decodes the magnetic signal and transmits it down its cable. 
     In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. 
     The following claims are to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. It is to be understood that, within the scope of the following claims, the invention may be practiced other than as specifically illustrated and described.