Abstract:
An electromagnetic flaw detection apparatus for inspection of a tubular has a frame, a first electromagnetic field generator connected to the frame, a second electromagnetic field generator connected to the frame on an opposite side of the tubular from the first electromagnetic field generator, first and second sensors positioned with respect to the frame so as to be movable between a first position away from the tubular and a second position in proximity to the tubular, and a tubular conveyor cooperative with the frame for moving the tubular in a helix path along a longitudinal axis of the tubular toward and through the frame. The first and second sensors are suitable for detecting flux leakage from the magnetic flux field generated by the electromagnetic field generators.

Description:
RELATED U.S. APPLICATIONS  
       [0001]     Not applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable.  
       REFERENCE TO MICROFICHE APPENDIX  
       [0003]     Not applicable.  
       FIELD OF THE INVENTION  
       [0004]     The present invention relates to the electromagnetic flux leakage inspection of tubulars. More particularly, the present invention relates to apparatus and methods whereby a fixed frame contains the electromagnetic flux generators and sensors relative to a tubular translatably passed therethrough.  
       BACKGROUND OF THE INVENTION  
       [0005]     Continuous tubular strings formed of connectable tubular sections or elements, such as production tubing strings, strings of drill pipe and casing strings, are used in the drilling, completion and production of subterranean oil and gas wells. The tubular elements comprising such strings are subject to mechanical damage when the tubular elements are located within the well and are also subject to the action of corrosive fluids which may be contained within the tubular elements or which may be transported through the tubular string between the well surface and a downhole location. It is therefore advantageous that the individual tubular elements comprising a tubular string be inspected periodically. Commonly, tubular elements or tubular sections are inspected for defects after the tubing string is removed from the well. Conventional inspection of tubular sections normally occurs to the individual tubing sections comprising the tubing string. Defect inspections are conventionally performed on a section-by-section basis.  
         [0006]     A number of techniques exist for determining the presence of a defect in a tubing section. For example, the precise location of internal and external radially extending and three-dimensional defects, including slug inclusions, mechanical damage, corrosion pitting and fatigue cracks, has been determined by flux leakage techniques in which a longitudinal magnetic field is induced by one or more magnetic induction coils. Surface riding detectors are located around the tubing and the maximum signal is recorded to precisely locate the defect.  
         [0007]     A common way of detecting longitudinal defects magnetically is the “rotating pole” method, where the magnetic field is applied from the outside by rotating electromagnets and where detectors positioned in-between the poles scan the outside surface of the pipe. Tubing wall thickness has been measured by measuring the radiation from an external rotating radioactive source of gamma radiation transmitted through the wall of a tubing section to a detector positioned inside the pipe. Other ways of measuring wall thickness with gamma radiation, which are backscatter, double-wall through-transmission and chord, have both the radiation detector and the source located on the outside of the pipe.  
         [0008]     One technique for inspecting tubular elements which is adaptable to relative movement, at variable velocities, is a technique involving the use of a saturating longitudinal magnetic field and the subsequent measurement of the time integral of the electrical signal caused by the magnetic field applied to the ferromagnetic tubular member to determine the average wall thickness. Testing using this technique has been conducted for surface pipe installations in which the magnetic field and the flux detecting elements are moved relative to a continuous pipe array.  
         [0009]     Electromagnetic inspection systems are known which have been used to locate flaws and defects in tubular goods. Typically, the electromagnetic inspection system uses sensors to detect magnetic flux leakage which occurs when a discontinuity is present in the tubular wall section. Conventionally, the sensors rotate around the tubular in a fixed rotating housing as the tubular is conveyed linearly through the rotating housing by conventional conveying means. The rotating sensors maintain contact with the surface of the tubular during inspection activities. The magnetic field is introduced into the tubular by electromagnets contained in the rotating detector housing or by a residual magnetic field magnetizing means prior to the tubular entering the rotating detector assembly. The use of electromagnets attached within the rotating detection housing requires the use of slip rings and brushes to convey the electrical power to the electromagnets that are located 180 degrees apart in the rotating housing. The electromagnets are positioned 90 degrees from each of the two sensors which are themselves positioned opposite to each other in the rotating detection housings. The electromagnets are mounted within the rotating assembly at a fixed distance from the tubular outside diameter surface. Metal shim plates are attached to the electromagnets in order to adjust the electromagnet&#39;s pole face to within close proximity to the tubular outside diameter surface. These metal shim plates will vary in thickness in order that the shim plate pole face will be within close proximity to the tubular outside surface in order that a sufficient magnetic field for inspection detector sensitivity is introduced into the tubular wall thickness section. The close proximity distance of the electromagnetic shimmed pole face is not sufficient to allow passage of a tubular with large outside diameter upset connections. This is important since tubulars with large upset connections are used extensively in oil and gas drilling operations worldwide. The electromagnets are positioned in such a manner that will cause the resultant magnetic fields generated by each electromagnet to add to the total resultant magnetic field. A total resultant magnetic field is enhanced by aligning the center axis of each of the electromagnetic coils. The total resultant field is further optimized by positioning one electromagnetic coil to produce a north/south magnetic field and positioning the other magnetic coil to produce a south/north magnetic field. The electromagnetic coils do not contact the tubular surface, but are maintained in close proximity to the tubular surface in order to maintain an optimum magnetic field in the tubular wall sections.  
         [0010]     The use of the residual circumferential magnetic field applied to each tubular prior to entering the rotating detector assembly eliminates the need for electromagnets in the rotating housing. The residual circumferential magnetic field is induced into the tubular wall by inserting a magnetizing rod through the full length of the internal diameter of the tubular. A cable is attached to each end of the magnetizing rod which is protruding from each end of the tubular. The cables are attached to a capacitor discharge system or a battery pack discharge unit. Such capacitor discharge systems or battery pack discharge units are commercially available. The capacitor discharge system or battery pack discharge unit is suitably activated. The residual circumferential residual magnetic field that is generated 360 degrees into the tubular wall is utilized for detection of longitudinally-oriented flaws or defects in the test object.  
         [0011]     When utilizing either the electromagnets or the residual circumferential magnetic method described above, slip rings are necessary for conveying the signal from the sensors contained within the rotating frame for interpretation by inspection personnel. The use of either the electromagnets or the residual circumferential magnetic methods described hereinabove also requires that the linear tubular conveyer requires that both speed of the conveyor and rotating velocity (rpm) be controlled and synchronized in order that the resultant helical path of the sensors provides 100% or more of inspection coverage. Also, the use of the electromagnets or the residual method requires the rotating assembly to be balanced by distributing the detectors and/or electromagnets opposite to each other.  
         [0012]      FIG. 1  illustrates such a prior art system of electromagnetic inspection. As can be seen in  FIG. 1 , the rotating inspection housing  10  contains non-adjustable electromagnets  12  and  13 . The electromagnets  12  and  13  are rotated about a linearly conveyed non-rotating tubular  11 . The electromagnets  12  and  13  are fitted with detachable shim plates  15  and  17 . Shim plates  15  and  17  are attached to the pole face of the electromagnets  12  and  13 , respectively, in order that the pole face is within close proximity to the outer surface of the tubular  11 . The electromagnets  12  and  13  are electrically activated by way of slip rings and slip ring brushes  18  as the inspection housing  10  is rotated around the linearly conveyed non-rotating tubular  11 . It can be seen that the inspection flux leakage detectors  14  and  16 , which are contained in the rotating inspection housing  10 , are mounted 90° relative to the electromagnets  12  and  13  so as to detect electromagnetic flux leakage  19  when a longitudinally-oriented flaw or defect  21  is present within the tubular  11 . The electromagnetic flux lines  20  remain with the wall  24  of the tubular  11  unless a longitudinally-oriented flaw  21  is present. The rotating detectors  14  and  16  remain in contact with the outside surface of the tubular  11  during the inspection process. The detection signal generated by a flaw or defect  21  is conveyed from the inspection detectors  14  and  16  via slip ring and slip ring brushes  18  to an inspection processor in a manner known in the art.  
         [0013]     It can be seen in  FIG. 1  that a small air gap  22  is maintained between the electromagnets  12  and  13  and the outside surface of the tubular  11  in order to allow the electromagnets to not grab the tubular  11  or slow the rotating housing or tubular conveyance. The air gap  22  is changed for different outside diameters of the tubular  11  by use of the detachable shim pole plates  15  and  17 . The shim pole plates  15  and  17  are manually changed when the outside diameters of the tubular  11  are changed. The electromagnets  12  and  13  and the shim pole plates  15  and  17 , respectively, do not open and close. As a result, when the tubular  11  has large upset connections, the tubular  11  cannot be properly inspected.  
         [0014]     In the past, a variety of patents have issued with respect to the electromagnetic inspection of tubulars and other objects. For example, U.S. Pat. No. 4,096,437, issued on Jun. 20, 1978 to Kitzinger et al., describes a magnetic testing device for detecting loss of metallic area in internal and external defects in elongated objects. The testing device includes a permanent magnet assembly having poles adapted to be spaced apart in the longitudinal direction of the elongated object for inducing a longitudinal magnetic flux in a section of the object between the poles of the magnet assembly. This flux is strong enough to saturate each section of the object. A tubular pole piece is substantially centered on the elongated object adjacent each pole of the permanent magnet assembly for directing the magnetic flux radially into the object at one pole and out of the object at the other pole. Hall effect devices are spaced around at least one pole piece in the path of the magnetic flux for sensing the radial flux entering into the elongated object. Means are provided for sensing the variations of such magnetic flux as an indication of loss of metallic area in the object.  
         [0015]     U.S. Pat. No. 4,101,832, issued on Jul. 18, 1978 to Baker et al., provides a multiprobe eddy current flaw detection device having a suitable means for raising and lowering the individual probes. A plurality of pickup arms are mounted in spaced relation with respect to each other around a work path and a plurality of sensing coils are carried by each of the pickup arms. The pickup arms are each mounted on a support member to pivot on an axis transverse to the direction of the work path so that the sensing coils may be moved into proximity and around the circumference of a workpiece as the workpiece travels along the work path.  
         [0016]     U.S. Pat. No. 4,379,261, issued on Apr. 5, 1983 to K. M. Lakin, shows a rotating magnetic field device for detecting cracks in metal. This device has input signal coils on cores radially arranged around a center and having outer ends of the cores which rest against a surface of a metal assembly to be tested for defects. The input coils are energized by an AC signal of different phase for each respective coil so that a rotating magnetic field is produced in the assembly being tested. An output sensor coil is mounted at the center of the tester immediately adjacent to such test surface for coupling out a signal induced from the rotating field.  
         [0017]     U.S. Pat. No. 4,492,115, issued on Jan. 8, 1985 to Kahil et al., describes a method and apparatus for measuring defects in ferromagnetic tubing. A saturating magnetic field and a fluctuating magnetic field are applied to the tubing. The magnitude of the induced fields and the changes are measured to quantify defects in the tubing. U.S. Pat. No. 4,636,727, issued on Jan. 13, 1987, is another patent by Kahil et al., which describes a similar process for detecting and locating the defects in tubular sections. U.S. Pat. No. 4,710,712, issued on Dec. 1, 1987 to Bradfield et al., also describes a similar system for the use of a saturating magnetic field for the detection of defects in tubing. U.S. Pat. No. 4,792,756, issued on Dec. 20, 1988 to Lam et al., also a slight variation on the previous patents issued to Kahil et al. and to Bradfield et al. U.S. Pat. No. 5,157,977, issued on Oct. 27, 1992 to R. C. Grubbs, teaches an apparatus for feeding, indexing, testing, and storing tubular goods. This machine uses the eddy current test method to test the outer surface, the inner surface, and internal and external threads of the tubular. The pipe is spun during the examination so that the sensors of the inner and outer surfaces, when driven, trace a helical pattern on the pipe.  
         [0018]     U.S. Pat. No. 5,377,553, issued on Jan. 3, 1995 to W. H. Knepper, Jr., describes a transducer support device that is employed with magnet flux leak detector so as to render the detector sufficiently compact and lightweight to facilitate the use thereof at the wellhead of an oil well so as to avoid lay-down horizontal inspection at a location away from the wellhead.  
         [0019]     U.S. Pat. No. 5,442,278, issued on Aug. 15, 1995 to Kammann et al., teaches a method and apparatus for detecting magnetic discontinuities by inducing a magnetic field into a magnetizable sample. The apparatus includes an electric motor, a transmission, driven transport wheels, and non-driven transport wheels. The apparatus includes a magnetic for inducing a magnetic field in the sample. A sensor unit detects magnetic stray flux from the magnetic field induced in the sample and converts the detected magnetic stray flux into a signal for processing by a signal processor.  
         [0020]     U.S. Pat. No. 5,600,069, issued on Feb. 4, 1997 to Girndt et al., provides an ultrasonic testing apparatus and method for multiple diameter oilfield tubulars. The apparatus includes four ultrasonic arrays each containing a plurality of individual watertight ultrasonic transducers. Axially adjustable ultrasonic arrays include axially spaced sockets for controlling an axial movement thereof to discrete positions associated with each selected range of diameters to be tested. During scanning, the tubular is moved axially and rotationally with respect to an ultrasonic testing apparatus to provide a helical scan pattern along the length of the tubular.  
         [0021]     U.S. Pat. No. 5,793,205, issued on Aug. 11, 1998 to Griffith et al., describes a coil and guide system for eddy current examination of pipe. This apparatus includes an eddy current coil adapted to removably circumferentially surround the pipe. The coil includes a cable having a plurality of conductors adapted to form a continuous conductor coil when the cable is circumferentially wrapped around the pipe.  
         [0022]     U.S. Pat. No. 6,249,119, issued on Jun. 19, 2001 to Curtis et al., teaches a rotating electromagnetic field defect detection system for tubular goods. This system includes an encircling coil for providing a saturating DC magnetic field the to tubular. An encircling drive coil applies a low level AC field using three-phase AC. Encircling pick up coils within the AC drive coils detect uniform, time-varying magnetic fields in order to reveal defects within the tubular passing through the system.  
         [0023]     U.S. Pat. No. 6,271,670, issued on Aug. 7, 2001 to T. W. H. Caffey, describes a method and apparatus for detecting external cracks from within a metal tube. A continuous electromagnetic wave from a transverse magnetic-dipole source with a coaxial electric-dipole receiver is used for the detection of the external side wall cracks and other anomalies in boiler tubes.  
         [0024]     It is an object of the present invention to provide an apparatus and method that allows for the locating of longitudinally-oriented discontinuities or flaws in a test object.  
         [0025]     It is another object of the present invention to provide a non-rotating inspection assembly for the inspection of tubulars.  
         [0026]     It is another object of the present invention to provide a method and apparatus for electromagnetic flaw detection which avoids the use of slip rings and brushes.  
         [0027]     It is a further object of the present invention to provide an electromagnetic flaw detection apparatus which allows tubulars with the large upsets to be inspected.  
         [0028]     It is a further object of the present invention to provide an electromagnetic flaw detection apparatus and method that is suitable for accommodating tubulars of different diameters.  
         [0029]     It is a further object of the present invention to provide an electromagnetic flaw detection apparatus that completely covers the length of tubular without gaps in the inspection.  
         [0030]     It is a still another object of the present invention to provide an electromagnetic flaw detection apparatus which is easy to use and relatively inexpensive.  
         [0031]     These and other objects and advantages of the present invention will become apparent from the reading of the attached specification and appended claims.  
       BRIEF SUMMARY OF THE INVENTION  
       [0032]     The present invention is an electromagnetic flaw detection apparatus for inspection of a tubular. The apparatus comprises a frame having an interior suitable for receiving a diameter of the tubular therein. This frame is non-rotatable. A first electromagnetic field generating means is connected to the frame. A second electromagnetic field generating means is also connected to the frame and arranged to be positioned on an opposite side of a tubular passing through the frame from the first electromagnetic field generating means. The first and second electromagnetic field generating means serve to generate a circumferentially-oriented magnetic flux field relative to the tubular passing therebetween. A first sensor is positioned with respect to the frame so as to be movable between a first position away from the tubular and a second position in proximity to the tubular. A second sensor is positioned with respect to the frame so as to be movable between a first position away from the tubular and a second position in proximity to the tubular. Each of the first and second sensors are suitable for detecting flux leakage from the magnetic flux field generated by the first and second electromagnetic field generating means. A tubular conveyance means is cooperative with the frame for moving the tubular in a helix path along a longitudinal axis of the tubular toward and through the frame.  
         [0033]     In the present invention, the first and second sensors are arranged so as to be on opposite sides of the tubular passing through the frame. Each of the first and second sensors are offset by approximately 90° from the first and second electromagnetic field generating means.  
         [0034]     The first electromagnetic field generating means includes a first electromagnet affixed to the frame and extending inwardly into the interior of the frame. The second electromagnetic field generating means includes a second electromagnet affixed to the frame and extending inwardly into the interior of the frame. A first fluid-actuated cylinder is connected to the frame and to the first electromagnet so as to move the first electromagnet between a position away from the tubular and a second position in proximity to the tubular. A second fluid-actuated cylinder is also connected to the frame and to the second electromagnet so as to move the second electromagnet between a first position away from the tubular and a second position in proximity to the tubular. In particular, in one embodiment of the present invention, a first guide rod is affixed to the frame and extends thereacross. A first guide arm is slidably connected to this first guide rod and fixedly connected to the first electromagnet. A second guide arm is slidably connected to the first guide rod and is also fixedly connected to the second electromagnet. A second guide rod is affixed to the frame and extends thereacross in generally parallel relationship to the first guide rod. A third guide arm is slidable connected to the second guide rod and is fixedly connected to the first electromagnet. A fourth guide arm is slidably connected to the second guide rod and is fixedly connected to the second electromagnet.  
         [0035]     In the present invention, a first fluid-activated cylinder is connected to one side of the frame and to the first sensor so as to selectively move the first sensor between the first and second positions. A second fluid-activated cylinder is connected to an opposite side of the frame and to the second sensor so as to selectively move the second sensor between the first and second positions.  
         [0036]     A translating means is connected to the frame so as to non-rotatably translate the frame with respect to the tubular passing therethrough so as to allow the sensors and electromagnets to be utilized in association with different diameters of pipe. The tubular conveyance means provides the tubular with a helix path width. This helix path width is no greater than 90° of the length of the sensor.  
         [0037]     The present invention is also a method of electromagnetically inspecting longitudinally-oriented discontinuities in a tubular that comprises the steps of: (1) forming a frame having an electromagnet affixed thereto and a sensor translatably mounted thereto; (2) passing the tubular along a helix path along a longitudinal axis of the tubular and into an interior of the frame; (3) moving the sensor into close proximity with an exterior surface of the tubular; (4) applying a circumferentially-oriented magnetic flux field by the electromagnetic onto the tubular as the tubular passes adjacent to the electromagnet; and (5) sensing flux leakage from the tubular from the magnetic flux field applied by the electromagnet.  
         [0038]     In this method of the present invention, the step of forming includes forming a frame so as to have a first electromagnet and a second electromagnet extending inwardly from opposite sides of the frame and forming the frame so as to have a first sensor and second sensor extending inwardly from opposite sides of the frame. The first and second sensors are positioned approximately 90° from the first and second electromagnets. In the method of the present invention, electromagnets are moved into proximity with an exterior surface of the tubular as the tubular passes into the frame. The frame can be non           
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0039]      FIG. 1  is an end view of an electromagnetic flaw detection apparatus in accordance with the prior art.  
         [0040]      FIG. 2  is an end view of the preferred embodiment of the electromagnetic flaw detection apparatus of the present invention.  
         [0041]      FIG. 3  is a side elevational view of the electromagnetic flaw detection of  FIG. 2 .  
         [0042]      FIG. 4  is a plan view of the electromagnetic flaw detection apparatus of  FIG. 2 .  
         [0043]      FIG. 5  is an end view showing an alternative view of the electromagnetic flaw detection apparatus of the present invention  
         [0044]      FIG. 6  is an end view of the alternative embodiment of  FIG. 5  showing, in particular, the use of the alternative embodiment in association with a tubular having an upset formed thereon.  
         [0045]      FIG. 7  is a plan view of the alternative embodiment of  FIG. 5  illustrating the use of the present invention in association with an upset of a tubular.  
         [0046]      FIG. 8  is a plan view of the alternative embodiment of the present invention, as illustrated in  FIG. 6 , showing the use of the present invention in association with an upset of a tubular. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0047]     Referring to  FIG. 2 , there is shown the electromagnetic flaw detection apparatus  29  in accordance with the preferred embodiment of the present invention. The electromagnetic flaw detection apparatus  29  includes a non-rotating inspection frame  31 . A first electromagnet  37  is affixed to one side of the frame  31  and extends inwardly therefrom. A second electromagnet  38  extends inwardly from an opposite side of the frame  31 . A first fluid-activated cylinder  36   a  is affixed to the frame  31  and extends inwardly therefrom. A second fluid-activated cylinder  36   b  is affixed to an opposite side of the frame  31  from fluid-activated cylinder  36   a  and also extends inwardly therefrom. The tubular  30  is illustrated as extending between the electromagnets  37  and  38  and the fluid-activated cylinders  36   a  and  36   b . It can be seen that the fluid-activated cylinder  36   a  has a detector  34  that is placed into close proximity to the outer wall of the tubular  30 . The fluid-activated cylinder  36   b  has a detector  35  that is placed into proximity with an outer surface of the tubular  30  on an opposite side of the tubular  30  from the detector  34 . As will be described hereinafter, the frame  31  has a fluid-activated cylinder  36   a  that is suitable for moving the detector  34  between a first position away from the tubular  30  and a second position in proximity to the tubular  30 . Similarly, the frame  31  has a cylinder  36   b  that is suitable for moving the detector  35  from a position away from the tubular  30  to a position in proximity to the outer surface of the tubular  30 .  
         [0048]     In  FIG. 2 , it can be seen that the electromagnets  37  and  38  are wired directly to electrical power. The electromagnets  37  and  38  include pole face shims  39  and  40 , respectively. The pole face shims  39  and  40  are attached to the electromagnets  38  and  37  to within close proximity of the outer diameter of the tubular  30  which requires inspection. The inspection detectors  34  and  35  are placed 90° from the electromagnets  37  and  38 . The electromagnetic field flux  42  crosses the air gap  43  from the electromagnet  37 , enters the tubular  30 , and exits across air gap  44  into the electromagnet  38 . Cylinders  43  and  44  can raise and lower the frame  31  in order to adjust the frame  31  to accommodate different outside diameters of various tubulars.  
         [0049]     In  FIG. 3 , it can be seen that the tubular  30  is illustrated as being moved through the frame  31 . It can be seen that the detectors  34  and  35  are positioned by the respective cylinder  36   a  and  36   b  into close proximity with the outer diameter  30   a  of the tubular  30 . The electromagnet  37  is illustrated as located between the detectors  34  and  35 . For the purposes of illustration, the electromagnet  37  is actually 90° from each of the detectors  34  and  35  relative to the longitudinal axis of the tubular  30 .  
         [0050]     The present invention utilizes a conveyance method of the prior art to cause the tubular  30  to move through a non-rotating inspection assembly. The tubular conveyer causes the tubular  30  to helix in the forward or reverse direction along the longitudinal axis of the tubular  30 . Each of the individual rollers of the conveyer is set at the same inclination angle relative to the longitudinal axis of the tubular to allow for a helix path  32  throughout the entire length of the conveyer. By changing the inclination of the conveyance rollers the helix  32  can be easily reset for different sizes of the outer diameter  30   a . The individual roller, can be individually adjusted by using a marked indexing alignment method or by an adjustment rod connected in common to all of the individual rollers contained in the conveyance device. Once all of the rollers are set and locked into position, the helix path  32  can be verified manually by using a mounted paint stick tracing device which lowers the paint stick into contact with the helixing tubular  30 . The distance between the traced paint stick marks on the outer surface  30   a  of the tubular  30  is measured along and parallel to the longitudinal axis of the tubular  30  and can be verified to assure a proper helix path required for 100% plus inspection coverage. In  FIG. 3 , it can be seen that the helix path width  33  is maintained at no greater than 90° of the length of the detectors  34  and  35 . This achieves 100% plus inspection coverage for longitudinally-oriented flaws or defects, such as defect  41 . As was described hereinbefore, the inspection detectors  34  and  35  are opened and closed around outer surface  30   a  of the tubular  30  by utilizing air or hydraulic cylinders  36   a  and  36   b.    
         [0051]      FIG. 4  illustrates how the electromagnets  37  and  38  are placed into close proximity to the outer surface  30   a  of the tubular  30 . The detector  34  is illustrated as positioned between the electromagnets  37  and  38 . Pole face shims  39  and  40  are illustrated in  FIG. 4  as being placed in close proximity to the outer surface  30   a  of tubular  30 .  
         [0052]     As can be seen in  FIG. 4 , there are cylinders  43 ,  44 ,  45  and  46  that are connected to the various corners of the frame  31 . These cylinders  43 ,  44 ,  45  and  46  raise and lower the inspection frame  31  in order to adjust the frame  31  to accommodate different tubular outside diameters.  
         [0053]     Referring to  FIG. 5 , there is shown the electromagnetic flaw detection apparatus  49  in accordance with an alternative embodiment of the present invention. The apparatus  49  includes a frame  50  having a configuration somewhat similar to that of the previous embodiment. In  FIG. 5 , it can be seen that a tubular  52  has a large outside diameter upset connection  51  located at an end thereof. The tubular  52  is helixed by the conveyer described hereinabove and through the non-rotating frame  50 . The frame  50  can be raised or lowered by hydraulic cylinders  69  and  70 . Additional hydraulic cylinders, not shown, are provided at the opposite end of the frame  50  from hydraulic cylinders  69  and  70 . The hydraulic cylinders  69  and  70  are utilized so as to raise and lower the frame  50  in order that the centerline of the electromagnets  57  and  58  are aligned with the centerline of the upset  51  of the tubular  52 . It can be seen in  FIG. 5  that the electromagnets  57  and  58  are extended and/or retracted by fluid-actuated cylinders  59  and  60 , respectively. The movement of the electromagnets  57  and  58  through the use of the fluid-actuated cylinders  59  and  60 , allows for the passage of the large diameter upset  51  of tubular  52 . The electromagnets  57  and  58  are mounted within the frame  50  on guide rods  62  and  63 . The electromagnet  58  has guide arm  64  affixed thereto and slidably mounted on the guide rod  62 . The electromagnet  58  also has guide arm  65  extending in an opposite direction from guide  64  and slidably connected to the guide  63 . The guide rod  62  is in generally parallel relationship to the guide rod  63 . The electromagnet  57  also includes guide arms  66  and  67  which extend outwardly therefrom in opposite directions. Guide arms  66  and  67  are also slidably mounted onto the guide rods  62  and  63 . The use of the guide arms  64 ,  65 ,  66  and  67  stabilizes the electromagnets through cooperation with the guide rods  62  and  63 . Guide rods  62  and  63  extend across the frame  50  and are fixedly mounted thereto.  
         [0054]     In  FIG. 5 , it can further be seen that the fluid-actuated cylinder  60  is mounted onto a plate  79  extending outwardly on one side of the frame  50 . The fluid-actuated cylinder  59  is mounted on a plate  80  that extends fixedly outwardly from the frame  50 . Plates  79  and  80  provide stability for the fluid-actuated cylinders  60  and  59 , respectively. The fluid-actuated cylinders  59  and  60  can be either air or hydraulic cylinders.  
         [0055]     In  FIG. 5 , a cylinder  53  and a cylinder  54  are mounted on opposite sides of the tubular  52 . The cylinder  53  is mounted to the frame  50  through the use of a mounting plate  77 . Similarly, the cylinder  54  is connected to the plate  50  through the use of a mounting plate  78 . The cylinder  53  has detector  55  positioned so as to be in proximity to the upset  51  of the tubular  52 . Similarly, the cylinder  54  includes the detector  56  and is also mounted in proximity to an opposite side of the upset  51  of tubular  52 . The fluid-actuated cylinder  53  allows the detector  55  to move between a position in proximity to the upset  51  and a position away from the upset  51 . Similarly, the fluid-actuated cylinder  54  allows the detector  56  to move between a position in proximity to the upset  51  and a position away from the upset  51 . The movement of the detectors  55  and  56 , along with the electromagnets  57  and  58 , allows the large diameter upset  51  to easily pass through the frame.  
         [0056]     In  FIG. 6 , it can be seen that once the large upset  51  has moved past the electromagnets  57  and  58 , the fluid-actuated cylinders  59  and  60  activate to close the electromagnets  57  and  58  to within close proximity to the smaller diameter of the tubular  52 . In  FIG. 6 , once the large upset  51  has moved past the inspection detectors  55  and  56 , then cylinders  53  and  54  activate to close the inspection detectors  55  and  56  onto the smaller diameter portion of the tubular  52 .  
         [0057]     Referring to  FIG. 6 , it can be seen that the tubular upset  51  and the tubular  52  helix through the frame  50  with a helix path  1 . The electromagnets  57  and  58  are illustrated as closed as are the inspection detectors  55  and  56 . The closed electromagnets  57  and  58  are activated to induce an electromagnetic flux field  61  from the electromagnets  58  across the air gap  69  and into the wall  75  of the tubular  52  and then across the air gap  70  and into the electromagnet  57 . The closed inspection detectors  55  and  56 , which are in contact with the outer surface of the tubular  52 , will detect flux leakage from longitudinal flaws or defects present in the tubular  52 .  
         [0058]     Referring to  FIG. 7 , the large upset  51  will helix forward into the inspection frame  50 . Cylinders  59  and  60  have retracted and opened the respective electromagnets  58  and  57  by way of the guide arms  65 ,  66 ,  75  and  76  which are attached to guide rods  62  and  78 . Also, in  FIG. 7 , it can be seen that the cylinders  53  and  54  have retracted and opened the inspection detectors  55  and  56  in order to allow the large upset  51  to pass forward into the inspection frame  50 . The various mounting plates  77 ,  78 ,  79  and  80  can contain proper bolt slots which are used to adjust respective cylinders in order to accommodate various diameters of the tubular  52 .  
         [0059]     In  FIG. 8 , it can be seen that once the large upset  51  has helixed past the electromagnets  57  and  58 , the fluid-actuated cylinders  59  and  60  activate to close the electromagnets  57  and  58  to within close proximity to the small diameter of tubular  52 . In  FIG. 8 , once the large upset has moved past the inspection detectors  55  and  56 , then the cylinders  53  ad  54  activate to close the inspection detectors  55  and  56  onto the smaller diameter portion of the tubular  52 .  
         [0060]     The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction can be made within the scope of the appended claims without departing from the true spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.